data logging & control

lux volt milliRoger Frost

IT in Science Publishing www.rogerfrost.com

ISBN 0-9520277-1-XEAN 9780952025719

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Data logging & controlThe IT in Science book of

A4 front cover 1 of 2 PANTONE 341 and 369 cvc

The IT in Science book of

Data logging andcontrol

Roger Frost

A compendium of ideas for using sensors in science teaching with pupilsaged from 11 to 18

The companion guide to The IT in Secondary Science Bookand Data logging in Practice

Titles in this series:

The IT in Secondary Science BookISBN 0-9520257-2-8

The IT in Science Book of data logging and controlISBN 0-9520257-1-XIT in Primary ScienceISBN 0-9520257-3-6

Data logging in PracticeISBN 0-9520257-4-4

Software for science teachingISBN 0-9520257-5-2

IT in Science 2002 Russet House Cambridge CB2 6RT Tel: 01763 209109ISBN 0-9520257-1-X

The IT in Science book of Data logging and Control

Section

1Introduction

4

About this bookThis book aims to show how useful sensors can be in for teaching science to pupilsaged between 11 and 18. You can, at last, do virtually all of the experiments in thisbook on any brand of school computer.The ideas here come from many science teachers and especially those in the LondonBorough of Bromley who through their MAPOSE project, first showed what could bedone. Extra thanks are due to Keith Hemsley, Rosie Kentish for editorial help, DavidPalmer of LogIT and Alan North and Alison Bilsborough for technical advice andloans of equipment, Craig Ecclestone of Data Harvest, US for encouragement.While this book is copyright, you are welcome to copy and amend sheets for use inclass but of course, not sell copies. If you copy pages for in-servicetraining, please mention their source. And incidentally, If you'd would like trainingcontact me via the publishers.Roger Frost. Email: press(at)rogerfrost.comResources and information for science are available on the Internet at:www.rogerfrost.com

About the authorRoger Frost was an analytical biochemist for ten years before becoming a teacherof science and computing. In 1988 he became a science and IT advisory teacherfor ILECC, the London computer centre and later for North London ScienceCentre. He now works as a freelance writer, and runs training days for science teachersusing IT. His work includes titles overleaf and also:Learning Highways - the potential of the Internet (NCET) 1-85379-401-5Enhancing Science with IT (NCET) 1994 Co-author ISBN 1 85379270 5The IT in Primary Science Book (IT in Science), 1993 ISBN 0-9520257-0-1Information Technology (Nelson), 1993 Co-author ISBN 0-17-438572-2The IT in Science Blue book, (IT in Science), 1992 Out of printThe IT in Science Buff book, (IT in Science), 1991 Out of print

About this publicationThe IT in Science book of Data logging and control. ISBN 0-9520257-1-XWritten and produced by Roger Frost. Printing and finishing by The Printing Centre,London W1. First published January 1993. Reprinted February 1993, December 1993,April 1995 (update), November 1995, January 1997, September 1997, October 1998,June 1999, September 2002, September 2003, December 2004IT in Science & Roger Frost, Tel: 0845 430 0176 / 01763 209109Russet House, Foxton, Cambridge, CB2 6RT press(at)rogerfrost.comBritish Library Cataloguing in Publication Data: a catalogue record for this book isavailable from the British library.UK: The Association for Science Education, College Lane, Hatfield, Herts. AL109AA. Tel: 01707 267411. Fax: 01707 266532 Web: www.ase.org.ukTTS, Nunn Brook Rd, Huthwaite, Sutton-in-Ashfield, Notts NG17 2HUTelephone 01623 447800 Web: www.tts-group.co.ukGriffin & George Ltd www.fisher.co.ukData Harvest www.data-harvest.co.ukAustralia: Southern Biological PO Box 57Nunawading, Vic. 3131. Tel: 03 9877 4597 Fax: 03 9894 2309www.southernbiological.comAustralia: Tain Electronics, 10 Rowern Court, Box Hill North, Vic 3129Tel: 03 9898 7366 Web: www.tain.com.auNew Zealand: Education Advisory Services, Private Bag 92601, Symonds St,AucklandUSA: Fisher Education Tel: 1 800 955 1177 Internet: www.fisheredu.com/USA: Data Harvest Educational 1-905 828 6166 www.dataharvest.com

Canada: www.dataharvest.comPlease address bulk enquiries to the publisher.


Section

1Introduction

5

About data logging and control

Scientists are forever looking for better ways to studythe world. Information technology comprises many

tools, including measuring tools, which help them to dothis.Spreadsheets, CD-ROM databases, database programs andword processors help in various ways. Sensors and controltechnology help in unique ways. They provide not justbetter methods of measurement but also the means to helpstudents understand and explore science. In particular, wecan

Monitor unique changes and even very fast events,for example the speed of a falling weight or thedischarge of a capacitor.

Measure with more precision and therefore have agreater certainty about our results.

See our results immediately gaining a better feel forchanges and quantities as well as using this toimprove our experimental technique.

Analyse our data and test our ideas more readily. Explain the workings of our automated world

through project work with control technology.

Over the years the software and the hardware for datalogging and control have improved to make all the above apractical reality in the classroom.This book is a not-too-technical, technical guide toactivities with sensors in the classroom. It shows what canbe done and provides many starting points to introducepupils to tools which they can use to understand andinvestigate science better than they ever have before.

See:

A curriculum Pages 8-9Sensing glossary Page 10


Section

1Introduction

6

Contents

1 Introduction .......................................... 5

Progression with IT ................................. 9Assessment ............................................... 8Sensing glossary ..................................... 10

2 Ideas ..................................................... 11

Biology ................................................... 12Chemistry .............................................. 21Physics ................................................... 23

3 Data logging for age 10-13 ................. 33

Keeping baby warm ............................... 34How can we keep warm? ........................ 36Making your hot drink cool ................... 38Can you trust your ears? ........................ 40What can sound travel through? ............ 42The best way to stop sounds ................... 44Which light is the brightest? .................. 46What should a cyclist wear? ................... 48Stopping light from a window ................ 50

4 Exploring science with sensors ............ 52

5 Control ................................................. 62

Control glossary ..................................... 63Ideas for Control ................................... 65Automatic porch light ............................ 66Bath water tester .................................... 67Sound controlled alarm ......................... 68Cooling Fan ........................................... 69Keeping a kettle on the boil ................... 70Thermostatic Control ............................. 71

6 Sensing for age 14+ ............................. 73

Pulse measurement ................................ 74Arterial pulse / Sphygmograph .............. 76Breathing movements ............................ 77Enzymes: starch and amylase ................. 79Enzymes: pepsin and protein ................. 80Photosynthesis ....................................... 81Respiration ............................................ 83Energy from germinating seeds .............. 84Energy in food ....................................... 85Aerobic & anaerobic respiration ............. 86Fermentation ......................................... 87Fermentation - long experiment ............ 88Osmosis .................................................. 89Plant growth - long experiment ............. 90Oxygen solubility ................................... 96Radioactive Decay .................................. 92Penetration by radiation ........................ 93Magnetic fields ....................................... 94Seismometer ........................................... 95Battery life ............................................. 96Heating effect of electric current ............ 97Thermistor characteristics ..................... 99Current-Voltage relationships ...............101Capacitor charge and discharge ............103Pressure & temperature ........................104Heat conduction ...................................105Heat insulation .....................................106Cooling curve ........................................107Extension of a spring ............................108Oscillator motion ..................................109Absorption of thermal radiation ............110Heats of reaction ...................................111Exothermic reactions ............................112Rates: Thiosulphate and acid ................113Rates: marble and acid ..........................114Acid-base titration .................................115Thermometric titration .........................117Burning a candle ..................................118Weather station .....................................119

7 Sensors and software .........................120

Sensors ..................................................120Software for data logging ......................126

Index


Section

1Introduction

7

Quick overview

This book is a catalogue of ideas for using computer-linkedsensors to enhance the teaching of science.

1 Introducing data logging and controlThis section describes how sensors help teaching and how pupilskills might develop as students move through the educationsystem. The glossary here describes the data logging technologyyou might meet.

Page 5

2 Ideas for data logging and controlThis is a compilation of ideas organised by subject.

Page 11

3 Introducing data loggingExample worksheets for starting out to use sensors.

Page 33

4 Exploring science with sensorsSensors allow us to investigate science and this is anotherapproach you can try.

Page 52

5 ControlIdeas and examples for control projects or demonstrations.

2

6 Sensing for age 14 +All-purpose experiment guides using sensors

Page 73

7 Sensors and software

About the available sensors and software.Page 120

Index

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Section

1Introduction

8

A curriculum

The following table is a guide to the way pupils might progress withtheir use of sensors and control technology.

Progression in measuring andcontrolling things

What the pupils do in science (ortechnology)

Recognise that everyday devicesrespond to signals and commandsand they can make them respondin different ways.

Talk about how to use a videorecorder.

1

Control devices purposefully anddescribe the effects of their actions.

Technology: introduce robots. 2

Understand how to controlequipment to achieve specificoutcomes by giving a series ofinstructions.

Technology: control a robot. 3

Use IT to control events in apredetermined manner, to collectphysical data and display it.

Technology: control a robot andmake it perform a set routine. Usesensors to make measurementsand display readings.

4

Create sets of instructions tocontrol events, and becomesensitive to the need for precisionin framing and sequencinginstructions.

Technology: control a robot andmake it perform a set routine.

5

Develop, trial and refine sets ofinstructions to control events,demonstrating an awareness of thenotions of efficiency and economyin framing these instructions.Understand how IT devices can beused to monitor and measureexternal events, using sensors.

Technology: control a robot, makeit perform a set routine and not becontent with just getting it to work.Use sensors to makemeasurements, for example, usedigital sensors to measure theirreaction time.

6

Use IT equipment and software tomeasure and record physicalvariables.

Use sensors to makemeasurements in experiments. Usea data logger to record the roomtemperature and light level over aweekend. Display readings as timegraphs.

7

Select the appropriate IT facilitiesfor specific tasks, taking intoaccount ease of use and suitabilityfor purpose. Design successfulmeans of capturing and preparinginformation for computerprocessing. When assemblingdevices that respond to data fromsensors, they describe howfeedback might improve theperformance of the system.

Use sensors to makemeasurements in experiments.Select appropriate sensors andrecording parameters. Use the datain the data logging program orexport it to a spreadsheet or wordprocessor. Develop a controlsystem to run a biofermenter, anaquarium or fire alarm. Discuss anddocument the work to a highstandard.

8


Section

1Introduction

9

Learning to use sensors

Progression is no less important in using computers andsensors than any other part of the curriculum. How then

might pupil's skills develop as they move through school?This list is one answer.

Age 5-7

Use sensors to show whose hands are hottest. Show, usinggraphical or bar displays, which things are hot or which

sound is loudest or which place is darkest? For a primer oncontrol, they might learn to use video recorders,programmable toys or robots.

Age 8-11

Use temperature sensors instead of thermometers toinvestigate the cooling of a drink. Use other sensors as

opportunities arise. Consider the advantages of sensors overhuman sensors and suggest some uses for them around thehome. Use control technology to power models (just on/off tostart with) and develop this further (move left/right, fast/slow).Do a control project that combines the use of sensors withcontrol.

Age 11-13

Develop the use of sensors - starting with some initialdemonstrations - moving onto investigations. Introduce

different sensors, show what they measure and how they areused at home. Pupils might also learn to use a data logger tosay, compare indoor and outdoor temperatures over the day.Use digital sensors for measuring their reaction time orthings sliding down a slope. Build a control system such as anair conditioning system or a baby incubator.

Age 14-16

By this age, pupils should be using sensors as scientifictools in investigations and projects. They should develop

the skill to use two different sensors at once and plot onevalue say, pressure against temperature. They shouldexamine data critically and if the data logging software israther limited, they might learn to put the data into aspreadsheet. Combining data, graphs and text in a wordprocessor report is another important skill. For control workpupils might develop a control system using sensors (pushswitches or light sensors) and output devices (heaters,buzzers, lamps). In some courses, they would be expected toplan, design, make, test, evaluate and document their project.

Age 18-

Pupil's skills should be put to full use at this age, althoughsooner would be much more useful. They should be able

to choose their measuring tools, analyse data, criticise anddocument their work on the computer.


Section

1Introduction

10

If the computer has an analogue port, you can often connect sensors directly to this

Serial port to connect the interface to

Sensor

Interface with its ownanalogue to digitalconvertor.

Dataloggingsoftware

Sensing glossary

Light gate - (or timing sensor) a lightsensor which responds rapidly to lightchanges. Used for timing events withgreat accuracy.

Light sensor - measures the light level.Use for monitoring sunshine ormeasuring the reflection of light froma surface.

pH sensor - measures the acidity andrequires a glass pH electrode. Use formonitoring titrations or reactionscausing a pH change.

Position sensor - measures the angle ofmovement - in contrast to a distancesensor which works like a Polaroidcamera's electronic rangefinder.

Serial Port - a socket on a computerwhere you may connect an interface.Sensors connect to the interface. Data loggers also use other ports,such as USB or SCSI or Bluetooth.

Sound sensor - measures the soundlevel. Use to study sound travel andsound proofing. Sound is measured indecibels.

Temperature sensor - measures howhot something is. Use to study cooling,heating, insulation and the weather.

Time graph - a way of showing howsensor readings change over a periodof time.

Analogue to digital convertor - part ofa computer interface which convertsan analogue reading from a sensorinto a digital reading which thecomputer can interpret.

Analogue Port - a socket on a computerwhich you may connect analoguesensors to directly.

Analogue sensor - a more useful sensorwhich has many states and can providereadings over a wide range of change.

Digital sensor - a sensor or switch whichhas two states, on or off.

Data logging software - software whichis designed to record and display thereadings from sensors. Usuallysupplied specifically for your datalogging kit.

Data logging - collecting data fromsensors. To do this away from thecomputer you need a ‘data logger’.

Data logger - a self-contained device tocollect readings from sensors awayfrom the computer. When all thereadings have been taken you connectthe data logger to the computer totransfer the readings.

Interface - a device to connect thesensors to the computer.


Section

2Ideas

11

Ideas for data logging and control

An overview of the many applications forsensors in science, first listed by subject

and then, alphabetically, by topic.Other sections of this book take many of theseideas and work them through in greaterdetail.

Biological topics Chemical topics Page 21 Physical topics Page 23

See also:

Introducing data logging Page 33Exploring science with sensors Page 52Sensing for ages 14+ Page 73Sensors and software Page 120Index


Section

2Ideas

12

Adaptation: keeping warm

Temperature sensors

Animals huddling in cold weather,the size

of elephants’ears and thesize of a dog’stongue areexamples ofanimaladaptation toadversetemperatures.These can beinvestigatedusing temperature sensors.Huddling: make a bundle of test tubesand fill them with hot water. Placetemperature probes in tubes near thecentre and the edge. Then monitor howfast they cool. Repeat with the test tubesarranged separately.Elephant / dog: fill two cans with hotwater, make ears or a tongue out of foiland attach this to one can. Place these infront of a fan, put a temperature probe ineach and compare the rates at which theycool.

Water Pollution

Oxygen sensor

The biochemical oxygen demand, orBOD, is an indicator of water

pollution. Place a sample of river or pondwater in a flask. Push the oxygen probethrough a bung which fitsthe flask. Then place thisin a water bath andmeasure the oxygenlevel overnight.

Animal behaviour

Light sensor, Temperature and/orsound or infra-red sensor

Some animals are nocturnal or theyshow a regular pattern of activity.

Sensors can harmlessly monitor animalactivity overnight or over several days.Place any of the above probes in ananimal cage and monitor the animal’sactivity over time. The temperaturesensor will indicate when a nest isoccupied, the sound sensor will pick upmovements or bird song. The light sensormight show how often an exercise wheelis used.The light sensor can also be used in an

aquarium showing (in two separateattempts) whether fish prefer one side ofthe tank to the other. Since the lightsensor gives an indication of when it isday or night it can be used (perhaps withthe temperature sensor) to show if theanimals are busier during the day or thenight.For an extracurricular activity: use aninfra-red sensor to monitor themovements of the cat going through thecat flap during the night.

Biology

O2


Section

2Ideas

13

Bird feeding

Position sensor

Birds respond to the appearance offood no less than we do. If we set out

some dyed food on aposition sensor we canmonitor how often theyvisit it. Connectthepositionsensor toa remotedatalogger. Fixthe sensor on astand with aspring and a bagof bird food. Setthe data logger torecord (i.e. count) anevent each time the sensor reads above acertain value. When the data istransferred to the computer a bar graphwill show how often the sensor wastriggered. Repeat this using bird fooddyed different colours.

Breathing

Position sensor and spirometer

A spirometer is a ‘breathing box’where the lid rises and falls as you

breathe. It can be used to show the rateand depth of breathing, the tidal volumeand maximum expiratory volume. Itnormally connects physically to a chartrecorder which records the breathingmovements. However, aposition sensor has a leverarm which canreplace that chartrecorder. Thecomputer graph can be the subject ofsome interesting work.

Breathing air

Oxygen sensor

The air we breathe out contains only afraction less oxygen than the air we

breathe in. An oxygen sensor can showthis, as well as showing what happenswhen we re-breathe the samesample of air. Allow anoxygen probe to stabilise atroom temperature. Get asteady graph of theoxygen level on-screenand breath on thesensor. Place the prode ina carrier bag and takereadings whilst re-breathing the air in thecarrier bag. Fill another bag with nitrogenor carbon dioxide and take an oxygenreading from this to show the reading of0% oxygen. Another idea: place a pHprobe in lime water and show the effect ofbreathing into it.

Breathing locust

Oxygen / Manometer sensor.

Cold-bIooded animals use moreoxygen as their temperatures

increase. Place a locust (or earthworms,maggots although this isn't very friendly)in a flask with the oxygen probe in abung. Use Soda-Lime/Potassiumhydroxide to remove the carbon dioxide.Place the solid or KOH soaked cottonwool under a mesh. Note the steady dropin oxygen level as you record, thenincrease or decrease thetemperature slightly andnote the effect on oxygenconsumption.Alternatively use amanometer sensor tomonitor the volumechanges as the locustbreathes.

Biology

O2

O2


Section

2Ideas

14

Breathing movements

Pressure or breathing sensor

Monitoring breathingmovements before

and after exercise showsus how our lungs canincrease their intakeof air. Strap abreathing sensoraround the chest. Oruse a stethograph witha firm plastic tube toconnect ir to a pressuresensor. Chest movements cause a changein volume/pressure which is recorded andshown on screen.Usually a great success, but it is hard tocontrol the position of the belt. Use anexercise cycle as this doesn’t disturb theposition of the belt round the chest. Makegraphs during resting, exercise andrecovery. Look for changes in breathingrate and depth. Show (semi-quantitatively) the tidal and maximumexpiratory volumes.

Energy release from seeds

Temperature sensors

Seeds use and release energy as theygrow. By placing seeds in a vacuum

flask we can ensure that this energy is notlost to the environment but insteadproduces a noticeable temperature rise.Place temperature probes in two vacuumflasks, one with live germinating seedsand one with killed seeds. Monitor thetemperature over several hours. Use adata logger if you wish.

Energy release from food

Temperature sensor

We release energy fromfood by oxidising it to

carbon dioxide andwater. If we burnfood we perform asimilar chemicalreaction. If we usethe energy released to heat ameasured amount of water we can, inturn calculate the energy content of food.Set up a temperature probe in a boilingtube with a measured amount of water.Burn a measured amount of food (abiscuit, a peanut) and monitor thetemperature rise. Even if the foodextinguishes prematurely, there will stillbe a clear graphical record of the totalenergy rise provided by the food. Use theprogram to read off temperature valuesfrom the graph. Calculate the energyreleased.

Energy & microbial activity

Temperature sensors

Bugs use and release energy as theyrespire. By placing cultures in

vacuum flasks we can ensure that thisenergy produces a noticeabletemperature rise. Place temperatureprobes into yeast cultures (one culture hasbeen boiled) in 2 vacuum flasks. Monitorthe temperature over several hours usinga data logger.Monitor the temperature of a hay stack, acompost heap, a beehive or ant-hill. Use a

data logger and place atemperature probe in thesample and another in theopen air.

Biology

oC

oC

oC


Section

2Ideas

15

Environment

Light, sound, rotation, pressure etc.

Sensors make the job of monitoring theenvironment an easy one. The

applications are as diverse as theenvironment itself.Connect the sensors to a remote datalogger. Check the conditions inside agreenhouse or monitor the weather.Measure the light reaching the groundand relate this to the amount ofvegetation there. Use oxygen and pHprobes in a pond or aquarium to studythe changing oxygen and (indirectly)carbon dioxide levels. Use a rotationsensor to measure the water flow at themiddle and at the banks of a stream.Use a sound sensor to find when the roadtraffic is busiest, or to find when the birdsstart to sing. Use a position sensor as amakeshift ‘anemometer’. (Connect thesensor to a spring and a plastic windvane.)Energy conservation is good for theenvironment - so let a data loggermonitor the heating or heat loss from theschool buildings.You might even use an air pressuresensor on a school journey to a mountaincentre - it can show changes in pressurewith altitude.Use a pH sensor to study the pH ofstream water, soil or rain.

Enzyme activity I

Light sensor

The light sensor can be used tomonitor a change in colour or

turbidity. For example, amylase acts onstarch in the presence of iodine to give acolour change from blue to colourless,trypsin acts on casein protein to producea change from cloudy to clear. Similarlyboth pepsin and the proteases inbiological washing powder act on albuminto produce a change in turbidity.Use the sensor to assess theeffect of differentconcentrations andtemperatures onenzyme activity.Find out justhow heat-stablewashing powderenzymes are.Finally, if youare doing anenzyme extraction thistechnique is better thanmost for assessing the yield.The reaction mixture isplaced in a glasscontainer, and the lighttransmitted through the solution ismeasured continuously. The enzymeactivity is related to the slope of thegraph. It helps if you split the reactionmixture into two - one part goes in the‘cuvette’ the other can be placed whereeveryone can see the change taking place.You can use postal tubing or aluminiumfoil to make a colorimeter cell. Thisensures that light passes through thesolution. I’ve not heard of anyone goingas far as using a filter to produce amonochromatic light source - but it’s anidea to follow up.

Biology

Light sensor


Section

2Ideas

16

Enzyme activity II

pH sensor

The pH sensor can beused to monitor the

speed of changesinvolving pH. Forexample, urease actson urea to produceammonia, lipaseacts on lipid to produce fatty acids. Thereaction mixture is placed in a container,and the pH of the solution is measuredcontinuously. The enzyme activity isrelated to the slope of the resulting graph- but use the initial rate of reaction foryour measurements (that’s the first part ofthe graph). There is an inherent problemwith the technique - the pH changedecreases the enzyme activity - but that isa good teaching point.Repeat the measurement at differentconcentrations and temperatures asrequired. If you are extracting theenzyme this technique is better than mostfor assessing the yield.

Fermentation

pH sensor & or oxygen sensor

During microbial respiration, acids areproduced as waste products.

Lactobacilli turn lactose to lactic acid,yeast turns sugar into alcohol and thealcohol in wine is oxidised to ethanoicacid (though this is not necessarily due to

microbial activity). Setup a culture such asmilk and live yoghurt,or yeast and sugar.Monitor the change inpH or oxygen levelover several hours orovernight. Use a flask

in a water bath, and suspend theelectrodes in it. Seal the neck of the flaskwith polythene and an elastic band.Repeat at a different temperature.

Food: cooking and freezing

Temperature or thermocouple sensor

oC

Some temperature sensors can recordthe very high temperatures while

cooking food in an oven. You can use oneto answer the question: does putting foilon jacket potatoes make any difference tohow they cook?Use a high temperature probe to showtemperatures at the top and bottom of theoven or in parts of a cooking cake.Investigate how long you need to leave afrozen sausage to thaw or compare theeffectiveness of different vacuum flasks.For this you can use ordinarytemperature probes. For the sausageexperiment, place one probe in themiddle of the sausage, and the other nearthe edge. Freeze the sausage and probestogether, and then allow them to thaw. Ifyou use a data logger, you can easilymonitor both the freezing and thawingprocess.

Biology

pH

pH

O2


Section

2Ideas

17

Homeostasis

Data logging and control

Medical technology such as kidneymachines, lung machines and baby

incubators involve control technology.Models of these devices can be madeusing appropriate sensors and devices.Lung machine: use an oxygen sensor anda device to pump air from a large bag of‘oxygen’. E.g. use an aquarium pumppowered via a mains controller. Usecontrol software to write a program whichswitches on the pump when the oxygenlevel falls and switches off the pump whenit rises again.Baby Incubator: use a temperaturesensor, a heating device and a cooling fan.(The fan and heater can be powered witha mains controller or relay). Use controlsoftware to switch on the heater when thetemperature falls and switch off the fanwhen it rises.Study how effective a control system iswith just a fan and then with just a heater.How will the system behave in summerand in winter?See the Control section for further ideasand worked examples.

Lung / blood pressure

Pressure sensor

The pressure sensor can be used tocompare our lung

pressures. You can alsoconnect a sphygmo-manometer cuff to thesensor to give a graphicdisplay of whathappens when ablood pressuremeasurement istaken. For this,set the pressuresensor to its high range. Start the softwarerecording then put a stethoscope on thearm and inflate the cuff until the pulsestops. Adjust the sensor to bring thereading on screen. Next deflate the cuffslowly until you hear the pulse justcoming through - the screen should showthis. Finally, release the cuff pressure.Use the data logging software feature tozoom in on the arterial pulse wave egadjust the time axis.

Microbial growth

pH sensor &/or Oxygen sensor

Microorganisms respire and use upoxygen. Their rate of respiration is

affected by temperature. Set up a culturesuch as milk and live yoghurt or yeast andsugar. Monitor thechange in pH oroxygen level overseveral hours orovernight. Repeatat a differenttemperature orsugarconcentration.

O2?GO

STOP

Biology

kPa

pH

O2


Section

2Ideas

18

Osmosis

Manometer or Pressure sensor

During osmosis, water moves througha semipermeable membrane from a

hypotonic solution to a hypertonicsolution. The resulting volume changecan be measured using sensors. Anelectronic manometerconsists of a U-tube filledwith liquid. A pressuresensor, although lesssensitive, can alsorespond.Set up a dialysis bagfilled with sucrosesolution and place itin a beaker of water. Connect the openingof the bag to an electronic manometer orpressure sensor.

Photosynthesis

Oxygen sensor

Put some Elodea or a Chlorella culturein a flask of water. Fit an oxygen

probe through its bung. Measure theoxygen level over a period of an hour orso. Adding 5% sodium hydrogencarbonate provides extra carbon dioxidefor photosynthesis.Investigate the effect of different lightlevels by taking measurements with thelight source some distance away. Every 15minutes, move the lightcloser by the samedistance. Alternately, showthe effect of light ofdifferent colours byplacing filters in front ofthe light source.

Plant growth / Tropism

Position sensor

A position sensor can be made to move as a plant grows and this

movement can be recorded. Tie a piece ofthread to a fast growing plant. Connectthe thread to the position sensor. It maybe possibleto see if aplantgrowsfasterduringthe day orduring the night - so set up alight sensor at the sametime. It is also possible toshow phototropism bymeasuring how fast a planttakes to respond to a change oflight direction.The position sensor can bemounted upside down to getthe graph to rise, rather thanfall, as the plant grows. A datalogger is particularly useful here - it willallow you to record over an extendedperiod of time.The sensitive plant, Mimosa Pudica makesan interesting subject using similarapparatus. For this investigation touch theplant’s leaves and the graph on screen willshow how long it takes for the plant torecover. Repeat this in the dark andattempt to explain the slower speed ofrecovery.

Biology

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Pulse

Pulse sensor

Study the effectof exercise on

the pulse rate.Show how quicklythe pulse returns tonormal after exercise.The pulse sensor has a probe which clipsto the ear lobe and gives a continuousread out of the pulse rate.The sensor may have an outlet whichprovides a trace of the pulse itself. Inother words, rather than showing thepulse rate, it shows the blood flowthrough the ear.

Reaction time

Light gates for timing

The computer can start its own ‘stop-clock’ when an object passes in front

of a light sensor and stop the clock as itpasses a second sensor. This requiressoftware especially designed for timing.To measure reaction time, give twostudents a light sensor each.Ask one to place their handin front of the sensor andget the other to do thesame immediately after theysee this happen. Take a series of readingsto show if the reaction time improves withpractice. As a variation on the idea, getthe second student to turn away so thatthey have to react when they hear asound.It may be possible to measure the speedof the ‘knee-jerk’ reflex and it is certainlyfun to try. Place one light sensor near theknee to ‘see’ when the knee is hit. Placeanother sensor near the foot to ‘see’ whenit reacts.

Soil and pond temperature

Temperature sensors

The life forms at different levels in theground or in a pond need to adapt to

greater or lesser temperature changesduring the course of a day. Connecttemperature sensors to a remote datalogger. Monitor the temperature of theground at different depths - both duringthe day and overnight. Expect the deeperprobes to show a slower and shallowertemperature change.

Using the same set up, monitor thetemperature gradient in a pond over

a 24 hour period.It is possible to show the temperaturegradient in a pond. This simply involvesmeasuring the temperature continuouslywhilst slowly pulling the temperatureprobe up from the bottom of the pond.Alternatively, set the data logger to take areading each time a key is pressed. Thenposition the probe in the pond, press thekey, move the probe, press the key and soon.Extend the investigation to show howlight levels vary with depth in the pond.

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Biology

Transpiration

Humidity sensor / Balance

Plants transpire - evaporating water atthe leaves to draw water and minerals

in from the roots. This can be monitoredusing a humidity sensor. Simply, place ahumidity probe in a polythene bag with aplant and monitor the humidity.It would be nice to be able to show whichside of a leaf loses the most water - but todate I’ve not found out how to do it.Using an electronic balance attached tothe computer it becomes possible tomonitor the loss of water by transpiration.It can also show the effect of roomtemperature on this and the effect ofplacing the plant in a sealed polythenebag. You will need a balance designed tolink to your computer, a cable andcompatible software.

Weather

Temperature, light, rotation, humidity,pressure sensors

Sensors make the almost impossible jobof monitoring the weather an easy

one.

Dedicated weather monitoring kits areavailable and they do the job effectively.They may however, be in excess of youroccasional need to ‘do weather’.Connect the sensors to a data logger. Usea position sensor as a makeshift‘anemometer’. Connect the sensor to aspring and a plastic vane. (Alternatively,fit a vane to a rotation sensor to measurethe wind speed). The light sensor recordsthe occurrence of day / night andfurthermore shows the amount ofsunlight and cloud cover. See if you canrecorf a cold front blowing over.

A key part of monitoring the weather is the analysis of the data, so if you can

get the data you collect into a spreadsheetor database file, the whole group canwork on it - presenting it in various graphformats and looking for patterns. Forexample, find out if it is always cold whenit is wet or windy or see whether it reallydoes get cooler before it starts to rain.


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Acidometry

pH sensor

The pH sensor replaces a pH meterand can monitor the progress of acid-

base reactions. In an acid-base titrationthe acid is dripped into alkali from aburette and the pH is monitored. Thereare two approaches to this - the semi-quantitative approach simply involvesmonitoring the pH against time as theacid drips from a burette. This make theassumption that the flow rate of the acid isconstant. Or there is the quantitativeapproach where you enter the the volumeof acid using the keyboard. During thetitration, you add acid bit by bit and typein the amount added at each point. ThepH is measured for you. In this way, it isquite easy to prepare a set of impressiveacid-base titration graphs.

Chemical change

Temperature sensor

Is there an energy change when plasterof Paris sets? Or: which mixture of lime

and sugar makes the best heat source?Thecomputer display of rising temperaturesprovide graphic evidence of theseexothermic reactions.

Chemistry

Light sensor

Colorimeter

Light sensor

The light sensor can beset up as a

‘colorimeter’ tomonitorreactionsinvolving aprecipitation ora colour change.These includethe hydrolysis ofbenzenediazonium chloride(colour change), thereaction of iodine withpropanone (colour change),determining the formula of acomplex ion (colour change) or thereaction between thiosulphate and acid(precipitation).

Combustion

Oxygen, humidity, temperature andlight sensors.

During combustion oxygen is used,water is produced and heat and light

energy given off. All these changes can bemonitored electronically. So you can placeprobes in a bell jar with a burning candleand record for a few minutes. Then, whenthe candle extinguishes, re-admit air tothe bell jar and note the increase inoxygen level.

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Conductimetry

Conductivity sensor

Change in a solution’s conductivity isused as a measurable feature in some

reactions. For example when bariumchloride is added to sulphuric acida precipitation occurs with aconsequent decrease in the

conductivity of thesolution. This can bemonitored using aconductivity sensorwith the productionof a very good graph.

The conductivity sensor also provides ameasure, if non-specific, of water purity orsalinity of rock pools.

Energy from fuels

Temperature sensor

During the combustion of a fuel, heatenergy is given off. In the activity

illustrated, the energy released heats ameasured amount of water - allowing youto calculate the energy content of the fuel.Set up a temperature probe in a boilingtube with a measured amount of water.Burn a measured amount of fuel (acandle, a spirit burner, metaldehyde,wood) and monitor the temperature rise.Read off temperature values from thegraph and calculate the energy released.A high temperature probe would allow youto compare the combustion temperaturesof fuels.

Gas in fizzy drink

Position sensor or balance

How much gas is there in a can offizzy drink? How does temperature

affect the loss of gas? Does keeping anopened can in the fridgehelp to keep it fizzy?Use a position sensorto investigate.Place the positionsensor on theplunger of a gassyringe and monitorthe loss of carbon dioxide from a fizzydrink.You can also use a balance to monitor thechange in mass. You will need a balancedesigned to link to your computer, asuitable cable and software.

Gasometry

Position or manometer sensor

Place a position sensor on the plungerof a gas syringe and use it to monitor

the progress of any gas evolving reaction.As examples try the reaction betweenmarble and acid (e.g. acid rain), thedecomposition of hydrogen peroxide andthe loss of carbon dioxide from say, a fizzydrink.For reactionsinvolvingmuch smallervolumes ofgas, apressuresensor canbe used.Forexample you can use one to monitor theuse of oxygen by rusting iron.

Chemistry

Position

Conductivity

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Gravimetry

Electronic balance

The rates of some reactions can bemonitored by the change in mass that

occurs due to gas evolution. Youneed a balancedesigned to link toyour computer, acable and software.You can study thereaction betweenmarble chips andacid; the decomposition of hydrogenperoxide; the water uptake by silica gel orthe specific latent heat of vaporisation ofwater. Explore the factors which affect therates of reactions such as differentcatalysts, the amount of catalyst, particlesizes and concentrations of reactants.

Thermometry

Temperature sensor

The computer display of rising andfalling temperatures provides graphic

evidence of exothermic and endothermicchanges. Use a temperature sensor tomonitor a thermometric titration,measure heats of solution, the heatevolved in polymerisation or in thehydrolysis of organic halogen compounds.

Absorption of thermalradiation

Temperature, thermocouple or IRsensor

Differentsurfaces,

black, whiteand shinyabsorb heatradiationdifferently. Thesubtle changes intemperature arefairly easily shownusing electronicsensors. The threekinds of ‘heat’ sensor available are usedslightly differently:

Temperature sensors: place the probein a black painted calorimeter with

water. Use a second probe in a similar butwhite painted calorimeter. Start recordingand allow the temperatures to equilibrate.Finally move a radiant heat source intoposition, mid way between them.

Thermocouple: use differentialtemperature probes - place one probe

in a black painted calorimeter with water.Place the other probe in a similar butwhite painted calorimeter. Set the sensorrange to a low setting. Start recording andallow the temperatures to equilibrate.Finally move a radiant heat source intoposition, mid way between them. As asimpler alternative, place the two probesunder black and white painted metalsurfaces.

Infra Red Sensor: Use the sensor totake readings of radiation at various

distances from the source. Alternatively,take readings of radiation reflected fromthe surfaces.

Chemistry / Physics

Temperature

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AC ripple

Light sensor

The fast data capture ability of thecomputer and fast data loggers can

pick up the flickering of a fluorescentlamp. Point the sensor at a fluorescentstrip lamp. Set the data logger to recordas fast as possible. The graph will show theflicker and a simple count will indicate itsfrequency.

Battery life

Voltage sensor

Different electrical cells exhibit quitedifferent deterioration characteristics.

For example, nickel-cadmium cells worksteadily and suddenly stop dead. Othersdecay steadily to the end. This data isuseful for matching battery types to theirfinal application.Set up a circuit with a battery dischargingthrough a lamp.Connect avoltage sensoracross the lamp.Monitor the p.d.as the batterydischarges. Tryagain using othercells such asNickel-Cadmium,Alkaline, Lithiumand Lead-Acid.Some people saythey can revive abattery by placingit under their pillow overnight. Investigatethis idea.

Physics

Voltagesensor

Temperature

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Capacitor discharge

Voltage / current sensors

The charging and dischargingcharacteristics of a capacitor can be

shown very clearly using electronic voltageand current sensors. The computercaptures this fairly rapid event, anddisplays it as a graph for further study.Set up a circuit with a power supply,switch, resistor and capacitor inseries. Connect the voltage sensoracross the capacitor and put the currentsensor in series with it. Monitor the p.d.and the current as you charge anddischarge the capacitor.

Cooling Curves

Temperature sensors

As a pure substance changes fromliquid to solid there is a loss of heat.

However, at the melting point, thetemperature hardly changes.Monitor the cooling of stearic acid,benzophenone or wax in a test tube with atemperature probe. You can use a secondprobe - placing it in a small beaker ofwater with the above apparatus. In thisway you will see how the beaker of waterwarms as the substance in the test tubecools. This provides evidence to helpexplain the latentheat of fusion.A high temperaturesensor wouldallow you tostudy themeltingpoints ofmetals.


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Physics

Light

Position

Ohm's Law


Set up a circuit with a power supply,rheostat and resistor. As the current

through the resistor alters, the p.d. acrossit also changes. If the various currentvalues are plotted against the p.d. weobtain the relationship called OhmsLaw. Other electronic componentsshow different behaviour. Theserelationships are shown easily, rapidlyand graphically using sensors.Set up a circuit - as above. Connect thevoltage sensor across the resistor and thecurrent sensor in series with it. Monitorthe p.d. and the current as you move therheostat slider. By plotting p.d. againstcurrent you should obtain a graphcorresponding to Ohms Law. Try againusing a resistor (with twice the value), alamp, a Silicon diode and a Germaniumdiode.Results: for the second resistor thegradient of the p.d. v current graph willbe different. The lamp will ‘break the law’indicating that its resistance changes withtemperature. The diodes will only conductabove a certain voltage - but take care notto overload them.If you have a fast data logger use its fastrecording feature to measure the currentsurge when you switch on a lamp.

Voltage

Current

Interference patterns

Light sensor, position sensor

The light sensor can be used toprepare a graph representing the

diffraction and interference patterns. Alaser is directed through a slit and theposition of the light probe is alteredsteadily. The experiment can be repeatedusing a multiple slit.Direct the laser at the light probe. Startrecording and move the probe at a steadyspeed across the pattern. The experimentcan be extended so that youmeasure the distancethe probe is moved.The position sensormonitors the

movement of the light probe. (You will, ofcourse, have to calibrate this movementfirst.) Attach the light probe to theposition sensor with a stiff piece of wire.Start recording and move the probe asbefore. After the recording, you should beable to plot the light intensity against thedistance moved.

Elasticity

Position sensor

A position sensor can be attached tovarious kinds of thread and masses

attached tomeasure theelasticity of thethread.

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Expansion

Position sensor

Do different metals expand at thesame rate? Get metal bars of the same

dimensions. Fix one end in a bench viceand let the other end rest on the lever armof a position sensor. Start recording whenyou begin to heat the metal bar. Thisshould produce a graph showing theexpansion of the bar. Repeat using othermetals.The position sensor can also show theexpansion of the air in say, a balloon. Placea filled balloon in a fridge to cool. Removeit and place it on the bench with a positionsensor attached to it. Start recording - thegraph will show the expansion of the air inthe balloon.

Distance - time

Distance / motion sensor

The distance or motion sensor is apowerful tool for measuring distance

and exploring distance-time relationships,acceleration, and kinetic energy.Intriguing investigations to try includedesigning and evaluating a model skijump and studying stopping distancesunder different conditions.

Freezing point

Temperature sensors

Why do they put salt on the roads?Investigate the

effect of salt on themelting of ice. Take twobeakers of ice and place atemperature probe ineach. Start recording thetemperature and add saltto one of the beakers.Does the ice melt faster?Does the temperaturechange?

Gas (oxygen) solubility

Temperature / oxygen sensor.

The solubility of oxygen in waterdecreases with increasing

temperature. This is of special significanceto life in water. The response of an oxygenelectrode itself varies with temperature soyour sensor will need to compensate forthis.Place the thermistor, oxygen probe andtemperature probe in a flask of water.Place the flask in a water bath and monitorthe temperature and oxygen level.Increase the temperature of the water andthen allow it to cool. If the solubility ofoxygen decreases with increasingtemperature, does theoxygen level increaseagain as you let itcool?

Physics

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Forces

Light gates for timing

The computer can start an internal‘stop-clock’ when an object passes in

front of a light sensor and stop the clockas it passes a second sensor. This requiressoftware especially designed for timing.Free fall: To measure the time an objecttakes to fall, use clamps to fix one sensorat a high point and one at a low point. Setup the software to record and then dropthe object. Get the software to calculatethe acceleration due to gravity.More forces: There are numerous scienceexperiments using ramps and the linearair-track. Ticker-timers have been used inthe past but the Timing sensors are awelcome replacement. Use clamps to fixthe timing sensors at each end of a ramp.Run a dynamics trolley or model car downthe ramp and time the event. Study theeffect of altering the angle of the ramp, ofaltering the height the trolley is droppedfrom or of changing the load on thetrolley. You can also use this set up toshow friction - measure the time take forobjects, such as trainers/shoes, to slidedown different surfaces.

Using timing sensors you caninvestigate which is the best shape

for a boat. Use a length of plasticguttering filled with water. Attach threadto a boat and pass this to a pulley andweight at the far end of the gutter. Fix upthe timing sensors to see how fast differentboats travel.At a higher level, you can show Newton'ssecond law of motion. Use slotted massesand a pulley to pull a trolley along a rampwith a slope sufficient to compensate forfriction. First measure the acceleration ofan unloaded trolley with say 250g hangingfrom the pulley. Then repeat themeasurement, each time moving a massfrom the pulley to the trolley. This keepsthe total mass the same. A range of other

advancedinvestigations withtiming sensors willallow you toshow theconservation ofmomentum,elastic collisions and recoil.Other investigations: If yougive the trolley a push, does itcontinue to accelerate after you let go? Ifyou drop a book and a pencil at the sametime, which would land first? Does theshape of an object affect how fast it falls?What makes a good parachute? Whichelastic band makes the best 'engine'?

Gravity

Position / force sensor

A position sensor can play the part ofan electronic balance or 'force sensor'.

The sensor is connected to a data loggerand the assembly taken to a passenger liftto show the effects of going up and down.Attach a spring with hanging masses tothe position sensor. Start recording as thelift rises and comesto rest. Continuerecording as the liftgoes down. A forcesensor (a modifiedbathroom scale) cando this moreelegantly.

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Gas laws

Temperature & pressure

We can show how pressure varieswith temperature: Place a

temperature probe in a water bath. Placean empty flask with a bung and a plastictube in the water bath. Connect the tubeto the pressure sensor. Increase thetemperature of the water bath as you

monitor the temperature and thepressure. Continue monitoring and allowthe water bath to cool. When finished,plot the pressure against the temperatureto show the relationship.A simple variation on this theme involvescomparing the pressure from a balloonmoved from a cold room to a warm room.Place the balloon in the fridge to cool.Later, connect the balloon to the pressuresensor and start recording as the balloongradually warms up.

Heat transfer

Temperature sensors

Most conduction, convection and radiation experiments can be

radically improved by using temperaturesensors. It is quite easy to adapt thenumerous experiments on this theme forthe computer.Conduction along strips of metal: tapethe probe to the end of a metal strip andheat the other end in hot water or aBunsen flame.Conduction: compare the cooling of alarge saucepan of water with a smallsaucepan of water. Similarly, compare howfast they heat up. Suppose you are makinga cup of coffee, the water boils and thephone rings. Should you pour the waternow or after the call?

Conduction: which gets hotter in the sun,the grass, a metal seat or a concrete path?Use a data logger and sensors to monitorthe temperatures on a sunny afternoon.

Convection in liquids: use twotemperature probes, place one at the

bottom of a beaker of liquid, the other atthe top. Heat the beaker and monitor howthe temperature ofeach probe changes.Conduction/convectionin air: agood contextfor this is‘keeping yourhouse

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warm’. Get a cardboard model house andplace temperature probes high up / lowdown in the house.

Insulation: Use two temperature probesto compare insulating fabrics, different

socks or gloves, containers for keepingdrinks hot and containers for keeping apicnic cold. Does a carrier bag help keepyour take-away warmer? How do differentvacuum flasks compare?Radiation: see Absorption of thermalradiation.

Cooling by evaporation:

Temperature sensor

Compare the cooling effects of waterand alcohol. You can compare the

cooling curves of evaporation of differentliquids in contexts such as: do after-shaveand perfume really make your skin cold -or does it just feel cold? Or: should youfeel colder out of the swimming pool thanyou did in it? Or, what good doessweating do? Should wet gloves really feelso much colder? Would plastic gloveskeep our hands warmer? In this lastexample, compare the cooling of wetgloves, dry gloves and wetgloves covered in aplastic bag. Placetemperatureprobes in thegloves and use afan to simulate a coldbreeze.

Heat and electric current

Voltage, current and temperaturesensors. IR sensor.

You can investigate the temperaturechange when a measured amount of

water is heated by a measured amount ofcurrent. Set up a circuit with a powersupply and low voltage heater unit in abeaker of water. Connect a voltage sensoracross the heater unit and a current

sensor in series with it. Record thetemperature, the p.d. and the current.You can stop after very short period oftime, since the computer will have takenmany readings. Get the program to readvalues off the graph.You can also check the efficiency of a solarcell - relating its output to thetemperature. The setup would be similarto the above - less the heater unit andbeaker.The special sensitivity of an Infra Redsensor can be used to monitor the heatgiven off when a fairly small current passesthrough a wire.

Physics

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Magnetic field

Magnetic field sensor

A magnetic field (or magnetic fluxdensity) sensor features a sensitive

Hall probe. This can be used to study thestrength of a magnetic field with distance,to compare magnets and electromagnetsand to show the change in magnetic fieldas the Hall probe passes through a coil.Three kinds of measurement can beattempted. Firstly a simple ‘spot’measurement of the magnetic field.Secondly a measurement of the fieldagainst distance. You type the distance inat the keyboard. (For this you set up thesoftware keyboard entry.) Thirdly ameasurement of the field while you movethe probe steadily through a coil. (For thisyou record the magnetic field againsttime.)

Induction

Voltage (pd) sensor

Connect a Helmholtz coil to a voltagesensor. Set up a data logger to record

as fast as possible andto start recordingonly when there is achange in voltage.Finally, drop amagnet throughthe centre of thecoil. You mayneed to add anegative bias tothe sensor input to allows anegative voltage to berecorded.

Light energy

Light level sensor

Investigations to try: Compare thebrightness of different light sources -

which would be best to read by at night?How does the light level change withdistance from a light source? Which pairof sunglasses appears to be the mosteffective? How fast do photochromiclenses change?Compare the light reflected from differentfabrics -which wouldbe safer for acyclist towear atnight?Comparethe lighttransmittedthroughdifferentmaterials - which of them would be bestfor a window blind?

Physics

Magneticsensor

Lightsensor

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Oscillation of a springor pendulum

Position sensor.

Monitor the oscillation of a spring orpendulum by attaching a moving

spring or pendulum to a position sensor.This will allow the study of simpleharmonic motion. You can show how thefrequency is unaffected by the amplitudeof the movement or by damping. Usingthe mathematical utilities of the datalogging program you can derive furthergraphs to show the velocity and the kineticenergy of the moving mass.An interesting extension involves forcingthe mass to vibrate by using a coilpowered by a signal generator. The massin this case will need to be a magnet andthe investigation can show the system’sresonant frequency.

Physics

Positionsensor

Radioactivitysensor

Radioactivity

Radioactivity sensor

Radioactivity sensors use a Geiger-Muller tube. You can quickly, and

safely prepare a decay curve using aprotactinium generator. You can studythe statistics of decay, calculate half-livesand show the effect of distance on thecount rate (inverse square law). For thislast investigation, you need to get thesoftware to accept distances typed at thekeyboard.You can achieve a very gooddemonstration of radioactive penetrationby getting the computer to display agraph whilst you place different materialsbetween the source and the GM tube.


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Physics

Temperaturesensor

Soundsensor

Sound and sound travel

Sound sensor

The sound sensor allows a range ofinvestigations into sound travel,

sound pollution, sound proofing andsound decay with distance from a soundsource. Using fast recording options onthe computer youcan prepare agraph of the attack,decay, sustain,releasecharacteristics ofdifferent sounds.When you use adata logger andrecord as fast as possible, the sound sensorcan show the sound wave and also recordvoice patterns.

Spectrum

Ultra-Violet / infra-red sensor

Use the infra-red sensor to detect theinfra-red at the end of the visible

spectrum.Use the ultra-violet sensor to detect UV,to compare the transmission of UVthrough glass, plastic and quartzor to compare sunglassesand sun creams.

Solar Power

Temperature sensor

Build a solar collector using anumbrella lined with foil. Use the

temperature sensor to monitor itseffectiveness. For out-of-doors work plugthe sensor into a data logger. Position thetemperature probe tip at the focus of thecollector and record the temperaturechange. Compare the effects of differentreflective materials. You’ll need torepositiontheumbrellaif youwish torecordthroughoutan afternoon.

Ultra-violetsensor

Introducing data logging to ages 10-13


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In this section there are a number of introductory'investigations' using sensors. Investigations are an entirelysuitable kind of activity for using sensors.Each activity is a double page spread, one side withteaching notes, the other with a guide that is set out as aworksheet. The details and questions are provided purelyas a 'jump-start'. Clearly, if your students are already fairlyskilled in investigative work you will want to cut-out orcover some of this detail to avoid giving the game away. Inall cases, the pages are intended as starting points to beused as appropriate. The activities are widely applicableincluding use with the most basic software.

The first side of the spread is the teacher's guide: Information on the science in the activity. Requirements - a detailed equipment list. Introducing the Activity - some talking points. Investigate - some practical advice. Results and outcomes - expected results. Apply - extension activities.The second side of the spread sets up a context for theactivity, lists the things needed and suggests a method ofinvestigating. Wherever appropriate you will find anexample table to record the results and some questions tointerpret them. Finally, the apply section sets new tasksusing the skills developed so far.

Temperature sensor activitiesKeeping baby warm. About heat transfer.How can we keep warm? About heat insulation.Making your hot drink cool. About heat travel.Sound sensorCan you trust your ears? About loud and quiet.What can sound travel through? About sound travel.What's the best way to stop sounds? About soundproofing.Light sensorWhich light is the brightest? About light sources.What should a cyclist wear? About reflection of colour.Stopping light from a window. About light transmission.

See also:

Ideas for datalogging Pages 11-32Exploring science with sensors Page 52-61

Teachers notes


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Investigate

The investigation compares the cooling ofcontainers filled with hot water. Dress thecontainers like a baby and an adult.You may need to do two separate runs,one for each container. To help comparethe two time graphs, ensure that bothstarting temperatures are similar andrecord for the same amount of time. 15minutes should be fine.

Results and outcomes

Place or trace one of the two time graphsover the other. The smallest container ofhot water will coolfaster than thelargest containerand show a lowerfinal temperature.Note the steeper fallin the time graph.

Apply: more to do

How do elephants keep cool? Elephantsuse the surface area of their large ears asheat radiators. In hot weather elephantsincrease the blood supply to the ears andflap them about to lose body heat. Usealuminium foil to wrap a can of water andto make two large elephant ears. Measurehow fast it cools.You might also use a spreadsheet as acalculator to show how surfaceareas changewith size.

Human beings, babies and adults alikeare warmer than their surroundings andconstantly lose heat to it. Other thingsbeing equal, the speed at which they loseheat depends on shape, the layer of fatbeneath the skin and the surroundingtemperature. The more skin in contactwith the surroundings the faster the lossof heat. Animals can stay warm longer byhuddling or curling up into a ball whichhas a smaller surface area.A baby is more prone to heat loss: it has agreater surface area for its size comparedto an adult. Insulating materials, such asblankets, slow down the baby’s loss ofheat.

Requirements

Large and small metalcontainers - decorate themas ‘baby’ and ‘adult’.Temperature sensor,interface, computercable, software.Computer, printerand monitor. Safetynote: use hand hotwater, place thecontainers in a bowlor tray. Also:aluminium foil.

Computer

Interface Sensor

Introducing the activity

Ask the group how they would dress asmall baby for a visit to the park. Wouldthe baby need to have more covering thanthemselves? Is a baby more sensitive tocold? Does a baby get colder faster than anadult? How might we investigate this?

Keeping baby warm

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The IT in Science book of Data logging and Control 35

Have you noticed that small babies always get wrappedup well. Do they need more covering than you do?In this activity you will compare a small‘baby’ and a larger person. Who do youthink will get colder first?

1. What was the temperature ofyour ‘baby’ at the beginning?2. What was the temperature ofyour ‘baby’ after fifteenminutes?3. What might happen to thebaby’s temperature if you leftit a long time?4. Where do you think thebaby’s heat went to?5. What was the temperature ofa larger person after fifteenminutes?6. Look at your graphs. Whichloses heat faster, a small babyor a larger person?7. Can we dress a baby in ‘toomany clothes’?

Apply:

· Does wrapping a baby in ablanket help to keep it warm?· How do elephants keep cool?

You need

Care! You will be using hotwater. Make sure it does notget knocked over.Hot water, a large and asmall container, a‘blanket’. Computer,printer and the temperature sensor.

Investigate

1. Get the computer ready tomeasure temperature.

2. Fill the small container with hotwater. The small container is awarm baby. Take and record itstemperature.

3. Get the computer to draw a timegraph as it cools down.

4. Stop the recording after fifteenminutes. Now print the graph.

Now see if a larger person keepswarmer:

5. Fill the large container with hotwater. The large container can beyou. Take the temperature. Makesure the temperature is the sameas the baby was to start with.

6. Get the computer to draw anothertime graph as it cools down.

7. Stop the recording after aboutfifteen minutes. Print the graph.

Temperature sensor

Keeping baby warm

Computer

Interface Sensor

Teachers notes


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C lothes provide an insulating layerbetween the body and the surroundings.Air is a good insulator anda poor conductor of heat.The air trapped withinclothing providesprotection against heat loss.Depending upon how muchair is trapped, bulky sweaters or manylayers of thin clothing provide insulation.

Requirements

Plastic or metalcontainers, pieces offabric, decorate thecontainers as ‘people’. Temperaturesensor, interface, computer cable,software. Computer, printer and monitor.Also: aluminium foil; a fan to represent acold wind. Safety note: place containers in abowl or tray.


How would you dress for a walk in winter?How do people who work outside in coldweather dress? Are some fabrics warmerthan others? Would they be better off withone thick sweater or several thin layers ofclothing? How can we investigate this?

Investigate

The investigation compares the cooling ofcontainers filled with hot water. Wrap thecontainers loosely to make the insulationmore effective.You may need to do two separate runs,one for each container. To help comparethe two time graphs, ensure that bothstarting temperatures are similar andrecord for the same amount of time. 15minutes should be fine. If a fan is used tospeed up cooling, use it equally on eachrun through.


Place the time graphs over each other.The most effective insulator maintains thetemperature of the water longest - shownby the slower fall in the time graph and ahigher final temperature.

Apply: more to do

Astronauts sometimes wear shiny suits.What do these do? Wrap a container ofhot water with aluminium foil. The foil‘suit’ should increase the rate of cooling.How do animals keep warm? Use fake furas an insulator. Does fur still work when itis wet? Some children may havenoticed that animal fur coatsgrow thicker in the winter.Which box is best tokeep a take-away pizzahot? A variety of boxes,lined and unlined, can becompared.

More things to investigate

Do after-shave or perfume really make theskin cold? Remove the temperature probefrom the after-shave to allow evaporationto begin.If you got wet in the rain, would your wetclothes really make you colder? Study theeffect of a cool wind on the temperature ina wet glove or sock. Then cover the itemwith a polythene bag.

How can we keep warm?


When it is cold we wear extra clothing. Which would keep uswarmer: one thick jumper or two thin shirts?In this activity you will compare different clothingto keep warm with.

How can we keep warm?

1. Does clothing help to keepthe heat in?

2. What should you wear tokeep warm?

3. If you wore T-shirts and ajumper what would this do?

4. How can we make our homewarmer?

Apply:

Now find the answer to thisquestion:

· What would be best to wear inhot weather?

Temperature sensor

You need:

Hot water, container,wool, cotton,elastic bands.Computer,printer andtemperature sensor. Care!You will be using hot water. Makesure it does not get knocked over.

Investigate:


2. Wrap a container with wool and fillit with hot water. The containercan be you!

3. Get the computer to draw a timegraph.


See if 2 shirts can keep you warm:5. Wrap a container with cotton

fabric and fill it with hot water.6. Take the temperature. Make sure

the temperature is the samebefore continuing.

7. Get the computer to draw anothertime graph.

8. Stop the recording after fifteenminutes. Print the graph.

Computer

Interface Sensor

Teachers notes


Section

3Examples

38

Hot things cool because they lose heatto their surroundings. We can help themto cool bymaking thesurroundingscooler (byblowing) orby conductionthrough aspoon. Thegreater thedifference intemperaturebetween anobject and itssurroundings, thefaster it will cool.

Requirements

A plastic cup. Safety note: use hand hot water,place the cup in a tray. Temperature sensor,interface, computer cable, software.


Ask the group what they do if they aregiven a very hot drink. Do they wait or canthey cool the drink down?

Investigate

Water should be at a safe temperature.The first activity simply involves allowing acup of water to cool. The second involvestrying to speed up the cooling. Childrenmight try blowing on the surface, placingthe cup in the draught of a fan, placing itnear a window on a cold day orplacing the cup in adish of cold water.

To help compare the time graphs, ensurethe starting temperatures are similar andrecord for the same amount of time - 15minutes should be adequate.


Printedgraphs shouldbe obtainedand placedover eachother.

Apply: more to do

A spoon left in a drink will help cool it byconducting the heat into thesurroundings. A lid on a container willhelp prevent convection and conduction.If we pour a drink between two cups weprovide a bigger area for the drink to loseheat from.

More ideas to investigate

Does ice melt slower when wrapped upwith a sweater / placed in a vacuum flask?The vacuum flask will need to allow thetemperature probe to monitor thetemperature. Heat eventually finds its wayto the ice by conduction through the flask.

Making your hot drink cool

40

50

60

70

80

90

40

50

60

70

80

90


1. What was the temperatureof your freshly made drink?

2. What was its temperatureafter fifteen minutes?

3. Where do you think the heatin your drink went to?

4. What did you do to make thesecond drink cool downfaster?

5. What was its temperatureafter fifteen minutes?

Apply

See if your drink cools downfaster or slower when you:

· Leave a spoon in the drink.· Place a lid on the drink.· Pour the drink between two

cups.What is the temperature of a

hot drink that is just readyfor drinking?

Temperature sensor

Making your hot drink cool

In this activity you will measure thetemperature of a hot drink as itcools down. You will use thecomputer to help you do this.Later you can try to make the drinkcool down faster.

You need

A cup, hot water. Computer, printerand the temperature sensor. Care!You will be using hot water. Makesure it does not get knocked over.

Computer

Interface Sensor

Investigate


2. Make a hot drink. Take and recordits temperature.

3. Get the computer to draw a timegraph as it cools down.


Now see if you can speed up thecooling:

5. Make another hot drink. Take itstemperature. Make sure it is thesame temperature as your firstdrink was.

6. Get the computer to draw anothertime graph as it cools down. Try tomake your new drink cool downfaster by blowing on it.

7. Stop the recording after fifteenminutes. Print the graph.

Teachers notes


Section

3Examples

40

Sounds originate from the vibration ofsome material which set up vibrations inthe air. These air vibrations are little‘puffs’ of higher air pressure followed bygaps of lower air pressure. The loudnessor quietness of a sound is the size of these‘puffs’ or in other words, the amplitude ofthese vibrations.Loudness is measured with asound meter or soundsensor. The unit formeasuring sound is thedecibel, named afterAlexander Graham Bellthe inventor of thetelephone. A ‘Bel’ is too large a unit foreveryday use so the decibel is morecommonly used.The pitch of a sound, which is how highor low a sound is, must not be confusedwith loudness. To measure the pitch of asound you need an oscilloscope orfrequency meter.

Requirements

Musical instruments, a ticking clock,elastic bands, spoons, scissors, tuningforks, containers filled with rice or paperclips, blocks of wood, a drum, a radio andso on. Aim for a balance of percussion,string, wind and electronic sound makers.interface, cable, Sound sensor, software.


Ask about being asked to ‘turn the noisedown’ by an adult. Can adults andchildren agree on how loud is loud? Isanyone right? Does it depend on what thesound is?Explain that they will be testing varioussound makers to find out which are theloudest and the quietest. Ask how they willagree on what is a loud and what is a quietsound? They might rate the sound levelon a scale of 1 to 5, 5 being loudest.

Investigate

Get the software to show a bar gauge‘picture’ of how loud sounds are. Measurehow quiet the group can be. Show thesound level in decibels.Two points are worthconsidering:The sensor is verysensitive and picks upmost sounds in theroom. How can theybe sure they aremeasuring the soundfrom the sound makerand not somethingelse in the room?Where should thesound source andsensor be placed?Experiment to find abest position.


How do the estimates of loudnesscompare with the Sound sensor?Estimates of the loudness of a sound cancontrast wildly with the sensor. Sudden,shrill or piercing sounds appear loud eventhough they may not be. Is this whatadults object to? The importance of usingmeasuring instruments rather than aguesswork is a key idea here.

Apply: more to do

Do the shapes of ears help us to hearbetter? Place the sound sensor at one endof a tube and make a sound at the other.Try again with a paper funnel or modelanimal ears. Try using a model satellitedish - place the sensor at the centre of anopened umbrella lined with metal foil.

Can you trust your ears?


Which sound makers make theloudest sounds?Can you trust your ears todecide? Can you measure thesound level?In this activity you will usethe computer to measurehow loud sounds are.

You need

Sound makers. Computer andthe sound sensor.

Computer

Interface Sensor

Investigate

1. Which sounds will you test? Willyou play the sound makers ‘hard’or ‘soft’?

2. Try the sound makers and decidewhich sounds are quiet and whichones are loud.

3. Decide how you will record yourfindings.

4. Test each sound using the soundsensor.

5. Record each Sound level in yourtable.

Type of sound How sound ismade Quiet or Loud Sound level

Drum

Flute

Guitar

Talking

Ticking clock

1. Did you and the others agree onwhat was ‘loud’ and ‘quiet’?

2. How far away was the soundmaker from the Sound sensor?

3. Sort the sound makers intoorder, loudest first

4. What sound level would you sayis loud?

5. Make a sound level scale withthe numbers from 0 to 100.Mark it to show Quiet, Loud, andVery loud.

6. Do your ears and the soundsensor disagree?

Apply

Use the sound sensor to find whohas the noisiest shoes.If you drop something, does itmake more noise if you drop itfrom higher up?Does the shape of your ears helpyou to hear better?

Sound sensor

Can you trust your ears?

Teachers notes


Section

3Examples

42


Ask the group howthe sound from nextdoor gets to theirears. Is it throughthe air? If all the airin the classroom wasreplaced with watercould they still hear? Has anyone heardsounds underwater? Can sea creaturessuch as whales and dolphins hearunderwater? Can we hear through walls?Does anyone know of a way to hear thingsthrough a wall?

Investigate

Ask the group what they might test to findif sound can travel through them. Will thetests be affected by the noise in the room?Two levels are recorded - to compensatefor the background noise. This idea maywell confuse and is worth going over first.


Sound is carried through solids andliquids - it travels faster through solidsand liquids. The particles that make upsolids and liquidsare more closelypacked togetherthan in air so thereare more particles for soundto travel through.The fact that sound travelsthrough solids and liquids can be useful orannoying. Prisoners in jail cancommunicate by tapping on pipes;trapped miners can tap on the walls in amine to help us find them. We can hearthe dentist drilling our teeth, the noisefrom a washing machine, from traffic or abuilding works; sea divers can talk bytouching their helmets and doctors canhear and see an unborn baby womb usingsound.

What can sound travel through?

Sound needs a medium to travelthrough. The medium can be a solid suchas wood, liquids such as water or gasessuch as air. Sound travels because sound

vibrations cause solids, liquidsand gases to vibrate and carrythe sound. Sound travels fasterthrough solids andliquids than it doesthrough air. Thespeed of sound in

air is 330 metres per second, in waterit is 1400 metres per second. This is whywhales can communicate with each otherquickly even when they are miles apart.Sound does not travel through space or avacuum. Astronauts have to talk to eachother using radio. They would also heareach other if their helmets were touching,the vibrations are carried through theirhelmets.

Requirements

A ticking clock, doorbell or electric buzzer.A tank or bowl of water, glass (a window),wood (a broom ), metal (furniture), plasticpipe, a wall, a door, a string telephone.Sound sensor, interface and software. TheSound sensor is electrically safe but do notput it in water.

Computer

Interface Sensor


Can sound travel through theair? Or water, wood and metal?In this activity you will use thesound sensor to find out whatsound can travel through.

Material Sound level(touching)

Sound level(not touching)

Difference insound level

Wood

Metal

Water baloon

Plastic

String

What can sound travel through?

1. List the things that you foundsound can travel through.2. Does sound travel betterthrough wood or air?3. Give an example of where soundtravelling through metal is useful.4. Give an example of where soundtravelling through water is useful.

Apply

Does sound travel through string?Make a string telephone to findout.Who can make the best stringtelephone? Use the sound sensorto test your telephones.Do sounds get weaker withdistance?

Investigate

1. Choose a sound maker. It mustmake a sound that the soundsensor can hear.

2. Can sound travel through a door?Place the clock on the door. Pressyour ear against the door andlisten.

3. Move the clock away from thedoor. You should no longer hearthe clock through the door.

4. Place the clock on the door again.Press the Sound sensor againstthe door and record the soundreading.

5. Move the clock away from thedoor. Record the sound reading.

6. Find out if sound can travelthrough other things.

You need

Glass, wood, metal and plastic pipe; a wall, a door, astring telephone. Computer and the sound sensor.Keep the computer away from water and wet hands.

Sound sensor

Teachers notes


Section

3Examples

44

Sound proofing a building is extremelydifficult. This is because all sorts ofmaterials in the home vibrate and transmitthe sound. Having plenty of soundabsorbers, such as carpets, curtains andsoft furnishings in a room help to absorbsound. When a sound is made thevibrations in the air cause surfaces tovibrate and to reflect sound. Materialssuch as insulating felt and foam do notvibrate very well nor do they reflect soundwell. In contrast a sheet of metal or wooddoes vibrate well and does not insulatesound well.

Requirements

A consistent sound source such as abuzzer or bell. Sound proofing material:cotton wool, foam, cork, newspapers, card,wood, polystyrene, an inflated balloon, acushion, a blanket, thick or paddedclothing; cardboard egg-boxes.Computer, monitor, Sound sensor,interface, cable and software.

Computer

Interface Sensor


What is sound for? Ask the group toconsider how sound is useful. Getexamples of useful sounds: speech(communicating); music (comforting,enjoyable, exciting). Sounds warn usabout danger or danger to come. Usefulsound is aboutcommunicating. Isan old noisy cartrying to ‘tell us’something?When is soundcalled music?When is soundcalled noise?Noise is soundbeing a nuisanceor causing eardamage.

Investigate

Ask the group how they shut out soundwhen there’s a lot of noise next door?Would closing the window or the curtainshelp?Use a buzzer or bell to make a steadysound. Measure its sound level with thesensor covered with different materials inturn. Different thicknesses and mixedlayers of say, foam and polystyrene shouldalso be tested.Alternatively, place the sound sensor in a‘shoe box’ to represent a room and linethe box with various materials.


Good sound proofing depends on thematerial used. Sound insulation usuallyinvolves thick air-containing materials,such as felt.Sound can ‘leak’ around a soundinsulator.

What's the best way to stop sounds?


sounds?Sometimes sound is a nuisance.Sound from traffic and theroom next door can stop usgetting to sleep. Sound can alsodistract us from what we aredoing.How can we stop sounds? Tofind out you will use the soundsensor to find the best way tostop sounds.

MaterialSound level

(before)Sound level

(after)Difference insound level

Blanket

Folded blanket

Egg boxes

4. Put the material around thesound sensor.

5. Make a sound, measure thesound level.

6. Try the other materials.Record your results.

7. Fold the blanket to make itthicker and try again.

1. Which material is the best atstopping sound?2. Which material is useless atstopping sound?3. Does twice the thickness ofthe material stop the soundsany better?4. Do the sound proofers haveanything in common?5. How would you sound proofyour room at home?

Sound sensor

What's the best way to stop

You need

A sound maker. Materials to stopsound such as clothing, a blanket, acushion, egg boxes, cork,polystyrene. Computer and the soundsensor.

Investigate

1. Decide which sound maker you willuse. It needs to make a fairly loudsteady, sound.

2. Make a sound and measure thesound level. Record your result.

3. Choose a material that might stopsound, for example use a blanket.

Teachers notes


Section

3Examples

46

Light is produced as a result ofsomething which is hot or burning.Tungsten lighting - from atorch or domestic lamp is theresult of electricityheating a tungstenwire to its glowingpoint. Candle light isthe result of burningchemicals.Light is a form ofenergy and, in theseexamples, one form ofenergy changes intoanother. Candle light comes fromchemical energy. In the tungsten lampelectrical energy gets converted to lightenergy.

Requirements

A candle, some torches, a torch without areflector, tungsten lamp, fluorescent striplight and daylight. Light sensor, interface,cable, software. Computer and monitor.


Ask the group to list as many ways as theycan of getting light. Try to put them inorder of brightness: a torch can seemquite bright - is this brighter than thesun? Which is the brightest, the lighting inthe room or the sun outside?The business of science involvesmeasuring how bright things are ratherthan guessing. Show how it can be used togive reliable readings of light levels. It usesa scale of zero to 100.Where should the light sensor be placedin relation to the light source when takingreadings?

Investigate

Use the light sensor at a metre, or alwaysat the same distance from the source.Stray light will affect the readingsobtained. To avoid this, place a tube madeof card or foil around the sensor.


Sunlight is the brightest and candlelight isthe weakest. Fluorescent strip light ismuch brighter than tungsten light andboth are suitable for reading at nightOther factors can be taken into account -such as the warm colour of tungsten lightcompared to fluorescent light,safety and convenience.Use the electricity tariff towork out how much it wouldcost to provide say, 10 hoursof tungsten light andfluorescent light. The pricedepends on the wattage ofthe bulb, but typicallytungsten bulbs need to have awattage 3 times as high toproduce anywhere near the brightness offluorescent lights. Estimate how many setsof batteries would be needed to obtain 10hours lighting and how much this wouldcost. Finally, find out the burning timeand cost of a candle.

Apply: more to do

Does light come from the back and sidesof a light source? Place a candle in themiddle of a circle and take readings atintervals around it. Light spreads out inall directions from a light source. This iswhy we have to use reflectors and lampshades.

Which light is the brightest?


Light Source Light level

Torch

Strip light

Sunlight

Tungsten light

Candle

1. Put the lights you tested intoorder.

2. Which light would be thebest for reading in the daytime?

3. Which light would be thebest for reading at nighttime?

4. Which light costs the leastmoney to use?

5. Find out: which lights are themost costly to run?

Apply

Does light come from the backand the sides of the candle?Does light come from the backand the sides of the otherlights?

Light sensor

Which light is the brightest?

You need light to see things. Howmany ways of getting light can youthink of? Which way of gettinglight would give you the most light?The light sensor can measure howbright the light is. In this activityyou will use it to test differentlight sources to find which is thebrightest.

You need

A candle, some torches, a torchwithout a reflector, tungsten lamp,fluorescent strip light and daylight.Computer and the Light sensor.

Investigate

1. Should you hold the light sensorvery close to the lights? Shouldyou hold the light sensor far awayfrom them?

3. Can you stop light in the roomfrom getting to the light sensor?

4. Get the computer to measure thelight level.

5. Test each of the light sources.6. Record your light level readings in

a table.

Computer

Interface Sensor

Teachers notes


Section

3Examples

48

Most substances reflect some light andthat is why we can see them. White light isa mixture of many colours mixedtogether. When white light shines on say,a blue fabric, the fabric reflects blue andabsorbs every colour except blue. Similarlya red fabric reflects red and absorbs allother colours.Fluorescent fabrics, often worn by cyclists,temporarily store and emit the lightshining on them.

Requirements

Fabrics of different colour, foil, otherreflective materials, shiny and dull fabricsin the same colour. A desk lamp, lightsensor, interface, cable, software.


Discuss the road safety aspects of walkingand cycling in the evening. Many accidentshappen at this time. What can we doabout this? If wearing bright clothes is ananswer, what colour clothes are the mostnoticeable?

Can we compare the colours of clothes byeye? Is there anything we can use to helpus make a good comparison? Introducethe light sensor for measuring the lightreflected from clothes.Ask the group to consider how they willtest the fabrics. Will they need to shine alight on the fabrics? Will they press thelight sensor against them or hold it awayfrom them? How can they make theirinvestigation into a fair test?

Investigate

A light source such as a desk lamp orstrong torch can be used to illuminate thefabrics. The sensor should be directed ator be very close to each fabric tested.Ideally the Light sensor should beclamped into a fixed position.


A black fabric absorbs all the colours ofwhite light and reflects little light back. Awhite fabric absorbs little white light andreflects most colours back.Shiny and fluorescent fabrics reflect evenmore light back and are likely to be evenbetter choices for a cyclist.

Apply: more to do

Children can use their skills to findwhether fabrics look as bright in theevening. They should test their fabricsunder poor lighting conditions. Theresults table should be extended by onecolumn for this second set of results. Theymay well find some fabrics change theirposition in the 'league table'. For example,a shiny fabric will not reflect much lightunder poor lighting.

What colour should a cyclist wear?


Cyclists need to be seen. Whatcolour do you think the cyclist shouldwear? The light sensor can measure thebrightness of fabrics. In this activityyou will test coloured clothing. Can youuse the light sensor to help you choose thebest one?

You need:

Fabrics of different colour, foil, shiny anddull fabrics in the same colour. Computer andthe Light sensor.

Fabric Light level

Black

Yellow cotton

Yellow plastic

Day-Glo plastic

White

Investigate

1. How will you test the fabrics? Willyou shine a light on the fabrics totest them? Will you press thelight sensor on the fabrics to testthem? Will you just point thesensor at the fabrics to testthem?


3. Test each of the fabrics.4. Record your readings in a table.

Light sensor

Computer

Interface Sensor

1. Put the fabrics into order- put the brightest first.

2. Which fabrics would besafest to wear?

3. Can you say why somefabrics appear to bebetter?

4. Describe how you made afair test of the fabrics.

Apply

Suppose you were riding acycle in the evening. Do youthink your clothes would lookas bright? Test all yourfabrics again in dim light.

What colour should a cyclist wear?

Teachers notes


Section

3Examples

50

The light sensor works a bit like theeye. Light enters the eye in much the sameway as it enters the Light sensor. In theeye the light is focused and absorbed bythe retina. Here nerve cells respond tolight and then transmit electrical impulsesto the brain. The brain interprets thesignal as light.In the light sensor are devices that focusand respond to light. When the sensorresponds it sends an electrical messagealong the wire to the computer. Thecomputer interprets the signal anddisplays it in a variety of ways.

Glass is a good material for a windowpane. Glass has little affect effect on thepassage of light so we call it transparent (orclear). Materials, such as obscured andground glass, also reflect andabsorb very little light.They break up theimage passingthrough them andwe call themtranslucent. Materials whichabsorb or reflect all the lightreaching them are called opaque.

Requirements

Polythene, wood, card, foil, light source,thin paper (or fabrics) in a spectrum ofcolours; black polythene. Glass or plastic:clear and obscured types. (Wrap tapearound the edges of glass.) Light sensor,interface, computer cable, software.Computer and monitor.


Talk about curtains and blinds at home:are there places where they need anopaque blind that cuts out all the light?Are there other places where a blind whichlets light through and just stops peopleseeing through would be better?

Examine the materials you collectedtogether. Which would be suitable for ablind? What are their reasons? Can a lightsensor help make the choice?

Investigate

Stray light will affect the readingsobtained, so place a short paper tube overthe end of the sensor. The lightsensor will now have anarrower range ofview.In the absence ofsunlight, use adesk lamp orspot light.


From their results, they will be able tomake their choice of material for twokinds of window blind a) the opaque kindneeded to stop the morning light oruseful for a photographer’s darkroom b)the translucent kind that would be usefulin a bathroom.Most materials can be described astransparent, translucent or opaque.

Apply: more to do

Do some colours let less light throughthan others?A dark coloured material absorbs more ofthe light trying to pass through it than alight coloured material.

Stopping light from a window


You often need to stop the lightgetting into a room. What wouldyou use to do this? If you chosecurtains would you use thickfabric or thin fabric? Would thecolour make any difference?The light sensor can measure howmuch light can pass throughfabrics. In this activity you willtest some fabrics.

You need:

Polythene, wood, card, foil, lightsource, thin paper (or fabrics) indifferent colours; black polythene.Glass: clear and translucent.Computer and the Light sensor.

Investigate


2. Use the light sensor to see if glasslets light through it.

3. Can you find a way to stop lightfrom the room reaching the lightsensor?

4. Test your materials.5. Record your readings in a table.

1. Put the materials into order.2. Which material is the best

for stopping light?3. Is thick material or thin

material best for stoppinglight?

4. Which material would youuse as a window blind?

5. Which material would bebest for a bathroomwindow?

New words: transparent,opaque, translucent.

Apply

Do some colours let less lightthrough than others?

Light sensor

Material Light level

Polythene

Thin paper

Thin fabric

Translucent glass

Clear glass

Stopping light from a window

Computer

Interface Sensor

Exploring science with sensors


Section

4Investigate

52

A catalogue of explorations

The use of a computer andsensors can short cut many ofthe steps in exploring orinvestigating science. Forexample, sensors allow pupils tothink more about theirexperiment than the business ofrecording. And the 'real-time'display gives them valuablefeedback on their work.

This section catalogues anumber of opportunities formore open-ended tasks.

Temperature sensors



Section

4Investigate

53

Temperature sensors



Section

4Investigate

54

Temperature and light sensors



Section

4Investigate

55

Temperature, light and timing sensors



Section

4Investigate

56

Temperature, pressure and humidity sensors



Section

4Investigate

57

Temperature and light sensors



Section

4Investigate

58

Light sensor



Section

4Investigate

59

Sound sensor



Section

4Investigate

60

Sound sensor



Section

4Investigate

61

Timing sensors


Section

5Control

62

ControlWhy control?

Control technology involves the study ofautomated systems in a world

increasingly driven by technology.In control technology activities, childrenidentify a need and create a solution to fulfilit. Through this they will analyse situations,form hypotheses, make predictions andevaluate their work.But computer control activities can also bethe focus of many new, absorbing andpractical experiences for children. In thecourse of this, children will learn aboutautomation, sequencing computerinstructions and about the logic of controlsystems.Control is interesting to both science andtechnology curriculum areas - althoughclearly the balance, and the benefits, are infavour of technology.

See also:

Control (homeostasis) Page 17


Section

5Control

63

Control glossary

Digital sensor - a sensor or switch whichhas two states, on or off.

Light switch - a digital light sensor whichresponds to something covering it.This might be used to sense when duskoccurs and then turn on a light. Itmight also be used to sense objects ona supermarket conveyor belt.

Push Switch - a switch that responds tomomentary pressure. Use as a bellpush or to control a pelican crossing.

Toggle switch - a two-position switch likethe switch used to turn on a television.A type of digital sensor.

Pressure mat - a switch that responds tomomentary pressure. Put under a matfor a shop or burglar alarm.

Proximity switch - a switch thatresponds when close to another object.One brand of proximity switch is areed switch which is triggered whenbrought close to a magnet.

Control box - an interface (or 'Bufferbox') which allows you to switch andpower lights, motors and buzzers. Thebox will have inputs for digital sensors- and may take analogue sensors.

Barnet Box - virtually the same as aDeltronics Box or TTS box. A brand ofcontrol box with 8 output and 8 digitalinput sockets.

Smart Box - a brand of control box withoutputs, digital and analogue sockets.

Lego Interface A/B - a brand of controlbox. Lego have replaced their‘Interface A’ with the 'B' control boxthat provides analogue sensing.

Control module - an alternative to acontrol box and part of the FirstControl system. There are severalmodules to extend children'sexperience of output devices.

User Port - a socket on a computer or aninterface where you can connectcontrol boxes.

Serial Port - a computer socket whereyou connect a control box or otherinterface.

Control software - the programs used toread information from sensors andswitch devices on and off.

Control language - each controlprogram has its own language. Youuse this language to write programsfor control systems.


Section

5Control

64

Choosing control kit

For control technology work, you'll need threeingredients. You’ll need models and devices to control.

Secondly, you’ll need a computer interface to connectthem to the computer. Thirdly you’ll need software to givecommands with.The models and devices can be built from 'junk' or pukakit. Systems such as Plawco and Lego or the sophisticatedFirst Control mains module. While you will have your owncriteria for selecting from the range, consider using amixture of them.The interface should allow the easy and reliable connectionof sensors, motors and other devices. You’ll appreciate atidy integration of sensors and output devices - allowingyou to measure, for example, the temperature and thencontrol a fan.Your choice of software is tied to the interface you use asmost software is written to work with its correspondinginterface. You will want a control language which is as closeto normal English as possible. The software should avoidthe use of obscure punctuation marks in commands, e.g.Switchon [1 2] or Repeat 3 [Switchon [1 2] Switchoff [1 2]]. That kind of software is well past its 'sell by date'. Thesoftware could provide a menu of commands and offerhelpful messages if a command is entered incorrectly.Many control programs have tied themselves to the LOGOlanguage. An advantage of this approach is that it enableschildren to progress painlessly from turtle robots andLOGO into control work. The idea is a valid one but thedisadvantage is that it hasn’t made control as easy as itshould be. LOGO is fine but when combined with theclutter of a control kit things start to get difficult. It feelslike a lead weight hanging off you. My preference is for theeasiest software available - avoiding LOGO - hoping that,one day, LOGO itself will become easier. Instead look forsomething which is easy - it will not require muchcapability to achieve most 'science' purposes.

Starting out with control

Children need to develop a familiarity with the school’scomputer control kit. As their familiarity develops we

hope that they will see the kit as a tool they can use fortheir own purposes. The following examples show some ofthe possibilities in science contexts.Computer control activities can find a place in sciencetopics - particularly when children design methods ofmeasuring and controlling.


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In a weather topic devices can be made which measurewind speed or collect rain water. They may develop adevice, say a solar ‘panel’ which can turn to face the sun. In a living things topic children can make deviceswhich monitor birds arriving at a bird table. They can testwhich bird food is preferred, they may even devise amachine to meter out bird food. In an ourselves topic they may use sensors andcontrol equipment to mimic the control systems of thehuman body - such as moving in response to sound andlight. They may show how a hospital baby incubator can bekept at a steady temperature - by using a fan and/or heater. In a machines theme they can develop numeroussystems using lights, motors, drive belts, levers and gears.This could be a buggy, a washing machine, a bridge thatopens and closes, a pelican crossing or a car park barrier. In an electricity or electronics topic they can extendtheir knowledge of circuits as they wire up systems e.g.traffic lights and thermostatic control.

About the control activity sheets

In the following sheets there are problems, questionsand solutions. They start 'from scratch' and they

exemplify writing control programs using a typical controllanguage. When some familiarity with the equipmentdevelops, the detail can be cut out. For example, you mightcopy only the top half of the sheets - and use them asproblem cards.

Ideas for Control


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Automatic porch light

You want a light to come on atyour front door whenever it isdark and switch off when it getslight.

Questions

What will you use as a light?What will you use to detect whether itis day or night?At what light level will the light switchon? Above 60? Above 40? Test it tofind out.At what light level will the light switchoff? Below 60? Below 40?

Solution Use a 12v car lamp as a light. Power itusing a power pack and connect a relay toyour Control box output. Alternatively,dispense with the relay and connect alamp directly to your Control box. Connect a light sensor and the Controlbox to the sensor interface. Use a lightsensor to find out whether it is day ornight. A test with the sensor will find themost suitable on/off light level.

Apply your skills

Welcome Home: Your automatic light iswasting electricity! You want a light tocome on at your front door when youarrive home at night. Obviously it doesn’tcome on during the day.

Using a control languageWhen you have finished setting up, yourcontrol language program might be typedin like this.Type the following:

REPEAT ENTER

IF LIGHT IS ABOVE 50 THEN SWITCH ON 1 ENTER

IF LIGHT IS BELOW 50 THEN SWITCH OFF 1 ENTER

AGAIN ENTER

Test the porch light system. Repeat all

this, but build a procedure called porch:

BUILD porch ENTER

REPEAT ENTER

IF LIGHT IS ABOVE 50 THEN SWITCH ON 1 ENTER

IF LIGHT IS BELOW 50 THEN SWITCH OFF 1 ENTER

AGAIN ENTER

END

To run this procedure type:

DO porch ENTER


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Make a bath water testerwhich tells you if the bathtemperature is OK, too hot ortoo cold.

Questions

What temperature is your ideal bath?What can you use as a warning if thewater is too hot?What can tell you if the water is toocold?What can tell you if the water is OK?

Bath water tester

Solution Use 3 painted lamps and connect themto outputs 1,2 and 3 on your Control box.Some control boxes have built-in colouredLEDs. Connect a temperature sensor and theControl box to the sensor interface. A temperature of around 50 degreesmight be suitable for a bath. A red lightcould be used to show that thetemperature is too hot. Use yellow forcold, and green for just right. If the temperature is above 55 degreesthe red light should be switched on. If thetemperature is below 45 degrees theyellow light should be switched on. If thetemperature is above 45 degrees andbelow 55 degrees the green light shouldbe switched on. Remember that each lightneeds to be switched off - otherwise theremay be two or more lights on at the sametime.

Apply your skills

Bath time. Improve your bath tester sothat it also tells you when the bath is full.You might use a light sensor to detectthis.

Using a control languageWhen you have finished setting up, yourcontrol language program might be typedin like this.Type a procedure which we'll call bath:

BUILD bath ENTER

REPEAT ENTER

SWITCH OFF 1 2 3 ENTER

IF TEMPERATURE IS ABOVE 55 THEN

SWITCH ON 1 ENTER

IF TEMPERATURE IS BELOW 45 THEN

SWITCH ON 2 ENTER

IF TEMPERATURE IS ABOVE 45 AND

TEMPERATURE IS BELOW 55 THEN

SWITCH ON 3 ENTER

AGAIN ENTER

END

To run this procedure type:

DO bath ENTER


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Make an alarm clock which switches onat dawn and switches off when youshout at it.

Questions

How will the computer know that itis morning?How will the computer detect that you haveshouted at it?How loud do you need to shout to stop the alarm?What can you use to set the alarm when you go to bed?How could you tell if the alarm has been set?

Sound controlled alarm

Using a control languageWhen you have finished setting up, yourcontrol language program might be typedin like this.Type a procedure we'll call alarm

BUILD alarm ENTER

REPEAT FOREVER ENTER

WHEN INPUT 1 IS ON THEN

SWITCH ON 3 ENTER

WHEN LIGHT IS ABOVE 40 THEN

SWITCH ON 6 ENTER

WHEN SOUND IS ABOVE 80 THEN

SWITCH OFF 6 ENTER

SWITCH OFF 3 ENTER

AGAIN ENTER

END

To make this procedure run type:

DO alarm ENTER

Solution Connect a sound sensor, a light sensorsand the Control box to the sensorinterface. When the light reaches a certain levelthe alarm should be switched on. Whenthe shout achieves a certain level the alarmshould be switched off. The level at whichthis happens should be set high enoughso that it is not switched off by the alarmitself. Use a push switch to set the alarm -you might also use a green light toindicate it is set. When the push button is pressed thegreen light shows that the light sensor iswaiting for the light level to reach a certainvalue. When it does, the buzzer soundsand the sound sensor waits for the shout.The buzzer is then switched off and thewhole cycle can begin again.

Apply your skills

Turn it down ! Make an alarm which tellsyou when you’re playing your music tooloud.


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It is a hot day and thetemperature in the room isrising. Make a cooling fanwhich only works when itgets too hot.

Questions

What temperature would yousay is “too hot”?What can you use to sense thetemperature?How will you test if the temperature is too hot?What should happen if the temperature is too hot?What will you do when the fan cools the room to the temperature you want?

Cooling Fan

Solution

Connect a temperature sensor and theControl box to the sensor interface.Connect a motor and vane (fan) to theControl box. A temperature of 25 degrees might beconsidered too hot. Use the temperaturesensor to measure the temperature. Testthe temperature using the ‘IFTEMPERATURE IS ABOVE ...’command. If the temperature is too hotswitch on the ‘fan’. When the temperaturedrops, switch off the fan.

Apply your skills

Keep Warm! Make a system you can usefor keeping warm. A fan heater or hair-dryer might be used as a heater.

Using a control languageEnsure that the set-up can blow air overthe tip of the temperature probe. If theweather is cool have a hair-dryer nearby towarm the probe. The fan will start andstop when the temperature rises above 25degrees or falls below 25 degrees.When you have finished setting up, yourcontrol language program might bewritten like this.

Type in this procedure we'll call coolme

BUILD coolme ENTER

REPEAT ENTER

IF TEMPERATURE IS ABOVE 25 THEN

SWITCH ON 1 ENTER

IF TEMPERATURE IS BELOW 25 THEN

SWITCH OFF 1 ENTER

AGAIN ENTER

END

To run the procedure type:

DO coolme ENTER


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How could you make anordinary electric kettle intoan automatic kettle whichkeeps your water permanentlyhot.

Questions

What can you use to sense whenthe kettle is boiling?What should happen when thekettle boils?What should happen after thekettle is switched off?

Using a control languageWhen you have finished setting up, yourcontrol language program might bewritten like this.Type in the following mini-program orprocedure which we'll call boilme:

BUILD boilme ENTER

REPEAT ENTER

IF HUMIDITY IS ABOVE 80 THEN

SWITCH OFF 1 ENTER

IF HUMIDITY IS BELOW 80 THEN

SWITCH ON 1 ENTER

AGAIN ENTER

END

To run the procedure type:

DO boilme ENTER

Solution

Connect a humidity sensor and theControl box to the sensor interface.Connect a relay, power supply and lowcurrent heater (a car accessory forexample) to the Control box. Use a humidity sensor to respond tovapour from a manually operated kettle.Test the humidity using the ‘IFHUMIDITY IS ABOVE ...’ command.Get the system to switch off when thehumidity level reaches the test value.When the humidity level falls below thetest value again switch the kettle back on.

Apply your skills

Cook it, don't burn it! Make a thermostat fora controlled oven. Use a hair dryer as aheat source and choose a suitable sensor.

Keeping a kettle on the boil


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Thermostatic Control

Solution

Baby incubators, central heating, airconditioning and greenhouses are

examples of control systems. For thisexercise we will build a model of athermostatic control system. There is atemperature sensor, a heater and a fan.When the temperature rises above acertain level the fan is switched on. Whenit falls a heater is switched on. Howsuccessfully the temperature is controlledis monitored on a graph.

The heater can be a 12v car lamp which ispowered by a relay. Alternatively, use aHair dryer or an electric kettle powered bya mains controller.The fan, or cooling device can be a desk-fan powered by a mains controller.

/continued...

How might all this equipment keep the baby cool?

Probe todetect change

Use a mains controller to power a real fan or hairdryer

Output device: Heater

Output device: Fan

ComputerInterface

Temperaturesensor


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A thermostatic control system

A solution using icon drivensoftware (examples LegoRobolab, Flowol, JuniorControl Insight, Logicator,SOFTLAB, Investigate)

Drop a Sensor on the Benchtop

Drop a Meter on the Benchtop

Drop 2 Gates on the Benchtop

Drop 2 Switches on the Benchtop

Drop a Graph on the Benchtop

Wire the boxes together as shown.

Continued

When you have built your control system onthe SoftLab 'benchtop'Hold SHIFT and click the top Gate box.Set the gate to open when thetemperature goes below 30.

Hold SHIFT and click the lower Gate box.Set the gate to open when thetemperature rises above 30.

Hold SHIFT and click the lower Switchbox. Choose switch number 2 (the fan)

Double click the Meter to open thewindow and re-position it on the screen.

Double click the Graph to open a windowthen re-position it if necessary.

Choose Run, Check & Start.


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Sensing for ages 14 +

This section illustrates the scope for usingsensors in experiments with students aged 14

to 18. You’ll find details of the science, the sensors,the apparatus and how it all fits together.The experiments were written for in-servicetraining sessions, but with a teaching use in mind.They were also written to be used with any of thehardware and software you might find in school.So whether your temperature sensor is home-made or the very latest multi-range device, youshould find something useful here.The experiments are organised by subject: Biological topics Physical topics Page 91 Chemical topics Page 107

Older systems

Modern sensors are recognized by your software - youwill not need to tell the computer which sensor isconnected. You may have some older equipment, whichalthough it is hard to use by today's standards, still canhave some good use extracted from it. You can make use of your older sensors, such as the'Blue Box' variety, by using an adaptor supplied by theinterface supplier. However, these sensors do require youto tell the computer which sensor you have connected. Ifyou forget, you'll find that the graph displays in thewrong units - for example, a pulse rate of 100 bpm mightdisplay as 0.5 volts. The actual recording is unaffected. In most systems, the sensors plug into your interfaceand then into the computer's USB or 'serial port'. Youcan still use the older systems which plug into theanalogue port using a connecting box. Mentally substituteit for the interface illustrated in the following pages.

See also:

Introducing data logging to ages 10-13 Page 33Exploring science with sensors Page 52-61Sensors & software Page 120-


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Pulse: measuring the pulse rate

The pulse sensor provides a directmeasurement of the pulse rate. Using ityou can see the rate of change in pulserate - instead of just a measurement at apoint in time.You might use it to monitor pulse ratebefore, during and after exercise.These instructions show you how to usethe sensor to obtain the kind of traceshown in the Sample graph below.

Apparatus

Pulse sensor with probe. The probe mayneed some seconds to stabilise.

Setting up

Connect the pulse sensor to a socket onthe interface.Connect the pulse probe to the body.Some systems recognize the sensors youattach automatically, in others you do thisyourself.

Recording the data

Record for 10 minutes.

Using the results

How does the graph show an increase inpulse rate?What must be happening when the graphtrace rises?How can we use this to measure the fitnessof an individual?Save your data on disk and print yourgraphs.

Sample graph

Computer

Interface

or radio link

Pulse sensor

Ear orfinger probe


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Pulse: monitoring the heart beat

The pulse sensor can show the bloodflow through the probe, i.e. you can seethe heart beat, shown in the Sample graphbelow, rather than count heat beats. Youshould be able to monitor some of thedetail of the heart cycle.You might monitor the blood flow before,during and after exercise.These instructions show you how to usethe sensor to obtain the wave trace shownbelow.

Apparatus

Pulse sensor with probe.

Setting up

Connect the pulse sensor to a socket onthe interface. How you get the pulse wavetrace varies with the equipment you have -you may need to:use a terminal marked Pulse Out on thesensor. Or use another channel on thesoftware or set a switch on the sensoritself.Connect the pulse probe to the body.The software needs to know that you wantto measure the pulse wave.

Recording the data

Record for 40 seconds.

Using the results

Count the number of peaks to work outthe pulse rate.Does the shape of the peak change afterexercise? Why does this occur?Explain the notch on the side of eachpeak.Save your data on disk and print thegraphs.

Sample graph

Computer

Interface

or radio link

Pulse sensor

Ear orfinger probe


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Arterial pulse / Sphygmograph

A sphygmomanometer cuff constrictsthe arterial blood flow through the arm.When the pressure sensor is attached tothe cuff it is possible to obtain a picture ofpressure changes as the cuff pressure isincreased and then released.

Apparatus

Sphygmomanometer cuff, pressuresensor.

Setting up

Connect the pressure sensor to a socketon the interface and connect the cuff tubeto the sensor. Attach the cuff to the upperarm.Your pressure sensor needs to be able towork within a wide range, such as from 0to 100kPa. Some systems recognize thesensors you attach automatically, in othersyou do this yourself.

Recording the data

Record for 2 minutes. If you record forlonger you will lose some of the finerdetail in the graph.

This can be worrying, so choose yoursubject carefully! Inflate the cuff until theblood flow through the arm stops.If the sensor has a zero control, use it toget the reading on the screen. Thenrelease the pressure slowly using the cuffthumb-wheel. You may be able to recordthe arterial pulse.

Using the results

Zoom in on the part of the graph showingthe arterial pulse.Explain how we normally measure theblood pressure.Save your data on disk and print thegraphs.

Computer

InterfacePressure sensor

Arm cuff


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Breathing movements

Recording the data

Do a test run, and if the sensor isadjustable you might need to adjust it toget the reading on the screen.Record for 1 minute.

Using the results

Count the number of peaks to work outthe respiration rate.Zoom in on a good part of the graph.Which part of each peak is inspiration?Does the 'expiration' part show the sameshape as this, if not why not?Do the shapes of the peaks look differentafter exercise?Does it matter where on the torso thestethograph is attached?Save your data on disk. Print the graph.

There are several ways to monitor themovements of your chest. You can getcreative with a position sensor and aspirometer box - and this works well. Oryou can use a custom device: there is abreathing (stretch) sensor and there is a'corrugated chest strap device', called astethograph, which is worn around thechest. In this example, chest movementscause (semi-quantitative) changes in airpressure which are monitored by apressure sensor.If you take readings before and after someexercise you should find some interestinggraph patterns to explain.

Apparatus

Breathing sensor such as a stethograph,plastic tubing and a pressure sensor.

Setting up

Connect the sensor to a socket on theinterface.Attach the belt around the chest. Wear itsuch that it does not restrict breathing orslip off.Some systems recognize the sensors youattach automatically, in others you do thisyourself. If you are using a pressuresensor, it needs to be set to work over anarrow range.

Computer

Interface

Pressure sensor

Chest strap


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Some software features a continuousmonitoring feature where the time axis isconstantly replotted. SoftLab, an exampleof a fairly advanced program, does thisparticularly well. As on the previouspage, breathing movements aremonitored by a device strapped aroundthe chest.

Apparatus

A breathing sensor: stethograph, plastictubing, pressure sensor and interface.

Breathing movements

Double click the Gauge to open a window;re-position it on the screen.Double click the Graph to open a window,re-position the window.Choose Data, Store to store eachrecording.Choose Run, Check & Start.

Start breathing! Data will be collecteduntil the graph is complete.To start a new run, Choose Run, Start/Stop

Results

From the graph window choose Options,Customise to alter the x-axis (time) or they-axis (breathing).Press ALT + PRINT SCREEN to capture

the graph window to theWindows clipboard. Inyour word processor,choose Edit, Paste toadd the graph to yourreport.

Using the program


Choose Pressure Sensor. Click OK.

Drop a Gauge on the Benchtop



An example using SoftLab software

Connect the sensor to thefirst socket on the interface.

Computer

Interface

Pressure sensor

Chest strap


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Enzymes: starch and amylase

Amylase catalyses the hydrolysis ofstarch. Iodine can be used as an indicatorto show that the starch has been brokendown. A light sensor can be used, like acolorimeter, to monitor this change.This experiment aims to show the effect ofdifferent temperatures on the action ofamylase.

Apparatus

Fresh amylase and starch solutions,iodine, distilled water, a sheet of blackpaper, light sensor.

Setting up

Set up the light sensor and beaker. Add20cm3 starch solution and 2-3 drops ofiodine. (Or: use a smaller volume in aplastic cuvette - use a discarded plastic pHindicator paper box).Use black paper to shield the beaker fromchanges in the light level. Try not tocompletely cover the chemicals - it helps ifyou can see the colour change.Connect the light sensor to a socket onthe interface.Start the computer recording and look fora trace on screen. If the Light sensor isadjustable, change its range to get thetrace on screen. Some systems recognizethe sensors you attach automatically, inothers you do this yourself.

Recording the data

Add 5cm3 amylase to the beaker.Record for 15 minutes.When the reaction is complete replace thebeaker and solutions. Make a newrecording, but at a different temperature.

Using the results

What happens to the appearance of thesolution during the reaction?What does the graph tell you about theprogress of the reaction?When was the reaction working at itsfastest?What condition did you change? How hasthis affected the graph?Calculate the average gradient of thegraphs. Which part of the graph shouldyou use? What does this tell you?Save your data on disk. Print the graph.

Computer

Interface

Light sensor


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This experiment studies the effect of theenzyme pepsin on protein. Pepsincatalyses the hydrolysis of the protein,albumin into amino acids. As the proteinsolution is cloudy and amino acids aresoluble the liquid changes from cloudy toclear. The light sensor can be used, like acolorimeter, to monitor this change.You can try this at different pH values.

Apparatus

Water bath, 1g/100 cm3 pepsin solution,1% fresh egg white, 0.1M hydrochloricacid HCl, 0.1M sodium carbonateNa2CO3, light sensor.

Setting up

Set up the light sensor and beakercontaining 25cm3 of egg white + 5cm3acid.Connect the light sensor to the interface.Warm the beaker in a 35°C water bath.Some systems recognize the sensors youattach automatically, in others you do thisyourself. Start the computer recordingand look for a trace on the screen. If thelight sensor is adjustable, change its rangeto get the trace on screen.

Recording the data

Remove the beaker from the water bathand place it over the light sensor. Add10cm3 pepsin solution to the beaker.Record for 25 minutes.When the reaction is complete, repeat theexperiment using 25cm3 of egg white and5 cm 3 sodium carbonate instead of the 5cm3 acid.

Using the results

What happens to the appearance of thesolution during the reaction?What does the graph tell you about theprogress of the reaction?When was the reaction fastest?What condition did you change? How hasthis affected the graph?Calculate the average gradient of thegraphs. Which part of the graph shouldyou use?Save your data on disk and print thegraph.

Enzymes: pepsin and protein

Computer

Interface

Light sensor


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Sensors can be used to monitorphotosynthesis. They can show that as thelight level increases, the oxygen level willalso increase. It is also possible to show theeffect of carbon dioxide levels (as addedhydrogen carbonate solution) and to showthe effect of coloured light.A data logger allows readings to be takenover a period of time such as over aweekend.

Apparatus

Live pond weed (keep warm andilluminated before use), flask, 10g/Lsodium hydrogen carbonate NaHCO3solution, oxygen probe, oxygen sensor,light sensor.

Setting up

Set up the oxygen sensor as shown. Switchon the sensor 15 minutes before use.Connect the oxygen sensor to the firstsocket on the interface. Connect the lightsensor to the next socket.

You may be able to calibrate the sensor toread 21% oxygen in room air. If the lightsensor is adjustable, use a Log range.Some systems recognize the sensors youattach automatically, in others you do thisyourself.

Recording the data

Record for 30 minutes.Shield the plant from light for the first 10minutes. Use ambient light for the next 15minutes. Use bright light for theremaining time.

Using the results

Is oxygen produced steadily duringphotosynthesis?How does the light level affect the rate ofphotosynthesis?Does heat from the light source affectyour experiment?How could you check that heat was notaffecting your experiment?Save your data on disk. Print the graph.

Photosynthesis - by measuring oxygen

Plant

Interface

Light sensor

Oxygen sensor

Computer


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Sensors can be used to monitorphotosynthesis. They can show that as thelight level increases, the pH will decrease.This happens because of the use of carbondioxide by the plant.It is also possible, using gelatine filters, toshow how this is effected by differentcoloured light.

Apparatus

Live pond weed (keep warm andilluminated before use), flask, pHelectrode, pH sensor, light sensor.

Setting up

Connect the pH sensor to the first socketon the interface. Connect the Light sensorto the next socket.You may be able to calibrate the pHsensor to read correctly in a known buffersolution. If the Light sensor is adjustable,use a Log range. The software needs toknow that you have connected a pHsensor and a light sensor. Some systemsdo this automatically.

Recording the data

Record for 30 minutes.Shield the plant from light for the first 10minutes. Use ambient light for the next 15minutes. Use bright light for theremaining time.

Using the results

What happens to the pH of the waterduring photosynthesis?Why does this happen?Does the pH change steadily duringphotosynthesis?How does the light level affect the rate ofphotosynthesis?Does heat from the light source affectyour experiment?In this experiment, where does the plantobtain its carbon dioxide from?Save your data on disk. Print the graph.

Photosynthesis - by measuring pH

Computer

Interface

Light sensor

pH sensor


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When living things respire they use upoxygen. This can be monitored using anoxygen sensor. The living thing can be aplant, animal or microorganism. Maggots,locusts, or yeast are often used and so canpond-weed. If you use Elodea, its containershould be kept in the dark or wrapped infoil.It is also quite easy to show howtemperature affects the rate of respiration- however, in this example, the oxygensensor should be able to compensate forits own response to temperature changes.

Apparatus

Live material in a flask, oxygen probe,oxygen sensor. Take care to avoiddamaging the membrane tip of the probe.

Setting up

Set up the oxygen probe and sensor asshown. Let the sensor stabilise for around15 minutes before use.The software needs to know that you haveconnected this sensor - which somesystems do for you. You may be able tocalibrate the sensor to read 21% oxygen inroom air.

Recording the data

Record for 60 minutes. Experience willgive the most appropriate time for theliving material under investigation.

Using the results

How does the oxygen level change duringthe experiment?What does the graph tell you aboutrespiration?If you recorded for twice as long howwould the graph look?How would temperature affect yourgraph?

Respiration

Computer

Interface

Oxygen sensor


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84

Temperature sensors can be used tomeasure the heat produced during seedgermination. As the sensors can recordvery small changes, this experiment yieldsresults in a very short period of time.Hypochlorite solution is used to kill fungalspores. A batch of seeds, killed by boilingis used as a control.Using very similar equipment, you canmeasure the heat produced by freshly cutgrass.

Apparatus

2 vacuum flasks, cotton wool, germinatingpea seeds, hypochlorite solution, bunsenburner, mat and gauze, interface,temperature sensors.

Setting up

Connect two temperature sensors to thefirst two sockets on the interface.Soak the pea seeds, in Hypochloritesolution, for 15 minutes to kill off fungalspores. Divide the batch into two and boilone for 10 minutes to kill the seeds. Allowto cool.Set up the two vacuum flasks with thebatches of pea seeds. Put a temperatureprobe each and add a cotton wool plug.

Some systems recognize the sensors youattach automatically, in others you do thisyourself. If the sensors have a rangecontrol, use a suitable range such as -10-40 degrees.

Recording the data

Record for 30 minutes or more.

Using the results

What does the graph tell you about heatand germination?What does the shape of the graph tell youabout the progress of germination?Did the control show any temperaturechange?If you recorded for twice as long howwould the graph look?Save your data on disk. Print the graph.

Energy from germinating seeds

Computer

Temperature sensor

Temperature sensor

Boil these seeds first

Interface


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85

As food burns it releases energy. Thisenergy can be used to heat up a knownvolume of water and so calculate its energycontent. The temperature change can beeasily monitored using a temperaturesensor. Furthermore, if the food stopsburning too soon, the graph will showhow much the water cools and you canadd this temperature change into yourcalculations.

Apparatus

Clamp, stand, boiling tube, balance, food(e.g. a peanut), a mounted needle,interface, temperature sensor.

Setting up

Connect the temperature sensor to thefirst socket on the interface.Weigh the food sample and add 30 cm3water to the boiling tube.Some systems recognize the sensors youattach automatically, in others you do thisyourself. If the sensor has a range control,use a suitable range e.g. from 0-100.

Recording the data

Record for 5 minutes. Heat the food in aBunsen flame to light it. Heat the tube ofwater with the food until it has completelyburnt, relight the food if necessary.Repeat with another food.

Using the results

How does the graph tell you how muchenergy is in the food?Did your food extinguish before burning?Did the water lose heat as a result?Did you burn equal amounts of eachfood? If not, how will you compare theresults from different foods?Did the food give all of its energy to thewater?Use the software to read temperaturevalues from the graph.Save your data on disk. Print the graphs.Use a spreadsheet to help with anycalculations you need to do. (The IT inSecondary Science book shows how).

Energy in food

ComputerBurning peanut

Temperature sensor

Interface


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86

Recording the data

Add an equal quantity of sugar to eachflask.Pour a layer of oil into one flask to showanaerobic respiration.Loosely plug them with cotton wool.Record for up to 24 hours. You may getresults much sooner than this.

Using the results

How do you know that the yeast isrespiring?What do the shape of the graphs tell youabout the progress of respiration?How can you tell which flask showed themost respiratory activity?If you recorded for twice as long howwould the graph look?Save your data on disk. Print the graphs.

Aerobic & anaerobic respiration

Temperature sensors can be used tomeasure the heat produced as yeastrespires in a vacuum flask. Since thesensors can record very small changes, thisexperiment yields results in a relativelyshort period of time. A second flask can beset up to show the effect of anaerobicrespiration - in this case, the yeast iscovered with oil.

Apparatus

2 vacuum flasks, cotton wool, yeast, sugar,oil, interface, temperature sensors.

Setting up

Connect two temperature sensors tosockets 1 and 2 on the interface.Make a yeast suspension and divide itequally between two vacuum flasks.Put a temperature probe each flask.Some systems recognize the sensors youattach automatically, in others you do thisyourself. If the sensors have a rangecontrol, set a suitable range e.g. tomeasure up to 40 degrees.

Computer

InterfaceTemperature sensor

Vacu

um fl

ask

Temperature sensor

Vacu

um fl

ask


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In the manufacture of foods, such asyoghurt, bacteria turn lactose into lacticacid. The acid denatures the milk proteinand sets it solid. In the process, bacteriause oxygen and, of course lower the pH ofthe milk. Sensors can be used to monitorboth of these processes.

Apparatus

Flask, cotton wool, live yoghurt, milk,water bath, clamps and stands, interface,pH buffer solution, pH sensor, oxygenprobe, oxygen sensor.

Setting up

Place 200 cm3 milk and 10 cm3 yoghurtinto the beaker. Set the water bath to35°C. Connect the oxygen sensor tosocket 1 on the interface. Connect the pHsensor to socket 2 on the interface.Place the pH and oxygen probes in theyoghurt and milk mixture.

Some systems recognize the sensors youattach automatically, in others you do thisyourself. You may be able to calibrate theoxygen sensor to read 21% oxygen inroom air. You may be able to calibrate thepH sensor to read correctly in pH buffersolution.

Recording the data

Record for up to 10 hours.

Using the results

What does the graph tell you about thechange in pH during fermentation?Why does the pH change?What does the graph tell you about thechange in oxygen level duringfermentation?Why does the oxygen level change?How do the graphs change with respect toeach other? Is there a pattern here?Save your data on disk. Print the graph.

Fermentation

Oxygen sensor

Computer

Interface

pH sensor

Water bath


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Fermentation - long experiment

Recording the data

Place the pH and oxygen probes in theyoghurt and milk mixture.Press the button on the data logger thatstarts it recording.

Transferring the data to computer

Connect the data logger to the computer.Get the software to transfer data from it.

Using the results

What does the graph tell you about thechange in pH during fermentation?Why does the pH change?What does the graph tell you about thechange in oxygen level duringfermentation?Why does the oxygen level change?How do the graphs change with respect toeach other? Is there a pattern here?Save your data on disk. Print the graph.

Oxygen sensor

Computer

Data logger

pH sensor

Water bath

In the manufacture of foods such asyoghurt, bacteria turn lactose into lacticacid. The acid denatures the milk proteinand sets it solid. In the process, bacterialower the pH of the milk and also useoxygen. Sensors can be used to monitorboth of these processes. A data loggerallows readings to be taken over a longerperiod of time such as over the weekend.

Apparatus

Flask, cotton wool, live yoghurt, milk,water bath, clamps and stands, datalogger, pH buffer solution, pH sensor,oxygen probe and oxygen sensor.

Setting up

Place 200 cm3 milk and 10 cm3 yoghurtinto the beaker. Set the water bath to35°C. Connect the oxygen sensor tosocket 1 on the data logger. Connect thepH sensor to socket 2 on the data logger.

An example usinga data logger


Section

6Experiments

89

A pressure sensor can be used tomonitor the progress of osmosis. In thisexperiment a dialysis bag containingsucrose solution is placed in a beaker ofwater. Over a period of time, water entersthe bag and even very small changes canbe measured. Initially, the rate of osmosisis rapid, but as the concentration gradientchanges the rate of osmosis decreases.A manometer sensor can be substitutedfor the pressure sensor.

Apparatus

Sucrose solutions, Dialysis (‘Visking’)tube, connecting tube for the sensor,beaker of water for the dialysis bag,interface, pressure sensor.

Setting up

Connect the tube from the suspendeddialysis bag to the sensor.Connect the sensor to socket 1 on theinterface.Some systems recognize the sensors youattach automatically, in others you do thisyourself. If the sensor has a zero controlyou may want to use it when yourexperiment is ready to run.

Recording the data

Record for up to 1 hour. The exact timewill depend on the concentration of thesolutions.You can repeat the experiment using adifferent sucrose solution concentration

Using the results

How is a change in volume shown on yourgraph?What does the graph tell you about thechange in volume during osmosis?Why does the pressure change?What would happen if you used a moreconcentrated sucrose solution?Save your data on disk. Print the graph.

Osmosis

Computer

Interface

Dialysis tubing

Pressure sensor


Section

6Experiments

90

A position sensor can be attached to aplant to record its growth. Depending onthe plant chosen this is a very slowprocess. Using a sensor greatly decreasesthe time taken before the results can beused. It is possible to compare the effectsof light and dark and other factors onplant growth. Ideally, two plants and twoposition sensors would be used. In orderto allow a longer period of measurementthe experiment is best performed using aposition sensor attached to a data loggeras described below.

Apparatus

Clamps and stands, plant, such as agrowing bean and thread, data logger andposition sensor.

Setting up

Set up the position sensor and plant. Usethread to tie the plant to the positionsensor. If the sensor is placed the 'otherway' round, the graph will develop in theopposite direction.

Recording the data

Connect the sensor to socket 1 on thedata logger.Press the button on the data logger thatstarts it recording.

Transferring data to the computer

Connect the data logger to the computer.Get the software to transfer data from it.

Using the results

How is plant growth shown on the graph?What does the graph tell you about plantgrowth? Is it steady - or does its ratechange during the day or night?What sources of error can you see in thisexperiment?Save your data on disk. Print the graph.

Plant growth - long experimentAn example using a data logger

Computer

Data logger

Lever arm

Position sensor

Thread


Section

6Experiments

91

Recording the data

Switch on the heater. Don’t let thetemperature exceed 65°C.Record for 20 minutes.

Using the results

What does the graph tell you about thechange in temperature during theexperiment?What does the graph tell you about thechange in oxygen level during theexperiment?Why does the oxygen level change?How do the graphs change with respect toeach other? Is there a pattern here andwhat does it tell you about the solubility ofoxygen at different temperatures?With a graph on the screen, get thesoftware to plot temperature on thehorizontal axis and plot the oxygen levelon the vertical axis.Save your data on disk. Print the graph.

Oxygen solubility and temperature

As the temperature of water increases,the solubility of oxygen decreases. This issignificant in pollution studies - forexample, when factory outflow warms ariver. In this experiment a sample ofaerated water is warmed as the oxygenlevel and temperature are monitored bysensors. The software can plot the oxygenlevel against the temperature. Theresponse of the oxygen probe is itselfaffected by temperature so a thermistorcompensates for this.

Apparatus

Water, aquarium pump to aerate thewater, beaker, water bath, stirrer/heater,interface, oxygen probe / oxygen sensor,temperature sensor.

Setting up

Aerate the water with the pump. Let theoxygen sensor stabilise for around 15minutes before use.Connect the oxygen sensor to socket 1 onthe interface. Connect the temperaturesensor to socket 2 on the interface.Some systems recognize the sensors youattach automatically, in others you do thisyourself. If the temperature sensor has arange control, set this to a suitable rangeeg to measure up to 40 degrees. You maybe able to calibrate the oxygen sensor toread 21% oxygen in room air.

Computer

Interface

Oxygen sensor

Water bath

Temperature sensor


Section

6Experiments

92

The radioactivity sensor is normallyconnected to a standard Geiger-Mullertube and can produce a radioactive decaycurve in ‘real-time’. This is a veryconvincing display of radioactive decay.Protactinium, with its half life of just 72seconds, makes an ideal radioactivematerial for this experiment.

Apparatus

Geiger-Muller tube, clamp stand, sourcesuch as a Protactinium generator,interface, radioactivity sensor.Connect the GM tube to the sensor andthe sensor to socket 1 on the interface.

Setting up

Some systems recognize the sensors youattach automatically, in others you do thisyourself. If you can adjust the range onthe sensor, set it to around 50 cps.You may be able to get the software tocalculate Ln(count rate) and plot this inreal time.

Radioactive decay

1. Clamp the Geiger-Mullertube over the source - connectthis to the sensor.2. Connect the sensor to socket1 on the interface.

Computer

InterfaceGM tube


Radioactive source

Recording the data

If you are using a Protactinium generator,give it a shake and then start recording.Record for up to 10 minutes. The exacttime will depend on the source.

Using the results

How is a decrease in radioactivity shownon your graph?Does the radioactivity change steadily or isthere more to it?Use the software to calculate Ln (countrate) and plot this against time. How isthis graph different?Use the software to perform a leastsquares fit on the raw decay curve.Save your data on disk. Print the graph.


Section

6Experiments

93

Penetration by radiation

Computer

Interface


Ruler to measure distance

GM tubeRadioactive source

Recording the data

Start recording - you should be promptedto enter a distance at the keyboard. Setthe GM tube next to the source and typein 0 for the distance.Move the GM tube 5cm further away.Type in 5 for the distance. Continuemoving the tube and entering thedistance.

Using the results

How is a decreasing amount ofradioactivity shown on your graph?How does the radioactivity change withdistance?Use the software to find the relationshipbetween count rate and distance.Save your data on disk. Print the graph.

1. Clamp the Geiger-Muller tube next to thesource - connect this to the sensor.2. Connect the sensor to socket 1 on the interface.

The radioactivity sensor is normallyconnected to a standard Geiger-Mullertube and provides a measure ofradioactivity. In this investigation theintensity of a radioactive source iscompared over different distances. Theinvestigation can be extended to show theeffect of distance and penetrationthrough various materials - in fact this is aparticularly helpful demonstration.

Apparatus

Geiger-Muller tube, clamp stand,radioactive sources - alpha, beta andgamma. Metre rule, interface, radioactivitysensor. If required, paper, aluminium andlead of different thicknesses.

Setting up

Connect the GM tube to the sensor andthe sensor to socket 1 on the interface.Some systems recognize the sensors youattach automatically, in others you do thisyourself. If you can, set the range on thesensor to cover 0-50 cps. The softwarealso needs to know that you will beentering distances, of between 0 and 100cm, via the keyboard.


Section

6Experiments

94

The magnetic field sensor responds to amagnetic field. In this experiment thesensor is moved through Helmholtz coilsand the variation in field is measured.

Apparatus

Clamp stand, Helmholtz coils, leads,power supply, metre rule, interface,magnetic field sensor.

Setting up

Arrange the apparatus as shown. Connectthe Magnetic field sensor to socket 1 onthe interface.Some systems recognize the sensors youattach automatically, in others you do thisyourself. If you can, set the range on thesensor to cover 0-10 mT. The softwarealso needs to know that you will beentering distances, of between 0 and 100cm, via the keyboard.

Recording the data

Start recording - you should be promptedto enter a distance at the keyboard. Setthe probe next to the coil and type in 0 forthe distance.Move the probe 1cm into the coil. Type in1 for the distance. Continue moving theprobe and entering the distance eachtime.

Using the results

How is an increasing amount of magneticfield strength shown on your graph?How does the field strength change withdistance?Save your data on disk. Print the graph.

Magnetic fields

Computer

Interface

CoilMagnetic field sensor

Power for coil

Ruler to measure distance


Section

6Experiments

95

The magnetic field sensor responds tomagnetic fields. We can use this idea,together with a metre rule damped with asand bag, to demonstrate how aseismometer might function. If theapparatus is ‘disturbed’ a trace on thescreen can represent an ‘earthquake’event.A position sensor can be used instead ofthe magnetic field sensor, just as effectivelyhere.

Apparatus

Clamp stands, sand bag, magnet, metrerule, interface, magnetic field sensor.

Setting up

Arrange the apparatus as shown. Connectthe magnetic field sensor to the firstsocket on the interface. If you can, set therange on the sensor to cover 0-10 mT.The identity of the sensor is unimportantin this experiment.

Seismometer

Recording the data

Record for 1 minute. During this minute,disturb the apparatus to simulate anearthquake.If you record for longer you will lose thefiner detail from your recording.

Results

How is an earthquake represented onyour graph?Are you able to measure the size of anearthquake using this method?Could such a seismometer be used topredict earthquakes?Save your data on disk. Print the graph.

Computer

Interface

Sand bag


A position sensor can also be used here

Metre rule



Section

6Experiments

96

In this experiment an electrical cell istested to exhaustion. The cell might be adry-cell, an alkaline cell or a lead-acidaccumulator. The decreasing voltage ismeasured over a (long) period of time andthe software will show this as a graph ofvoltage against time.

Apparatus

1.5V dry cells, lamp, switch, leads, voltagesensor, interface.

Setting up

Connect up the circuit as shown -disconnect the battery for the moment.Connect the sensor to socket 1 on theinterface.Some systems recognise the sensors youattach automatically, in others you do thisyourself. If the voltage sensor has multipleranges, use the 2V range.

Recording the data

Connect up the battery. Record foraround 48 hours.Repeat using a different type of battery.

Using the results

How does the graph show the decay ofthe battery?How do different batteries decay withtime?What uses would you recommend foreach type of battery?Find out if temperature affects theperformance or recovery of the battery?Save your data on disk. Print the graphs.

Using a data logger

As an alternative, a data logger can beused to collect the data independently ofthe computer.1. Set up the circuit as shown. Connect thesensor to socket 1 on the data logger. Ifyou can, set the range on the sensor to2V.2. Press the button which starts the datalogger recording.3. When the cell is exhausted, get yoursoftware to transfer data from the datalogger.

Battery life

Computer

Interface or Data loggerVoltage sensorLamp

Battery under test

- +Interface


Section

6Experiments

97

The temperature, voltage & current of aheating unit are measured over a periodof time. This allows us to calculate thepower of the heater (voltage x current),and then to plot this against thetemperature. As the power increases, sodoes the temperature. Your software canproduce the graphs quite easily.

Apparatus

Heater unit (e.g. 24W), smoothed 12VDC power supply, interface, temperature,voltage and current sensors.

Setting up

Connect up the circuit as shown. Placeexactly 100 cm3 water in the beaker.Connect the current sensor to socket 1,the voltage sensor to socket 2 and thetemperature sensor to socket 3.If the sensors are adjustable, set a 2Arange on the current sensor, a 10V rangeon the voltage sensor and a 0-100 rangeon the temperature sensor. Some systemsrecognise the sensors you attachautomatically, in others you do thisyourself.You may be able to set up the software toplot the energy (V x I x time) againsttemperature as the experiment proceeds.

Heating effect of an electric current

Computer

InterfaceCurrent sensor

Heating unit

Temperature sensor

Voltage sensor

- +

- +


Section

6Experiments

98

Recording the data

Switch on the power to the heater.Record for 20 minutes.

Using the results

What does the graph tell you about thechange in temperature?What does the graph tell you about thechange in current?What does the graph tell you about thechange in potential difference?Use the software to calculate the energy(V x I x time). Try to plot energy againsttemperature.Save your data on disk.Print the graphs.

...heating effect of an electric current

Computer

InterfaceCurrent sensor

Heating unit

Temperature sensor

Voltage sensor

- +

- +


Section

6Experiments

99

The voltage & current of a thermistorare measured as its temperature changes.Sensors allow graphs of voltage andcurrent to be plotted against time. Notonly can the resistance of the thermistorcan be calculated but also the relationshipof Ln(temperature) against 1/current.

Apparatus

TH7 thermistor, smoothed power supply,heater/stirring unit, interface,temperature, voltage and current sensors.

Setting up

Connect up the circuit as shown.

Thermistor characteristics

Computer

Current sensor

Thermistor

Temperature sensor

Voltage sensor

- +

- +

Interface

Connect the current sensor to socket 1,the voltage sensor to socket 2 and thetemperature sensor to socket 3.If the sensors are adjustable, set a 1Arange on the current sensor, a 5V rangeon the voltage sensor and a 0-100 rangeon the temperature sensor. Some systemsrecognise the sensors you attachautomatically, in others you do thisyourself.You may be able to set up the software toplot the resistance (V / I) againsttemperature as the experiment proceeds.


Section

6Experiments

100

Recording the data

Heat the beaker to almost boiling andthen allow it to cool. Record for 20minutes.You may need to do a test run to establisha suitable voltage for the power supply.

Using the results

What does the graph tell you about thechange in temperature?What does the graph tell you about thechange in current?What does the graph tell you about thechange in potential difference?How does the temperature affect thecurrent and potential difference?Use the software to calculate the resistance(V / I). Try to plot resistance againsttemperature.Use the software to calculate Ln(Temperature)Use the software to calculate 1/Current.Plot this against Ln(temperature).Save your data on disk. Print the graphs.

... thermistor characteristics

Computer

Current sensor

Thermistor

Temperature sensor

Voltage sensor

- +

- +

Interface


Section

6Experiments

101

In this experiment the resistance of alamp, resistor or diode is measured as thecurrent is varied. Voltage and currentsensors make the measurements while thesoftware plots the results in real-time.After the experiment, the resistance andthe power can be plotted against thepotential difference.

Apparatus

Rheostat, dry-cells, lamp, Si / Ge diodes,resistors (e.g. 18 and 36 ohm), interface,voltage and current sensors.

Setting up

If the sensors are adjustable, set a 1Arange on the current sensor and a 2Vrange on the voltage sensor. Some systemsrecognise the sensors you attachautomatically, in others you do thisyourself.You might get the software to plot thefollowing as the experiment proceedsrather than afterwards:the current against potential difference.the resistance (V / I) against potentialdifference.the power (V x I) against potentialdifference.

Current-Voltage relationships

Recording the data

Note that you will not be recordingagainst time, just one variable againstanother.Start recording. Move the rheostat sliderto change the current in small steps. Getthe software to plot a reading at each step.If no points can be seen, your readingsmay be out of range - in fact a test run, tocheck this, is recommended anyway.

Using the results

What does the graph tell you about thechange in current?What does the graph tell you about thechange in potential difference?What is the relationship between currentand potential difference?Use the software to calculate the resistance(V / I). Try to plot resistance againstpotential difference.Use the software to calculate power (V xI). Try to plot this against potentialdifference.Save your data on disk. Print the graphs.

Computer

Voltage sensor

Rheostat

Current sensor- +

- +

Interface


Section

6Experiments

102

Current-Voltage relationships

Using the program


Choose Current Sensor . Click OK.


Choose Voltage Sensor. Click OK.

Drop 2 Meters on the Benchtop



Apparatus

Rheostat, dry-cells, lamp, Si / Ge diodes, resistors (e.g. 18 ohm), interface, voltage and currentsensors. Example using Softlab

Double click the Meters to open their windows.Re-position the windows.Double click the Graph to open a window. Re-position the window.From the Graph windows choose Options,Customise to alter the x-axis to VOLTS.Choose Data, Store to store each reading.Choose Run, Check & Start.Move the rheostat slider. A graph will beplotted.To stop recording, choose Run, Start/Stop

Results

From the graph window choose Options,Customise to alter the x-axis or the y-axis.From the graph window choose Options,Line with symbols to change the style ofthe plot from a plain line to a line withsymbols.You can then use a calculator box to workout the resistance (V / I). Wire this to aseparate graph box where the resistancecan be plotted against potentialdifference.Or you can use a calculator box to workout the power (V x I). Wire this to aseparate graph box where the power canbe plotted against potential difference.

An example using icon driven software

Computer

Voltage sensor

Rheostat

Current sensor- +

- +

Interface

Connect the current sensorto socket 1 and the voltagesensor to socket 2.Some software allows you to

plot the readings of one sensoragainst another. Examples suchas PASCO's Data Studio,LEGO's ROBOLAB do thisparticularly intuitively. As on theprevious page, the resistance of alamp, resistor or diode ismeasured as the current is varied.


Section

6Experiments

103

The voltage & current of a capacitor aremeasured as it charges and discharges.Sensors allow a graph to be plotted as thishappens. The effect of different values ofthe capacitor and resistor can easily beexplored.

Apparatus

1000 mF capacitor, 1kΩ resistor, powersupply, switch, leads, voltage and currentsensors, interface. You may need to 'bias'the voltage to get your readings on screen.

Setting up

Connect the current sensor to socket 1,and the voltage sensor to socket 2.If the sensors are adjustable set a 100mArange on the current sensor and a 10Vrange on the voltage sensor. Some systemsrecognise the sensors you attachautomatically, in others you do thisyourself.

Recording the data

Record for 1 minute. Charge the capacitorand when charged, move the switch toallow it to discharge.

Using the results

Describe the graph you see.What does the graph tell you about theway a capacitor discharges?What factors affect this?Save your data on disc and print thegraph.

Capacitor charge and discharge

Current sensor

Computer

Voltage sensor

Switch

- +

- +


Section

6Experiments

104

How pressure changes withtemperature can be monitored usingsensors. A graph of pressure againsttemperature can be plotted as it happens.After the experiment, the scale of the axiscan be changed to estimate Absolute Zero.

Apparatus

Water bath, flask with bung, delivery tube,interface, temperature and pressuresensors.

Setting up

If desired, flush the flask with dry air, thenseal it.Connect the pressure sensor to socket 1and the temperature sensor to socket 2.If the sensors are adjustable, set a 10kParange on the pressure sensor and a 0-100°C range on the temperature sensor.Some systems recognise the sensors youattach automatically, in others you do thisyourself.Your software may allow you to plot thepressure against temperature as theexperiment proceeds rather thanafterwards.

Recording the data

Record for 10 minutes. Start heating theflask, after 5 minutes allow it to cool.

Using the results

What does the graph tell you about thechange in pressure?What does the graph tell you about thechange in temperature?Use the software to plot the pressureagainst the temperature.What seems to be the pattern betweenpressure and temperature?Set the temperature axis to includeabsolute zero and extrapolate the graphdown to absolute zero.

Pressure & temperature

Computer


Pressure sensor

Water bath

Interface


Section

6Experiments

105

A temperature sensor can be used tostudy the conduction of heat throughdifferent materials. Two temperaturesensors allow a comparison to be made. Inthis experiment strips of metal are heatedin a Bunsen flame and the temperaturechange recorded. The material whichshows the faster temperature rise is abetter heat conductor.

Apparatus

Different metal rods of identical size,clamps, stands, Bunsen burner, tape,interface and temperature sensors. Takecare not to heat the sensors beyond theirmaximum rated temperature.

Setting up

Connect temperature sensors to sockets 1and 2 on the interface. Tape thetemperature probes at the ends of themetal rods. Use the clamps to hold thesensors and rods.Some systems recognise the sensors youattach automatically, in others you do thisyourself.

Recording the data

Record for 5 minutes. Move the rods intothe Bunsen flame and ensure that each isheated equally.

Using the results

How does the graph tell you that themetals are getting hotter?Does the graph tell you if heat is travellingthrough the metal? Could thetemperature probes be getting warmerwithout the heat travelling through themetal?How can you tell which of the rods getshot fastest?What do the graphs tell you about the twometals?

Heat conduction

Computer

Temperature sensor

Metal rods

Temperature sensor Interface


Section

6Experiments

106

A temperature sensor can be used tostudy the insulating properties of differentmaterials. Two temperature sensors allowa simultaneous comparison to be made. Inthis experiment two beakers of hot waterare insulated with different materials andallowed to cool. As they do so a coolingcurve is plotted. The experiment could berepeated to see the effect of wrappingthings in aluminium foil.

Apparatus

Beakers, clamps to hold the probes,stands, hot water, insulating materials,fabric and aluminium foil, interface andTemperature sensors.

Setting up

Connect temperature sensors to sockets 1and 2 on the interface. Wrap one beakerwith fabric.Some systems recognise the sensors youattach automatically, in others you do thisyourself. If the sensors are adjustable, setthem on a 0-100°Crange.

Recording the data

Record for 15 minutes. Pour equalamounts of hot water into each beaker.Repeat the experiment using loosealuminium foil instead of insulator.

Using the results

How does the graph tell you that thewater is getting cooler?How can you tell which of the beakers isgetting cool fastest?When will the insulated beaker reach thesame temperature as the uninsulated one?What does the graph tell you about theeffect of insulation?

Heat insulation

Computer

Interface

Temperature sensor

Insulation

Temperature sensor


Section

6Experiments

107

Two temperature sensors can collectsome interesting information aboutcooling during a change of state. In thisexperiment the temperature of a waterbath increases as a substance cools. Butthe unusual setup here will also show that,during the change of state, heat is lostfrom the substance even though itstemperature remains constant.

Apparatus

Beaker, test tube, water bath, insulationmaterial for the beaker, stearic acid (orwax; benzophenone), test tube rack,interface, Temperature sensors (not FirstSense types - they might be damaged).

Setting up

Connect two temperature sensors tosockets 1 and 2 on the interface.Place one temperature probe in a test tubehalf-filled with Stearic Acid. Warm thetube and probe in a water bath to melt thestearic acid.Some systems recognise the sensors youattach automatically, in others you do thisyourself. If the sensors are adjustable, setthem on a 0-100 range.

Recording the data

Remove the tube from the water bath.Place it in a small insulated beaker, partlyfilled with water.Record for 10 minutes. Stir the stearicacid continuously.

Using the results

How does the graph show you that thestearic acid is getting cooler?What is happening to the watertemperature as this occurs? Why is this?What is happening to the stearic acidwhen the graph is flatter?What happening to the water temperatureas this occurs? Where does the water gainits heat from?

Cooling curve

Computer


Insulation

Cooling substance

Temperature sensor


Section

6Experiments

108

A position sensor is attached to a weightand spring assembly as shown. This can beused to graph the extension of the springwith increasing mass.

Apparatus

Clamps & stand, ruler, spring and masses,interface and position sensor.

Setting up

Connect the sensor to socket 1 on theinterface. Set up the position sensor,spring and masses as shown. You mayneed to do a trial run to arrange theposition sensor so that, with no mass, thearm rests near the top of its range.Some systems recognise the sensors youattach automatically, in others you do thisyourself. You may be able to calibrate themovement of the sensor in absolutedistance units.The software also needs to know that youwill be entering masses, of say, between 0and 50 g via the keyboard.

Extension of a spring

Recording the data

Start recording - you should be promptedto enter a mass value at the keyboard.With no mass on the spring, type 0 for themass.Add a mass to the carrier. Type in 10 forthe new mass. Continue adding massesand entering the total mass each time.

Using the results

How is an increasing load on the springshown on your graph?How does the extension of the springchange with mass?Save your data on disk. Print the graph.

Computer

Interface

Position sensor

Rule


Section

6Experiments

109

A position sensor is attached to a weightand spring assembly as shown. This can beused to study simple harmonic motionand the effects of changing the mass ordamping.

Apparatus

Clamps & stand, spring and masses,interface and position sensor.

Setting up

Set up the position sensor, spring andmasses as shown. Connect the sensor tosocket 1 on the interface. Test the motionof the oscillating weight and check thetime taken for it to stop moving - with oneor many weights. You will need to adjustthe position sensor arm to ensure thatwhen it is still, the screen trace is say,halfway up the screen.Some systems recognise the sensors youattach automatically, in others you do thisyourself.

Recording the data

Record for 30s and displace the weight. Ifyou record for much longer you will losesome of the detail in the graph.Store the graph and make anotherrecording - displacing the weight a bitmore this time.

Using the results

How does the graph describe themovement of the weight?Save your data on disk. Print the graph.

Oscillator motion

Computer

Position sensor

Lever arm

Interface


Section

6Experiments

110

Absorption of thermal radiation

A shiny surface and a black surfaceabsorb heat differently. Usingtemperature sensors or thermocoupleprobes it is possible to compare thetemperatures on two these differentsurfaces. Either the temperatures will beplotted against time on the computer orin the case of the thermocouple, the graphwill rise as the difference between its twoprobes increases.

Apparatus

Radiant heater, two metal containers - oneshiny, one black, interface, temperaturesensors or thermocouple probe/sensor.

Setting up

Connect the sensor to the interface.The software needs to know that you haveconnected this sensor and some systemswill do this for you. If the thermocouplesensor is adjustable, adjust it to expect asuitable difference (say 10 to 20°C)between the two probes.

Recording the data

Record for 5 minutes. When thetemperature difference falls to zero, switchon the radiant heater.

Using the results

If the sensor shows the difference intemperatures, what does the graph tellyou when it moves up the screen?What does the graph tell you when itmoves down the screen?Does the graph tell you which container ishottest?What does your graph tell you about thetemperatures of the two containers?Does you graph stop changing at anypoint? What does this tell you?Save your data on disc and print thegraph.

Computer

Interface

Temperature sensors or Thermocouple sensor

Heater

Black can Shiny can


Section

6Experiments

111

As acid reacts with alkali, heat isevolved. This is the heat of neutralisation.This can be easily monitored using atemperature sensor. In this experimentthe temperature is monitoredcontinuously as acid is added to alkali .

Apparatus

pH Indicator solution, 50 cm3 1 Msodium hydroxide NaOH, 10 cm3 5Mhydrochloric acid HCl, 200 cm3 beaker,interface, temperature sensor.

Setting up

Connect the temperature sensor to socket1 on the interface.Place the temperature probe in a beakercontaining 25 cm3 alkali and pHindicator.Some systems recognise the sensors youattach automatically, in others you do thisyourself. If the sensor is adjustable, set arange of around 40 degrees.

Recording the data

Record for 3 minutes. Add 5 cm3 acid andstir.

Heats of reaction

Using the results

How does the graph show you themixture is getting hotter?When during the reaction is the mixturegetting hotter fastest?When does the mixture start to cool? Whyis this?How would other acids and alkalisbehave?Save your data on disc and print thegraph.

Computer


Reaction mixture


Section

6Experiments

112

Exothermic reactions

A temperature sensor can collectinformation about the heat generatedwhen lime is mixed with water. Thisreaction 'might' be used in a ski bootheating pack. The proportions of themixture are important. If icing sugar isadded to the lime mixture the rate of heatgeneration changes. You can investigatethe results of adding different amounts ofsugar (or water) to the lime and sodetermine the mixture which gives outmost heat for the longest time.

Apparatus

Beakers, insulation for the beaker, testtube, balance to weigh solids, icing sugar,quicklime, plastic gloves, interface andtemperature sensor.

Setting up

Connect a temperature sensor to socket 1on the interface.Place the solid ingredients in a beaker. Putthe temperature probe in a test-tube witha measured volume of water.Some systems recognise the sensors youattach automatically, in others you do thisyourself.

Recording the data

Record for 15 minutes. Add water to thesolids and stir.Repeat the experiment using differentmixtures of lime and icing sugar.

Using the results

How does the graph tell you the mixtureis getting hotter?When during the reaction is the mixturegetting hotter fastest?How long does the heating effect last for?What might the area under each graph bea measure of?How can you decide which mixture is thebest?

Computer

Temperature sensor

Reaction mixture

W ater

Interface


Section

6Experiments

113

Sodium thiosulphate and acid react toform a precipitate. The light sensor can beused, like a colorimeter, to monitor therate of the reaction. In this experiment westudy the effect of different amounts ofacid on the reaction rate. It will also bepossible to study the effect of temperature.

Apparatus

0.1M hydrochloric acid HCl, 0.1 MSodium thiosulphate Na2S204, distilledwater, a sheet of black paper, interface andlight sensor. Bright light source.

Setting up

Set up the light sensor and a beakercontaining 30cm3 of thiosulphate Na2S204.(Better alternative: use a smaller volumein a plastic cuvette made from a pHindicator paper box).Use black paper to shield the beaker fromchanges in the light level. Try not tocompletely cover the chemicals - it helps ifyou can see the chemical changeoccurring.Connect the light sensor to socket 1 onthe interface. Some systems recognise thesensors you attach automatically, in othersyou do this yourself.Start the computer recording and see ifthe trace is on screen. If the Light sensoris adjustable, change its range to get thetrace on screen.

Recording the data

Add 5cm3 acid to the beaker.Record for 90 seconds. Avoid leaning overthe beaker!Replace the beaker and 30cm3thiosulphate solution. Repeat theexperiment using 10 cm3 acid.

Using the results

How does the appearance of the solutionchange during the reaction?What does the graph tell you about theprogress of the reaction?When was the reaction working at itsfastest?What condition did you change? How hasthis affected the graph? How has thisaffected the reaction?Calculate the average gradient of thegraphs. Which part of the graph shouldyou use?Save your data on disk. Print the graph.

Rates: Thiosulphate and acid

ComputerLight sensor

Interface


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Rates: marble and acid

Hydrochloric acid and marble(CaCO3) react to form carbon dioxidegas. The gas can be captured andmeasured using a gas syringe. A positionsensor can be attached to the syringe torecord the rate of the reaction. Thisexperiment shows the effect of surfacearea on the reaction. The effect of acidconcentration could also be explored.

Apparatus

Clamps, bosses, & stands, marble pieces(large, medium and small sizes), 1Mhydrochloric acid HCl, flask, bung,delivery tube, a good gas syringe.Interface, position sensor.

Setting up

Set up the position sensor, flask, 1g oflarge marble pieces and the gas syringe asshown.Connect the sensor to socket 1 on theinterface. Some systems recognise thesensors you attach automatically, in othersyou do this yourself.You may be able to do a two-pointcalibration of the sensor so that thecomputer displays the volume of thesyringe directly.

Recording the data

Place 1g of marble in the flask. Add 5cm3acid when you are ready.Record for 90 seconds.Repeat using different sized marble pieces.

Using the results

How does the graph show the progress ofthe reaction?When was the reaction at its fastest? Howcan you tell?Which part of each graph best shows howfast the reaction was working?Calculate the average gradient of each ofyour graphs to compare them.Save your data on disk. Print the graphs.

Computer

Position sensor

Lever arm

Interface


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As acid drains into alkali the pHchanges. This can be monitored using apH sensor and instantly produce a graphof pH against volume. The volume of acidadded is entered using the keyboard. Theexperiment can be repeated usingdifferent combinations of strong and weakacid.

Apparatus

Burette, stand, magnetic stirrer, indicatorsoln., pH electrode, pH buffer solution,200cm3 0.1 M sodium hydroxude NaOH,50cm3 0.5M hydrochloric acid HCl,200cm3 0.1M ethanoic acid CH3COOH,200cm3 beakers, interface, pH sensor/electrode.

Setting up

Set up a beaker with 20 cm3 alkali &indicator, place on the stirrer. Fill theburette with acid.Connect the pH electrode to the pHsensor. Connect the pH sensor to socket 1on the interface.Place the pH electrode in the beaker ofalkali.

Sensor identification

The software needs to know that you haveconnected a pH sensor. Some systems dothis automatically. You may be able tocalibrate the pH sensor to read correctlyin known pH buffer solution.The software also needs to know that youwill be entering volumes of between 0 and10 cm3 via the keyboard.

Recording the data

Start recording - you should be promptedto enter a volume at the keyboard. Withno acid added, type 0.Add 1 cm3 acid from the burette. Type in1 for the new volume. Continue adding 1cm3 acid and entering the total volumeeach time.

Using the results

When does the pH change most slowly? Isthis at the beginning, the middle or theend of the titration?When does the pH change most rapidly?What does the graph tell you about thechange in pH during a titration?Save your data on disk. Print the graph.

Acid-base titration

Computer

pH sensor

Alkali

Interface


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Acid-base titration

As acid drains into alkali the pH changesand this can be monitored using a pH sensor.Your data logging software will need to have afeature where the volume of acid added can betyped in as you do so. When you want to dosomething a little bit out of the ordinary, icondriven software such SoftLab, Robolab,PASCO's Data Studio are particularly flexibleand allow you to do this in an intuitive way.

Apparatus

Burette, stand, stirrer, pH Indicator solution,pH electrode, pH buffer solution, 200 cm3 0.1M sodium hydroxide, 50 cm3 0.5Mhydrochloric acid, 200 cm3 beakers, interface,pH sensor.

Using the program


Choose Keyboard Entry. Click OK.


Choose pH sensor. Click OK.



Double click the Graph to open a window. Re-position the window.Choose Run, Check & Start.

Enter the volume of acidadded:i.e. type 0 ↵Add 2cm3 acid, let the pHstabilise then,Enter the volume of acidadded:i.e. type 2 ↵Continue like this till thetitration is complete.

An example using icon driven software

Results

From the graph window choose Analysis,Coords and move the pointer over the graph totake readings.If you would like the results in a table, drop aTable on the SoftLab Benchtop , wire it to thegraph and repeat the titration.

Computer

pH sensor

Alkali

Interface

Connect the pH sensor to socket 2.


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Thermometric titration

As acid reacts with alkali the pHchanges and heat is evolved. This heat ofneutralisation can be easily monitoredusing sensors - to produce a graph oftemperature and pH against time. If it isassumed that the burette drains at aconstant rate, then the time will beproportional to the volume of acid. Heatproduction decreases after all the alkalihas been neutralised.

Apparatus

Burette, stand, magnetic stirrer, pHIndicator solution, pH electrode, pHbuffer solution, 200 cm 3 1 M sodiumhydroxide NaOH, 50 cm3 5Mhydrochloric acid HCl, 200 cm3 beakers,interface, temperature sensor, pH sensor.

Setting up

Set up a beaker with 20 cm3 alkali &indicator, place on the stirrer. Fill theburette with acid.Connect the pH electrode to the pHsensor and the sensor to socket 1 on theinterface.Connect the temperature sensor to socket2. Place the temperature probe and thepH electrode in the beaker of alkali.If the temperature sensor is adjustable, seta suitable range of say, up to 40 degrees).You may be able to calibrate the pHsensor to read correctly in known pHbuffer solution.

Recording the data

Record for 2 minutes. Turn on the stirrer.Turn on the burette and let the acid dripin gradually. Ideally try to top up, andmaintain the same head of liquid in theburette.

Using the results

When does the pH change most slowly?Is this at the beginning, the middle or theend of the titration?When does the pH change most rapidly?What does the graph tell you about thechange in pH during a titration?How does the graph show you themixture is getting hotter?When during the reaction is the mixturegetting hotter fastest?At what pH does the mixture start tocool? Why?Save your data on disk. Print the graph.

Computer

Interface

Acid

Temperature sensor

pH sensor

Alkali


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As a candle burns oxygen is used andheat and water are produced. A fewsensors can be used to monitor thisprocess - including a light sensor toindicate when the candle is extinguished.

Apparatus

Candle, bell jar, matches, interface andsensors: temperature, light, oxygen andhumidity sensors.

Setting up

Set up the candle and sensors inside thebell jar and arrange them so that theprobes will be well away from the candleflame.Connect the sensors to the interface. Allowan oxygen sensor time to stabilise. Somesystems recognise the sensors you attachautomatically, in others you do thisyourself.

Recording the data

Record for 3 minutes. Light the candle,cover it with the bell jar. When the candlehas extinguished, readmit air into the belljar.

Using the results

How does the graph show you the candleproduces heat?How does the graph show you the candleproduces water?How does the graph show you the candleproduces light?How does the graph show you the candleuses oxygen?When is the oxygen level at its lowest?Why does the oxygen level increase at theend?Save your data and print the graph.

Burning a candle

Oxygen sensorHumidity sensor

Temperature sensor

Computer

Candle in bell jar

Interface


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With a data logger several sensors canbe used together to monitor the weatherover periods lasting weeks. Suitablesensors include temperature, pressure,humidity, light or even a rotation sensorto check the wind speed. For seriouswork, involving months of weatherrecording, a dedicated weather stationshould be considered.

Apparatus

A data logger and sensors such astemperature, humidity and light sensors.

Setting up

1. Connect the sensors to the sockets onthe data logger.2. Position and fix the sensors in suitableplaces, for example, hang them out of thewindow. If the equipment is placedoutside, keep parts of it in a polythenebag.3. Start the data logger recording.4. After the recording, connect the datalogger to the computer and get thesoftware to transfer the data from the datalogger.

Weather stationAn example using a datalogger

Using the results

See the companion guide, The IT inSecondary Science Book for a worksheetwhere students are asked to look forpatterns in their weather data.

Light sensor

Temperature sensor

Humidity sensor

Computer

Data logger


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This section looks at some of the sensors andequipment you can obtain or indeed may have. It

aims to give an idea of the scope of the technology.Here you will find what is available, what you can useeach sensor for and some practical tips. Later we lookat software.Although no one manufacturer has all of thesesensors, there are all sorts of creative ways to achieveyour needs so you will not need everything.

Breathing movementsConductivityColorimeterDistance / MotionForce / AccelerationHumidityInfra-Red radiationLight levelsTime using light gates, light switches, magnetic switches,pressure pads and other switches.Magnetic fieldOxygen level (air / dissolved oxygen)pH valuesPressure / Low pressure / Barometric pressurePosition or AngleTouch using a pressure matPulse rate / Pulse waveRadioactivityRedoxRotation speedSound levelSpeed of soundTemperature (various ranges from -10 to 110°C)Extreme temperatures (Thermocouple -50 to 1100°C)Heat flowUltra-violet radiationPotential difference and currentMass through an electronic balance

See also:

Sensing glossary Page 10Ideas for data logging and control Pages 11-32


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Air pressure sensor

The sensor can be used as part of aweather station or to measure airpressure changes with altitude. Toavoid tying up the computer for longperiods use it with a remote data logger.

Breathing sensor

♦ Semi-quantitative breathingmeasurements.

Conductivity sensor

♦ Acid-base titrations♦ Precipitation and other titrations.♦ Measuring salinity of rock pools.♦ Environmental (water) monitoring.♦ Conductimetric titrations.Sensor notes:

The probe for this sensor is a conductivitycell. Keep the conductivity cell as far aspossible from the computer to minimiseelectrical noise picked up by the cell. Whentransferring the cell from one solution toanother, rinse the cell in distilled water andshake it to remove drops. Never wipe it. Afteruse wash in distilled water. Store wet or dry.For absolute conductivity measurements, thereading on the computer must be multipliedby the cell constant. This value should bemarked on a tag on the conductivity cell. Thecell constant can also be determined bymaking a measurement of 1.0M KCl whichhas a conductivity of 11.175/Sm at 18’C.

Colorimeter sensor

♦ Lots of chemistry - bleaching,iodine-propanone reaction,thiosulphate-acid.

♦ Lots of biology - starch-iodine-amylase, action of pepsin on milk, oftrypsin on milk or of the proteasesin biological washing powders.

Distance sensor

♦ Direct measurement of distance.♦ Preparing distance-time graphs and

calculating kinetic energy,acceleration and speed: whenwalking, cycling, moving trolleys,bouncing a ball.

♦ Oscillator motion (with a spring heldweight).

♦ Studies of an air track puck; frictionstudies. Conservation ofmomentum.

♦ Investigations into the design of aski jump,

♦ Stopping distances of model cars.♦ Acceleration due to gravity.

Force / Acceleration sensors

♦ Forces involved in lifting, pushing atrolley

♦ Force on a mass going up/down in alift

Humidity sensor

♦ Rate of transpiration and humidity.♦ Moisture in exhaled air.♦ Hygrometry.♦ Weather station.♦ Moisture from burning fuels.♦ Moisture uptake through fabrics.Sensor notes:

Measurements are usually within therange 10-90% humidity. In a movingcurrent of air the sensor responds morequickly. Acetone and organic solventvapours are harmful to the sensor.When the probe is wet, the reading isunreliable.

Sensors


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Infra-Red sensor

♦ Comparing body heat (cold or warmhands). Striking a match.

♦ Measuring radiant heat, IR from afilament lamp, sunlight.

♦ Heat from a ‘Leslie Cube’ or aradiator and the effect of distance onradiation.

♦ Heating effect of current through anichrome wire.

♦ Using a prism to split up light andthen detecting infra red at the endof the spectrum.

Light gates and switches

♦ These sensors are digital sensors sothey respond to 'light' rather thatmeasure it. That response can beused in timing events. Typically youneed two digital sensors - one torespond when an event starts andone for when it stops. They can alsobe used in control systems - such asa sensor for a burglar alarm.

♦ How fast objects move down ramps.♦ Reaction timing♦ Air track measurements♦ Counting pendulum swings or how

often a bird table is visited.♦ See Forces for more.

Light sensor

♦ Monitoring of light levels day/night.♦ Light levels in photosynthesis.♦ Environmental studies.♦ Response of a flash gun using a fast

data logger.♦ As a timing light gate - e.g. to time

the swing of a pendulum.♦ Variation of light intensity with

distance: the inverse square law.♦ Colorimetry in the starch-iodine

reaction. Rate of reaction betweenIodine and propanone.

♦ Turbidimetry of acid-thiosulphatereaction, action of pepsin on milk, oftrypsin on milk or of the proteasesin biological washing powders.

♦ Investigating diffraction andinterference patterns.

♦ Measuring leaf transparency.Sensor notes:

Light sensors have logarithmic or linearranges. The LOG setting will sense thefull range of light intensity. This wouldbe useful in monitoring sunshine. Thelogarithmic type is a bit less suitable forquantitative work. It is however, muchsimpler to use.Diode types can respond much fasterthan light dependant resistor types.The slower type will respond less tointerference such as fluorescent striplighting. The fast type can even pick upAC ripple.


♦ Electromagnetic induction.♦ Hysteresis curve.♦ Magnetic field along a coil.

Manometer / bio pressure sensor

♦ Small volume and pressure changes.♦ Monitoring fermentation.♦ Respiratory rates - gas exchange/

breathing movements of a locust.♦ Use of gas by rusting nails.♦ Osmosis/diffusion experiments.

Sensors


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Oxygen sensor

♦ The effect of changes of temperatureupon oxygen demand by yeast,maggots, locusts and germinatingpeas.

♦ Biological oxygen demand.♦ Use of oxygen in fermentation and

in the manufacture of yoghurt.♦ Use of oxygen by a burning fuels.♦ Solubility of oxygen in water as it

cools.♦ Investigating photosynthesis.♦ Oxygen content of ponds and

aquaria: and the effect of depth.♦ Oxygen content of exhaled air.Sensor notes:

At least twenty minutes before use, fill themembrane cap with electrolyte gel. Avoidintroducing air bubbles. Connect the electrodeto the sensor and leave it hanging in air,switched on to stabilise. To calibrate thesensor simply use air! If desired, also useboiled water as 0% oxygen. If an aquariumpump aerates a cylinder of water for an hourthis can be used as a 100% saturated standardsolution.

After use the electrode can be kept suspendedin deionised water to prevent the electrolytegel from drying out. The usual advice is thatthe electrode should only be kept like thisonly for a week and then it should bedismantled, washed with soapy water andrinsed in deionised water. Experience showsthat the oxygen electrode can be left in aready-to-use condition for many months.However, take great care of the membranecaps - physical damage to the polythenemembrane appears to be a common cause ofpoor readings. Problems in use can be due toa poor connection between electrode andsensor, cleanliness of the electrode tip andcondition of the electrolyte. The best advice isto allow sufficient time for the electrode tostabilise.

Electronic temperature compensation is vitalin experiments where temperature changesoccur.

pH sensor

♦ Rates of reactions where pH changesare involved: urea-urease reaction,souring of wine, making yoghurt,lipase activity on oil.

♦ Acid-base titration,♦ Environmental monitoring (e.g. acid

rain) or soil pH using a special pHprobe.

♦ Carbon dioxide production duringphotosynthesis, growth ofmicroorganisms or respiration.

The pH sensor requires a standard pHelectrode. pH electrodes should not be wipeddry or allowed to dry out.

Pressure sensor

♦ Rates of reactions where gas isevolved.

♦ Gas laws: pressure/volume changes.♦ Measurement of the arterial pulse.♦ Use with a stethograph to monitor

breathing.♦ Measurement of osmotic pressure.

Position / Angle sensors

♦ Measuring plant growth.♦ Responding to animal activity, for

example when attached to a birdfood supply.

♦ Rates of reactions with a gas syringe(e.g. marble-acid rain).

♦ Harmonic motion: oscillatingsprings and pendulums(displacement-time graphs).

♦ Tensile strengths. Bending of abridge. Elasticity and expansion.Extension of a spring.

♦ Breathing movements with aspirometer. Rise of bread dough.

Sensor notes:When the sensor is mounted the'opposite' way up, the output can bemade to decrease or increase as it turns.


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Pressure mat

These sensors are digital sensors so theyrespond to 'pressure' rather thatmeasure it. This can be used in timingevents. Typically you need two digitalsensors - one to respond when an eventstarts and one for when it stops: one ofthe sensors could be a light gate. Theycan also be used in control systems -such as a sensor for a burglar alarm.

♦ Reaction timing.♦ Counting people entering a room.♦ Speed at which things fall.

Pulse sensor

Sensor notes:The pulse sensor can have two kinds ofoutput. One provides a measure ofpulse rate as pulse beats per minute.The other gives an indication of theheart beat and heart action.

Radioactivity

♦ Half-lives, decay curves and thestatistics of decay.

♦ Radioactivity with distance.♦ Absorption of radiation by lead,

aluminium and paper.

The sensor requires a Geiger-Muller tubeto measure radioactivity. Any pulse outputcould be displayed on an oscilloscope orheard via an AC coupled audio-amplifier.

Rotation sensor

♦ Measuring speeds at which the gearsin a gearbox turn.

♦ Wind speed♦ Speed at which a record player,

water wheel, wind mill or motorturn. Show the effect of current onsay, the speed of the motor.

Sound sensor

♦ Sound travel through materials.♦ Attack and decay characteristics of

musical instruments and sounds.

♦ Comparing loudness of sounds.Using a data logger the soundsensor can be taken away from thecomputer to monitor traffic noiseand the dawn chorus of birds.

♦ Sound insulating materials.♦ Amplitude of sound with distance.♦ Comparing waveforms of high and

low sounds (e.g. tuning forks) usingan oscilloscope or fast data logger.

♦ Comparing voice patterns; waveform analysis.

Sensor notes:The sound sensor can measure over therange of 50-110 dB. The sensitivity mayfast or slow. A slow response will holdthe output from short bursts of loudnoise for longer. Some allow the sensorto show the waveform of sounds ofdifferent pitch. To capture this detail adata logger is necessary.

Speed of sound sensor

♦ Speed of sound travel throughmaterials.

♦ Change in speed of sound travel dueto temperature.

Temperature sensor

♦ Energy release by germinatingseeds.

♦ Monitoring respiratory activity.♦ Thawing frozen food.♦ Thermometric titration. Heat of

solution.♦ Cooling curve.♦ Cooling by evaporation.♦ Gas laws + pressure sensor.♦ Variation of resistance of a

thermistor with temperature.♦ Absorption of thermal radiation.♦ Insulation experiments. Studies of

conduction; convection; radiation.♦ Studying the effect of surface area

on heat loss.

Sensors


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Thermocouple and hightemperature sensors

♦ For monitoring the cooking of food.♦ For checking temperatures in

different parts of an oven, a Bunsenflame and comparing thecombustion temperatures ofdifferent fuels.

♦ For studying melting points ofmetals.

♦ For making a cooling curve for oil.♦ For comparing temperatures on

black and white surfaces heated bythe same source.

♦ For comparing double and singleglazing. For comparing insulatione.g. vacuum flasks.

♦ For comparing skin temperatureson different parts of the bodyduring exercise.

♦ For comparing temperatures whendifferent liquids evaporate.

Thermocouple sensor

♦ See Differential temperature andHigh temperature for possible uses.

Heat flow sensor

♦ Transmission of heat throughclothing or building materials suchas plasterboard and glass.

♦ Comparing single and doubleglazing.

Ultra-Violet sensor

♦ Variation in UV light during theday

♦ UV level changes with angle to thesun

♦ Comparing sun creams andsunglasses

♦ Comparing glass, plastic and quartzfor UV transmission.


♦ For current / potential differencemeasurements across resistors, athermistor, a lamp or a diode.

♦ Discharge of a battery or a lead-acidaccumulator,

♦ Surge current and the change inresistance when switching on a lamp.

♦ Output voltage of an electronicoscillator.

♦ Maximum power theory. Dischargeof a capacitor.

♦ Measuring the heating effect of acurrent and specific heat capacity.

♦ Measuring the efficiency of a solarcell or an electric motor.

♦ Induced emf resulting from amagnet moving through a coil.

Balance

♦ For monitoring transpiration.♦ For measuring reaction rates where

a gas is evolved.


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Choosing your software

Your choice of software for data logging is reallyimportant. There are so many issues arising from buying

the hardware - like quality, quantity, cost and compatibility,that it is understandable that choosing relatively inexpensivesoftware is often the last decision to be made.

Choose software no less carefully than a set of textbooks. Tryto use it yourself, see it demonstrated by an expert and alsosee the competition. The software drives the whole system soif it is easy to use all the features you need, you will find eventhe most reluctant users more likely to pick it up and use it.

New versions of software appear year by year. Enhancementsare made and problems fixed. New features, such as theautomatic scaling of axes and automatic recognition ofsensors, can make things easier for pupils. As a result,younger and younger pupils are gaining access to thistechnology. Consequently, it's worth review the software youare using - looking out for upgrades on the web, seeing ifthey solve problems you actually have, every couple of years.

Undoubtedly the best thing to happen to data loggingsoftware was to run in ‘windows environments’.

Modern programs share an easier and common way ofworking. So whether you are using a word processor, aspreadsheet or a data logging program, essential jobs such asprinting and saving are accomplished in pretty much thesame way.

Also, and no less importantly, you can share informationbetween your data logging program and other programs. Itis with this feature that pupils can reap yet more benefitsfrom using the technology. They can write about graphs ortables of results they have copied to their word processor. Orthey can put their results into a spreadsheet where they mayfind a set of features that enhance those of their data loggingprogram.


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There is data logging software that isbrimming with features and there is

software that is easy to use. But what weneed is software that allows us to do whatwe want to do easily. That’s not quite thesame thing.

If you teach at the extremes of the schoolage range then your students willobviously need the simplest or the mostfeature-rich programs. Otherwise, you willprobably need different programs to coverthe different levels of use in school.

At an introductory level, you will want aprogram which is easy to set up to displaysensor readings and line graphs. Theprogram should automatically recognizethe sensors that are plugged in and itshould automatically label and scale theaxes.

A particularly useful feature is automaticrecording over time: that means that therecording continues for as long as youleave it to and to compensate, the graphre-scales itself. You may want to switch thisoff occasionally. The program should beable to record from at least two sensors atthe same time. It should also displayreadings as graphs, as numbers and be torecord for as long as you want - perhapsfor as long as 24 hours in an overnightinvestigation. Another feature which willprove to be essential is the ability to takediscrete readings. So you may want, forexample, to compare the light reflectedfrom different surfaces and plot each lightreading as a separate item on the screen.

At the medium to highest levels thesoftware should do all the above as

well be able to read values off graphs. Itshould measure the difference betweentwo readings and measure the averagegradient of a line.

Other features such as the ability tosmooth out noisy graphs, to plot best fitlines and to export the data for use inother data handling programs are alsoessential.

One more feature will prove to be just asessential: you will want to plot one set ofsensor readings against another. Forexample, you may want to plot pressureagainst temperature, volts against amps oreven pH against a volume typed in thekeyboard. No program should beep youwith meaningless error messages. Yet theydo.

There are a number of situations wherethe standard data logging program doesnot do all you want. You may have anelectronic balance that requires specialsoftware to take readings from it or youmay want to monitor and display changes,such as heart rate, electrocardiograms ortidal volumes in breathing. Although someprogress is being made to address everymeasurement need in a do-it-all datalogging program, you may still need touse dedicated software.

Where to get your software

Every manufacturer of data loggingequipment has a suite of programs to

use with their equipment. These areavailable for almost every make ofcomputer you might find in school. Thisapparently basic point becomes of specialinterest if you use a mixture of computermakes. You just buy different cables andsoftware for each machine and you canthen use the same data logging hardwarewith each.

Manufacturer’s software often has theadvantage of being able to exploit uniquefeatures of their hardware to the full.

Then there is the advantage that havingbought your whole package from onesource, you might rightly expect it towork as intended.

/ continued...


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Working the software ...

... read values from the graph

... read the difference between two points

... smooth or average a 'noisy' graph

... put the graph in your word processed report

... find the slope or gradient of

a graph

After your experiment you can...


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5. Get your experiment ready and start measuring

Before your experiment, you may need to check or

change these settings...

1. Say which interface you are using

2. Say which sensors you are using

3. Say how long you want to measure for

4. Say whether you want a full scale graph or not


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In recent years, software from ‘thirdparties’ has offered special features.

This software has the unusual advantagethat you can use it with differentmanufacturer’s sensors and interfaces. Soyou can have completely different sensorkits running on different computers andwhat you see on each screen is the samefamiliar program.In keeping with the idea of this book notbeing tied to any particular make ofequipment, these ‘third party’ orhardware-neutral programs qualify for amention.

SoftLab - historic note

SoftLab (Homerton College) was a datalogging program that worked with many brands of

data logging hardware. It used a very differentapproach to other software.Instead of pressing a button to start recording datayou first have to assemble, on the screen, theelements you need to perform the experiment. Sowhen you want to collect data from a sensor, youpick up a sensor icon and drop it onto the screen.And when you want a graph as a display tool, youpick up a graph icon and drop that onto the screen.

You can go on assembling tools. There is a bar gaugethat rises and falls with the readings, there is a digitaldisplay and there is a meter display too. In fact, youwill find a rich assortment of tools here which can beassembled in seemingly limitless ways to achieve theresult you want to. In addition there are control andlogic tools that allow you to build control systemswithout the use of a programming language. Theprogram is flexible, quite comprehensive and wellsuited to advanced work.This singular approach forsakes the instant resultsyou can achieve in other programs and focusesattention on the design of the experiment. It mayprove to provide a further enhancement of students’learning in science. Learners aged from 16 yearscould use it well.

Insight

Insight (Leicester University/Logotron)is a data logging program which makes collecting

data from sensors almost instantaneous and theywork with many brands of data logging hardwareavailable.

There is a control panel where buttons control manyof the tasks you need to perform such as starting andstopping recordings and taking reading from graphs.Other features are accessed through menus.There are facilities to manipulate, re-plot and zoomin on the data. For work with timing light gates thereis a separate program supplied as part of thepackage. This not onlyprovides all the tools thattiming experiments require,but also has a simplespreadsheet that allows you toplot x-y graphs. The programis as flexible and comprehensive enough to meetmost teaching needs for students aged from 11upwards.The program is available for Microsoft Windows,RISC-OS and for the Macintosh.

Junior Insight

Junior Insight (Leicester University/Logotron) has a similar look to Insight described

above. The screen layout and the menus are cleanerbecause the more complex analysis tools of Insightmay not be required at junior level. Instead there aresome extra features. For example, you can addpictures to the screen graph and there are icons toshow which sensors are being used. Junior Insightcould be used with learners aged up to 11 years.

Investigate

Investigate (Research Machines - discontinued)was similar in construction to the SoftLab

software described on this page. Again this is a datalogging program which works with most brands ofdata logging hardware available. Being aimed atyounger students it is easier to use. For example,icons are replaced by buttons which do some of thesetting up work for you and all the windows on thescreen sit within one box. There are also featureswhere pictures can easily be added to illustrateexperiment designs on the screen.The program could be used with learners age up to15 years.

Some software titles


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Addresses

Training days

• Roger Frost & IT in ScienceRusset House, Foxton, Cambridge, CB2 6RTTelephone: 01763 209 109. Email press(at)rogerfrost.comWeb: www.rogerfrost.com

Advice, training or support

• Association for Science Education, College Lane,Hatfield. AL10 9AA. Tel: 0707 267411. Fax: 0707266532. Internet: www.ase.org.uk• Becta, Milburn Hill Road, Science Park, CoventryCV4 7JJ. Telephone: 01203 416994 Fax: 01203 411418.Internet: www.becta.org.uk

Books

• The IT in secondary science book by RogerFrost. ISBN 0 9520257 2 8 (from ASE). A richcompendium of ideas for using IT in school - includingan acclaimed topic by topic guide where you will findappropriate applications of IT in your sciencecurriculum. There are also worksheets and sections onusing spreadsheets, graphics programs, word processorsand database programs.• IT in primary science by Roger Frost.ISBN 0 9520257 3 6 (from ASE). A compendium ofideas for using IT in the primary school - there are notonly sections on using sensors (some shared with thisbook), but also on science software, spreadsheets, wordprocessors and database programs.• Data logging in Practice by Roger FrostLooks at the practical aspects of using data loggers inschools and features graph and data handling exercisesISBN 0-9520257-4-4• Software for science teaching by Roger Frost(Out of print) Reviews and grades all the software andCD-ROMs useful in teaching science to all ages.

The suppliers here will be able to equip you to handle thedata logging ideas in this book.

Equipment and software

Australia: Southern Biologicalwww.southernbiological.com

Fisher Education www.fisheredu.com

Commotion, Unit 11, Tannery Road, Tonbridge, Kent,TN9 1RF Telephone: 01732 773399

Data Harvest www.data-harvest.co.ukwww.dataharvest.com

Deltronics www.deltronics.co.uk

DCP Microdevelopments www.dcpmicro.com

Economatics www.economatics.co.ukGriffin & George www.fisher.co.uk

Matrix Multimedia www.matrixmultimedia.co.uk

PASCO UK Scienctific www.pasco.com

Research Machines www.rm.com

Scientific & Chemical Supplies www.scichem.co.uk

Texas Instruments education www.ti.com

Tain www.tain.com.au

Vernier www.venier.com

Valiant www.valiant-technology.co.uk


Section

7Equipment

132

AAcids & Bases 21, 111, 115-

117Assessment 8

CCombustion 118Control systems

homeostasis 17Ideas 65

Humidity tester 70Porch light 66Sound activated 68Temperature control 67, 69, 71

Cooling curve 24, 52-53, 107

EEarth, day & night 55Earthquakes 95Electricity

batteries 24, 96capacitors 24, 103Ohm's law 25, 99-102power 24, 29, 97thermistor 99

Energy topics:batteries 96cooling 107food 14, 85heat 28, 97, 52-57, 105-106

of reaction 111light 30, 46-51radiation 23, 29, 110seeds 14, 84solar radiation 32sound 32, 40-45, 59-60

Environmentmonitoring 15, 19

Enzymes 14-17, 79-80, 87-88

Exercise 52, 56, 74-77

FFood cooking 16Forces

distance-time 26extension of a spring 108friction 55speeds 27

Fuels 21,118

Index

GGas laws 22, 28, 56, 104Gasometry 22Gravimetry 23, 27

HHarmonic motion 31, 109

IInduction 30Interference patterns 25

LLatent Heat 24, 56Life processes

animal activity 12enzymes 15, 79, 80food 13, 14, 85fermentation

16, 79, 80, 86, 87, 88heart beat 19, 74-76keeping warm 34, 36, 52, 55osmosis 18, 89photosynthesis 18, 81, 82plant growth 18, 84, 90respiration 13, 14,

17, 56, 83, 86, 91reaction time 19temperature regul. 12, 17, 71transpiration 20

Light 30, 46-51, 57-58infra-red 32

MMagnetic fields 30, 94, 95Materials

elasticity 25, 108energy content

21, 85, 111, 117-118,expansion 26heat conduction 28, 34,

36, 38, 52-54, 105-106melting point 26, 107

Materials, behaviourconductivity 22gas in solution 22, 26, 91radioactivity 31, 92-93

PPhotosynthesis 18, 81, 82

RRadioactivity 31, 92Reaction rate 21, 79-80,

113-114

Reaction time 19, 55

SSensors

Conductivity 22, 121Distance 26, 121Electronic balance 20, 22, 23Force 27, 121Light 12, 15, 20, 21, 24, 25,

30, 54, 55, 57, 58, 66,79, 80, 81, 82, 113

Light gates 19, 27, 55, 61,122

Motion 121Oxygen 12, 13, 16, 17,

18, 21, 26Pressure 14, 17-18, 28, 56,

76-78, 89, 104, 121, 123-124

Radioactivity 31, 92, 93, 124Current 29, 97, 99, 101-103,

125Heat flow 125Humidity 20, 21, 56, 70,

118-119, 121Infra-red 23, 29, 32, 121Light level 118, 119, 122Magnetic 30, 94, 95, 122Manometer 13, 22, 89, 122Oxygen 81-83, 87-88,

91, 118, 123pH 16, 17, 21, 87-88,

115-117, 123Position 13, 18, 22, 25,

26, 27, 31, 90, 108-109, 114, 124

Pulse 19, 74, 75, 124Rotation 15, 20, 119, 124Sound 12, 32, 59, 60,

68, 124, 125Temperature 12, 14, 19-24,

26, 28-29, 32, 52-57, 67,69, 84-86, 91, 97, 99, 104-107, 111-112, 117-119, 125

Thermocouple 16, 23,110, 125

Ultra-Violet 125Voltage 24, 29, 30, 96-103,

125

WWeather 20, 54, 57, 119

Z ...

lux volt milliRoger Frost

IT in Science Publishing www.rogerfrost.com

ISBN 0-9520277-1-XEAN 9780952025719

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Data logging & controlThe IT in Science book of

A4 front cover 1 of 2 PANTONE 341 and 369 cvc

data logging & control

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