Name: _____________ Class

SCIENCE 9

UNIT D

Electrical Principles & Technology

TS

Mar 2014S9 Unit D: Electrical Principles and Technologies

1.1 Static electricity

Atomic Theory and Electricity• Protons (+) and neutrons (0) are found in the ____________• Electrons (-) _______ around the nucleus• Atoms are __________ because there is a balance between the number of positively charged protons and negatively charged electrons.

Three Laws of electrical charges:1. 2. 3. When combing your hair:(A) Initially, there are equal numbers of protons (+) and electrons (-) on the comb and hair. No net charge.

(B) Combing transfers electrons from the hair to the comb by _________, resulting in a negative charge on the comb and a positive charge on the hair.

Electrostatic charge – An object becomes electrostatically charged by friction, which transfers electrons between two objects in contact.Charge separation occurs when _________________________________________________________________________________

• Static electricity happens when there is an _________________ between two objects. • Electrical Discharge - the ___________________ from one object to another because of this imbalance. Protons of a neutral object attract the charged electrons of the other, and the electrons “jump” to the neutral object. Eg.When you feel a shock when touching metal

• Lightning - lightning is a discharge from the static electricity formed by raindrops __________________________________________.

Van De Graaff Generators (VDGs)• A rubber belt ___________________________, acquiring a charge by friction and the charge is then transferred to the sphere.

• When you touch the sphere, the charge builds up on you. Your hair stands up because the _____ charges in your hair _________.

Do Check and reflect P.278 #1-9

1.2 Current Electricity– Electric current is a steady flow of _____________________ in the same way that water current flows.It is the charge that flows, and the current is defined as the ______ _____ _____________.

– The difference between static and current electricity is that current is the _________________flow of electrons, while static is simply the ________ ____________ of electrons.

Amperes (A): Often called “amp” for short– Measures the rate at which electrical current flows.

Every Electric Circuit Must Contain At Least Three Elements:

1. Energy source: 2. Conductor:(eg. copper wire)

3. Load or form of resistance: resistance can come in many forms. (eg.

)

There is also often a ___________ to control current flow.

Elements of a Circuit• When a circuit is closed, ___________ leave the negative side of the battery and will flow towards the positive side. The flow of electrons past a fixed point is called a “___________” and is measured in amperes or amps.• Voltage is the force that ___________________ through the circuit. The greater the voltage and current, the more work that a circuit can do.

• Voltage (V): A measure of the potential difference between two places in a circuit.– In other words, voltage tells us how much ____________ each charged particle carries.– The higher the voltage, the more energy each particle has.

1.3 Electrical SafetyComing in contact with a power transmission line can prove to be deadly. By touching it, a ____________________ can occur, because

the electricity is trying to find a path to the ground - you can complete the circuit, but it may be fatal.

The Dangers of Electrical ShockHigh voltage power lines carry 50,000V of electricity. However, amperage is more important to consider. • 0.001A will likely not be felt at all, 0.015A to 0.020A will cause a painful shock and loss of muscle control (which means you will not be able to let go of the line). • Current as low as …• Electrical Dangers vary, depending on the situation. When the current can flow easily, it is more dangerous. • Insulators (such as ____________________________) hamper the flow of electricity, but moisture is a good conductor of electricity, so avoid _________ when working with electricity.

Protecting Yourself from Electrical ShockThe Canadian Standards Council issues labels to identify the amount of voltage required to operate electrical devices and the maximum current they use.

Electrical Safety Pointers...• Never handle electrical devices if you are wet or near water• Don't use devices that have a frayed or exposed power cord • Always unplug an electrical device before disassembling it • Don't put anything into an electrical outlet - except a proper plug for an electrical device • Don't overload an electrical circuit, by trying to operate to many devices at once• Avoid power lines • Don't bypass safety precautions when you are in a hurry • Pull on the plug, not the cord or wire• Never remove the third prong from a 3 prong plug

Plugs, Fuses and Breakers

The third prong of a 3 prong plug is a ______________, connected to the ground wire of the building, in case of a short circuit. Fuses and circuit breakers interrupt a circuit when there is too much _________ flowing through it.Fuses contain a thin piece of metal, which is designed to _________if the current is too high.Circuit breakers, on the other hand, trip a spring mechanism, which _______________________________ through the circuit, when there is too much current. It

can be reused over and over (provided the cause of the increased flow is corrected).

The Dangers of LightningA lightning strike can have 30,000A - more than enough to kill you. Avoid being the target of a lightning strike by staying …

• Lightning can also do a lot of damage to a building. Metal _____________ which are connected to the ground with a _____________________, are fixed on the roof of many buildings to prevent damage to the building during an electrical storm.

• Do Check and Reflect P.287 #1-9

1.4 Cells and Batteries• An electrochemical cell supplies a steady _____________.• The electricity comes from _____________________ within the cell.

Dry Cells - electricity-producing cells referred to dry cells are 'dry' because the chemicals used are in a _______.

The chemical reaction in a cell releases free electrons, which travel from the __________ terminal of the cell, through the device that uses the electricity, and back to the _________ terminal of the cell.

Dry cells are made up of two different metals, called ______ in an electrolyte paste.

An electrolyte is a __________________________________ because it contains chemicals that form ions. The electrolyte reacts with the electrodes, making one electrode positive and the other negative. These electrodes are connected to the terminals.

Wet Cells - These are called 'wet' because the electrolyte is a _______ (usually an acid). In a car battery, the electrolyte is ______________ _________.

Electrons travel from the ____________ electrode (zinc) through the device and on to the positive electrode (copper).

Rechargeable CellsNon-rechargeable cells are called ________ cells.The chemical reactions in a secondary cell (_______________) can be reversed by using an external electrical source to rejuvenate the cell.

The cheapest and most common secondary cells are Nickel Oxide and Cadmium (Ni-Cad). The reactants are restored, but the electrodes wear out over time.

• Batteries - _______________________ creates a battery, which is a sealed case with only two terminals.

• Electrochemistry –

• Electrolysis:

Many industries use electrolysis to separate useful elements from solutions.

Electroplating: Silver and Gold plating can make items look expensive.

A thin coating is produced to cover (and often strengthen) the material.

This is often used to protect metal from _______________.

Other Electrochemical Applications Anodizing and Electro-refining are other examples of electrochemical processes• Anodizing is a process that coats aluminum parts with a layer of ____________________, which is much harder than aluminum. It is used in products such as screen doors, airplanes, car parts, kitchenware and jewelry.• Electro-refining is used to remove ________________ from metal.

• Do Check and Reflect P.294 # 1-10 And Section Review P.295 #1-11

S9 UD Section 2.1 Controlling the Flow of Electrical Current

Insulators: Electrons are ________________ to the nucleus allowing little movement, eg.

Conductors: Electrons are free to move to the positive terminal when a voltage source is applied. Eg.

The more charged particles (or ions) present in a ____________, the better it conducts. Pure water will not conduct electricity. ____ water will.

Neon Signs are a circuit where electrons must flow through a gas. Usually the gas would be an insulator, but when current is applied the electrons are ________ and free themselves from the atoms. This creates a mixture of charged particles which conducts electricity. Different gases emit different colors of light.

Semiconductors - At high temps they act like ______________.

-At low temps they act like _______________.Examples:

Superconductors - ________________________________ Some metals act as superconductors at extremely _____ temperatures.

Resistance: A measure of how difficult it is for ___________________. Measured in __________. High resistance creates …

Resistors: allow current to pass through but provides resistance, limiting the current. Read P. 301. How does a polygraph work?

Switches and Variable Resistors

A switch is a device that ________the flow of electrons or … When the switch is open, there is __________, because there is a gap in the conductor. When the switch is closed, the switch becomes the 'gap replacement' and __________________ of electrons to continue. To change the electron flow gradually, a variable resistor, or ___________ is used (eg_________________________________).

Do 2.1 Check and Reflect P. 303 # 1-3,5-9

2.2. - Modeling and Measuring ElectricityModeling VoltageA waterfall is used, as a model, to demonstrate voltage. Water flows when there is a change in the gravitational potential energy (elevation). Electricity will not flow unless there is a change in ____________ ___________ (voltage).

Modeling Resistance and CurrentFlow of water in pipes is used, as a model, to demonstrate resistance. The size of pipe determines the volume of water allowed through it. The amount of resistance, in a circuit, determines the size of the ______________,

Ohm's Law - Georg Simon Ohm, a mathematician, proved a link between voltage (V), current (I) and resistance (R). The unit of resistance was named after him, the ohm.

Ohm's Law states that as long as temperature stays the same: -the resistance of a conductor …-the current is directly proportional to the …

V = I= R =

V = I =

R =

Do 1-3 p. 307

If the temperature of a resistor changes, the resistance changes as well (resistance is usually low when the resistor is _________, and as the temperature increases, so does resistance).

Types of Resistors - Different resistors are used for different applications, especially in electronics. There are many styles, sizes and shapes. The two most common are the wire-wound and carbon-composition types.

1. Wire wound: The _____________________ the wire the higher the resistance.

2. Carbon-composite: By varying the composition and diameter different resistances are available.

Using Test Meters

Voltmeters measure voltage difference (voltage drop) in volts.Ammeters measure current (rate of flow) in amperes.Small currents are measured using galvanometers.Multimeters can measure _____________, _______________ and ______________ in a circuit.

2.3 Analyzing and Building Electrical Circuits

Engineers and designers of electrical circuits use symbols to identify components and connections. A drawing made with these symbols is called a schematic or schematic diagram. Label:

Parts of a Circuit1. A __________ provides energy and a supply of electrons for the circuit.

2. A ________________ provides a path for current.

3. A ______________ mechanism controls current flow, turning it on and off, or directing it into different parts of the circuit.

4. A _________ converts electrical energy into another form of energy.

CircuitsA circuit which is open is said to be off. Sketch:

A circuit which is closed is said to be on (the load is working) because the current is able to flow freely. Sketch:

Circuit Analysis Example – Bulldozer. Label:

Series and Parallel: There are two basic ways in which to connect more than two circuit components:

1. In a series circuit there is only _____________ for the current to flow. If there is a break in a circuit the whole circuit cannot function. Adding components to a series circuit increases the total resistance in the circuit and decreases the current. eg. lights get __________ as you add more.

2. In parallel circuit there are ___________ pathways for the current to flow. Components in the circuit can have their own pathway to the current source. A break in one section of the circuit will ____________ components in another section of a circuit. Adding resistors in parallel decreases the total resistance of the circuit.

Applications of Series and Parallel Circuits

House Wiring – uses _________________ circuits.

Microcircuits are made up of transistors and resistors built on an extremely small scale.

Microcircuits (Integrated Circuits) - transistors are used with three layers of specially treated silicon, with the middle layer receiving a small voltage, allowing it to control the voltage in the outer layers. This allows the transistors to act as switches.

Do Check and Reflect p. 316, # 1-11.

S9 UD 3.1 Energy Forms and Transformations

Nature of Energy

Energy is all around you. Energy is …

It is estimated that it would take approx. 2800 h of strenuous manual labor to produce as much energy as one average Canadian uses in one day.In other words: A team of ______ strong people working __________ straight!

James Joule (1818-1889) - Studied energy. He proved that mechanical work and electricity can produce _____ and vice-versa.Unit of measure for energy =

There are Four Common forms of energy:

1. Chemical Energy - Energy stored in __________ and released when chemicals react. It is potential or stored energy in … Eg. ______________________…bonds are broken to release energy for your body to store and use.

2. Electric Energy - The energy of _____________________. Electrical energy is transferred when electrons travel from place to placeExamples: Power lines carry electricity, …

3. Mechanical Energy -Energy of ___________, the energy possessed by an object because of its motion or its potential to move.

4. Thermal Energy - Total kinetic energy of all the particles in a substance. The ______________________________ the more kinetic energy it has.Examples:

TWO CUP ANALOGY: Compare two cups holding equal amounts of water: the one containing _______ thermal energy will feel warmer

Energy Conversions - All forms of energy ….

Law of Conservation of Energy: Energy cannot be …

TRANSFORMATIONS OF ENERGY: What energy transformations are taking place?

Input Energy Device Output energyToaster

Chemical energy lightSolar CalculatorCar battery

Transformations Involving Chemical and Electrical Energy Thermocouple: A device that converts …

Made of 2 different metals (bimetal) joined together that conduct heat at slightly different rates. When heated the difference in conductivity results in ..

The higher the temperature difference between the two metals, the greater the amount of

____________________ produced. A

Thermocouple can be used as a thermometer in extreme ______temps. or difficult to access places.

Scientists are currently researching ways to use the Ocean’s natural thermal energy differences to generate electricity. (p.323)Now do Check and Reflect P.323 #1-9

3.2 Energy Transformations Involving Electrical and Mechanical Energy

1820: The Hans Christian Oersted Demonstration A compass needle is deflected by the magnetic field of a …He proved that a current flowing through a wire creates a magnetic field around the wire.

1831: Michael Faraday produces first electric motor, proving that electromagnetic forces could produce ….

How a motor works Types of Magnets 1. Permanent magnet- a _____________________ which remains magnetized for a long period of time (like fridge magnets)

2. Electromagnet - a coil of ________ (usually with an iron core ) which when attached to a _____________ has magnetic effects. Advantage: you can turn it off and on… like the ones used at car impounds/ wreckers)

Yes, if you wrap a piece of metal in a current-carrying wire you get…an ELECTROMAGNET!!!!

1. Wrap a piece of metal in …2. Hook the wires up to a …3. Reversing the wires reverses the current AND

reverses the polarity of the magnet.

A simple Electric Motor requires the interaction of a permanent magnet and an electromagnet. Strong electromagnets are made by winding wire into a coil around an …

How do you keep an electromagnet spinning in a magnetic field to make the motor run? Let’s look at the St. Louis Motor…

Label the St. Louis Motor

Parts of the motor:Armature - Commutator - a split ring that ________ the flow of electricity for a moment and then ______________ the flow in the coil. When the contact is broken, so is the magnetic field

Brushes - reverse the flow of electricity through the electromagnetic coil, make contact with commutator by …

The poles of the armature are attracted to the opposite poles of the permanent magnet. They …

At 180˚, the contact is broken and the poles are …

The split-ring commutator breaks the flow of electricity for a moment and then reverses the …

What does changing the polarity do?

This keeps the motor …

The armature (the rotating shaft with the coil wrapped around it) continues to spin because of momentum, allowing the brushes to come into contact once again with the …

The poles keep being reversed as the current flow is reversed through the coil thus continuously …

Q: Explain the steering wheel analogy to show how the split-ring commutator helps the armature spin continuously. (p.328)

AC or DC Current DC = AC =

Electrons flow … Electrons move …

Most battery operated things use DC Wall outlets

Transformers - Power companies generate AC power because with AC, transformers can be used to change the amount of voltage with minimal energy loss. Some transmission lines carry 500 000 V. This needs to be ___________ before it can be used in your home.

Transformers: a current-carrying wire is wrapped around one side of an iron ring called a core. This is the primary coil. A secondary coil of wire is wrapped around the other side of the core. Current flowing through the primary coil generates an …

1. Step-down Transformers - reduce voltage. _______ windings on the primary coil. __________ windings on the secondary coil.

2.Step-up Transformers - increase voltage. _________ wraps around primary coil. ________ wraps around secondary coil.

Generating Electricity

1831: Michael Faraday discovers ....

Electric current can be generated by …

Today large generators move massive coils of wire rotating between powerful magnets to generate enough electricity to power entire cities.1. DC Generator - is structurally the same as a DC motor. If electricity is passed through a DC generator, it will spin like a motor.

2. AC Generators - As the motor turns one side of the coil moves up between the magnets and the other side moves down. Current is induced in the coil. As the generator continues to rotate current is induced in the coil in the opposite direction, due to two slip rings. This reversal of current every ½ rotation generates …

Types of Generators:

Now Do Check and Reflect P.331#1-4,7-10

Section 3.3 Measuring Energy Input and Output

A. Power:

Measured in Watts (W)1 Watt =

Power is calculated by multiplying current x voltage P = IV P = power in … I = current in …

V = voltage in …

Example: An electric stove runs on 240 V and draws 30 A of current. How much power does it use?

V = 240 VI = 30 AP = ?

B. Energy:

Measured in Joules (J).

E = Input power x time device operates E = Pt

E = energy inP = power in t = time in

Example : A 800W microwave runs for 3 minutes. How much energy does it use?

P= 800Wt= 3min E= ?

Kilowatt HoursJoules are a very small unit of measure. A more common way to

measure energy is to use kilojoules or kilowatt hours. The

formula for energy remains the same, but we use KW for power and hours for time.

E= Pt J = KJ =

Energy Dissipation

Law of Conservation of Energy:

However, the output energy of a device is almost always less than the input energy. Why? Some of the energy has dissipated as ________ or other forms of unusable energy (like sound).

No mechanical system is 100% percent efficient. Therefore, the output energy will always be _________ than the input energy. This is due to …

C. Efficiency Calculations

% efficiency =

Example: A typical gas powered SUV produces 81 KJ of useful output energy for every 675 KJ of input energy (supplied by the fuel). Calculate the efficiency of the SUV.

Easiest way to solve is to use a ratio

Eout = 81 J =

Ein 675 J

Comparing Efficiencies• Florescent lights are about ____ more efficient than incandescent lights.• Arc-discharge lights (streetlights) are even more efficient.• Hybrid gasoline-electric vehicles are _____ efficient than gas-powered vehicles.Do Check and Reflect P.338 # 1-9

3.4 Reducing the Energy Wasted by Devices

Devices that have an energy-efficient design are an important consideration for the consumer, because these devices use less …

Energy costs money and it also affects the environment, so reducing energy consumption is a good practice.

Limits to EfficiencyElectric heater come very close to being 100% efficient, but devices which convert electricity to other forms can never be 100% efficient.

Some energy is lost, or dissipated in a form that is not useful output. Friction causes thermal energy to be lost, or dissipated, in many devices.Increasing EfficiencyIncreasing the efficiency of a device depends on its purpose. The easiest way to increase efficiency in many devices is to reduce friction, as much as possible.eg. …

Insulating a device from heat loss is also another practical way to increase efficiency. Using capacitors (formerly condensers) in electrical circuits is also another way to increase efficiency.

• Check and Reflect P.342 #4,5,6 and Section Review P.343

S9 UD 4.1 Electrical Energy Sources and Alternatives

1. Using Heat to Generate Electricity65% of all electric power is generated by burning fossil fuels such as coal, oil, or natural gas. Most of the fossil fuel used in power plants is coal. In coal-fire generating plants, the coal is first crushed into a fine powder. It is then blown into a combustion chamber and burned. The heat from the burning coal boils water and superheats the resulting steam to a high temperature and pressure. This high pressure steam drives a large turbine. The turbine is long shaft with many fan blades. Steam striking the blades turns the turbine. The turbine shaft rotates large electromagnetic coils in the generator to produce electricity. Oil or natural gas can be burned in the combustion chamber instead of coal.

2. Nuclear fission is the splitting of the atoms of a heavy element such as uranium. The nuclear fission takes place in a nuclear reactor. The splitting of the atoms releases an enormous amount of energy. This release of energy is used to produce high-pressure steam that drives the turbine.

3. Geothermal energy is energy that is derived from the internal heat of the Earth. Hot water and steam naturally come to the Earth’s surface after being heated by hot rock within the Earth’s crust. The steam can be channeled through pipes and used to drive turbines.

4. Biomass is biodegradable waste such as agricultural waste or composting that can be used as an energy source for steam-driven generators.

5. Cogeneration is the use of waste energy from another process, such as heating or generating electricity. The process of manufacturing glass uses very high temperature furnaces. The waste heat from the manufacturing process can be used to produce steam to drive a turbine to generate electricity.

6. Using Water Power to Generate Electricity - About 20% of the world’s electricity is generated by hydro-electric power plants. These plants capture the energy of falling water. Most hydro-electric power plants use a dam built across a river to store water in a reservoir. Water is directed through a channel called a penstock to a large paddle-covered turbine. The rushing water rotates the turbine which is connected to a generator in the same way as a steam-driven turbine.

Alternative Energy Sources7. Moving water from ocean tides can also power turbines that run generators.

8. Wind energy can be harnessed to turn a shaft. A number of wind-powered generators can be connected together in wind farms to produce large amounts of electrical energy.

9. Solar cells use the photovoltaic effect to produce electricity. Today’s silicon-based solar cells are much more efficient than the first solar cells. Eg. calculators, switches for automatic street lights and burglar alarms

10. Fuel cells generate electricity directly from a chemical reaction with a fuel such as hydrogen. The hydrogen comes from sources such as gasoline or alcohol.

Renewable and Nonrenewable Energy• Nonrenewable resources cannot be replaced as they are used up. Alberta’s fossil fuel resources (coal, oil, and natural gas) are nonrenewable resources. • Renewable resources can be renewed or replenished naturally in relatively short periods of time. Wind energy, solar energy, geothermal energy and biomass are renewable resources. Trees are a renewable resource if they are managed carefully.

4.2 Electricity and the EnvironmentEvery method of generating electricity affects the environment. Some methods create undesirable by-products that can have negative effects on human health and the environment.

Air Pollution - The burning of fossil fuels results in the release into the atmosphere of many problem-causing substances. • Fly ash is airborne ash that is produced from burning coal. Fly ash contains small amounts of mercury which is a poisonous metal that can damage the nervous system. • Some of the most harmful molecules that are released from burning coal are sulfur dioxide (SO2(g)), nitrogen oxides (NOx(g)), and carbon dioxide (CO2(g)).

Other Environmental Effects

• Strip-mining techniques are used when deposits of coal are near the surface. Plants, animals, soil, and rocks are cleared away above the coal deposits so the coal can be mined. The land can be reclaimed by replacing the soil and plants; however the original natural environment is usually not fully restored.

• Oil and gas wells can release poisonous gases into the environment. Concentrations of chemicals around wells are monitored for safety.

• Steam turbines often release large amounts of warm water into nearby lakes and rivers. Increases in water temperature can alter freshwater ecology and can sometimes kill fish.

• Nuclear power plants, hydro-electric power plants, wind farms, the process of making solar cells, geothermal plants, and generators that uses tidal or wave energy all can have negative effects on the environment. However, the green sources of energy – especially wind, tide, and geothermal – harm the environment much less than fossil fuels do.

Conserving Energy and Nonrenewable ResourcesThe main benefit of conserving energy and nonrenewable resources is less pollution. Also, temporary shortages of resources can cause hardship and price jumps. When fuel prices skyrocket, poorer countries cannot afford the energy they need.

A Sustainable FutureSustainability means using resources at a rate that can be maintained indefinitely. Without sustainable energy use, future generations may not be able to support themselves. Decisions made with sustainability in mind can involve compromise – taking the bus may not be as convenient as driving your car, however, this will conserve fuel.

4.2 Electricity and the Environment

Reference: read page 351 - 353 in Science in Action 9 text.

Generating electricity has negative effects on _____________________ and the

______________________________.

Air Pollution

What is fly ash? ________________________________________________________

______________________________________________________________________

Why is the release of this fly ash a concern? __________________________________

______________________________________________________________________

Three Major Molecules Released in the Atmosphere and their Effects Molecule Effect ______________________ _________________________

______________________ _________________________

______________________ _________________________

Other Environmental Effects What are two major environmental effects? Explain their effect on the environment.

a. __________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

b. __________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

What does the term sustainability mean?

______________________________________________________________________

What does the expression "Having a sustainable future" mean to you.?

______________________________________________________________________

______________________________________________________________________

______________________________________________________________________

______________________________________________________________________

____________________________

4.3 Electrical Technology and Society

Benefits of Electrical TechnologiesElectrical technologies have improved our standard of living. Most improvements or inventions have come as a result of a desire to improve speed, efficiency or convenience. This has resulted in freeing up people's time to do other things.

Drawbacks of Electrical TechnologiesMore technology means more resources are needed to manufacture and operate them, making sustainability more difficult to achieve. As technology advances, obsolete devices become waste, adding to our problems of waste disposal. Some technologies are too expensive for some countries to adopt, leading to isolation and exclusion.

Computers and Information Computers have revolutionized the way we accomplish many tasks, including writing, calculations and communications. Computers use binary numbers (0s and 1s) to store and transmit data which has led to the digital technology era.

Electricity and ComputersElectrical current is used in one way or another in storing or transmitting information. Lasers, photodetectors, and electrical pulses all enable electronic devices to complete the tasks they are made to do.

A computer hard drive uses electrical pulses to record and transmit information, by using an aluminum or glass disk, with a thin layer of magnetic material that spins at up to 300km/h. The electrical pulses are sent to an arm with read and write heads, which are magnetic coils that magnetize spots on the spinning disk.

• Reading - magnetic spots induce current in the electromagnetic coil, reproducing 0's and 1's in the original signal and are sent to the computer's processor.

• Writing - electrical signals are responded to from the computer's processor.

Electrical Transmission of InformationElectrical signals are sent from computer to computer throughout the world, making the storage and transmission of information compact, easy and relatively cheap. Concerns with this ease are access, privacy and safety.

• Misleading or false information is also a problem and the ‘information explosion’ has created other storage, handling and access problems. Search engines help locate some of the information you may be looking for, but they cannot access everything.

4.3 Electrical Technology and Society

Reference: read page 354 - 359 in Science in Action 9 text.

In _________________ the first ________________________to place when

________________________________invented the ___________________

Benefits of Electrical Technologies

Most ______________________ or ____________________ come from a desire for

_________________________ and _____________________________.

Drawbacks of Electrical Technologies

More ____________________ means that more ____________________ are needed

to

___________________ and ____________________ devices.

Computers and Information

__________________ have revolutionized the way we accomplish many tasks

including:

a. _______________________

b. _______________________

c. _______________________

Explain what binary numbers are. ______________________________________________________________________

______________________________________________________________________

______________

Explain how a compact disc (cd) works.

______________________________________________________________________

______________________________________________________________________

______________

Computer hard drives also use electricity to record and transmit information.

Electrical Transmission of Information

Why is electronic storage of information important to society? ______________________________________________________________________

______________________________________________________________________

______________

What is information overload? ______________________________________________________________________

______________________________________________________________________

______________

Various types of ________________________ were developed for the Internet to sort through the vast amounts of information.