2.1 electricity - standard demand - qs · use your knowledge of energy sources as well as...

of 62

2.1 Electricity - Standard Demand – Questions

Q1. Figure 1 shows a circuit diagram containing two identical lamps arranged in parallel.

The reading on the ammeter is 186 mA.

Figure 1

(a) Which statement about the current through the lamps is true?

Tick one box.

The current through both lamp P and lamp Q is 0.093 A




(1)

(b) One of the lamps breaks and is not replaced.

Which statement about the current in the other lamp is true?

Tick one box.

The current through the lamp is 0.093 A


of 62



(1)

(c) Figure 2 shows a circuit that can be used to alter the brightness of a lamp.

Figure 2

The resistance of the variable resistor is increased.

What effect will this have on the brightness of the lamp?

Explain your answer.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (2)

(d) When the potential difference across the lamp is 3.3 V, the current is 0.15 A.

Write down the equation that links current, potential difference and resistance.

Equation ___________________________________________________________ (1)

(e) Calculate the resistance of the lamp.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Resistance = __________________ Ω (3)

(f) Sketch a current–potential difference graph for a filament lamp.

of 62

(1)

(Total 9 marks)

Q2. A student used electrical circuits to investigate the relationship between resistance, potential difference and current.

Figure 1 shows how the student connects the first circuit he set up.

Figure 1

(a) The circuit does not work.

Draw the correct circuit. (2)

(b) The student then sets up the circuit correctly.

Look at Figure 2.

Figure 2

of 62

What is the reading on the voltmeter?

___________________________________________________________________ (1)

(c) The student then set up a circuit to investigate how resistance affects the brightness of a lamp.

Figure 3 shows the circuit he set up.

Figure 3

The student increases the resistance of the variable resistor.

What effect does this have on the brightness of the lamp?

Explain your answer.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (2)

(d) Write down the equation that links current, potential difference and resistance.

___________________________________________________________________ (1)

(e) When the potential difference across the lamp is 3.3 V the current is 0.15 A.

Calculate the resistance of the lamp in the student’s experiment.

of 62

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Resistance = _________________ Ω (3)

(Total 9 marks)

Q3. (a) Figure 1 shows the inside of a battery pack designed to hold three identical 1.5 V

cells.

Figure 1

Which one of the arrangements shown in Figure 2 would give a 4.5 V output across the battery pack terminals T?

Figure 2

(1)

(b) Figure 3 shows a variable resistor and a fixed value resistor connected in series in a circuit.

Figure 3

Complete Figure 3 to show how an ammeter would be connected to measure the current through the circuit.

of 62

Use the correct circuit symbol for an ammeter. (1)

(c) The variable resistor can be adjusted to have any value from 200 ohms to 600 ohms.

Figure 4 shows how the reading on voltmeter V1 and the reading on voltmeter V2 change as the resistance of the variable resistor changes.

Figure 4

(i) How could the potential difference of the battery be calculated from Figure 4?

Tick () one box.

9 + 3 = 12 V

9 – 3 = 6 V

9 ÷ 3 = 3 V

Give the reason for your answer.

______________________________________________________________

______________________________________________________________ (2)

(ii) Use Figure 4 to determine the resistance of the fixed resistor, R.

of 62

Resistance of R = ___________ Ω


______________________________________________________________

______________________________________________________________ (2)

(iii) Calculate the current through the circuit when the resistance of the variable resistor equals 200 Ω.

______________________________________________________________

______________________________________________________________

______________________________________________________________

Current = ___________ A (3)

(Total 9 marks)

Q4. An electric current is a flow of electrical charge through a circuit.

(a) Complete the sentence.

Use a word from the box.

atoms electrons ions molecules

Metals are good conductors of electricity because electrical charge is transferred

by delocalised __________________________ (1)

(b) Draw one line from each symbol to the name of the component.

Standard symbol Name of component

of 62

(3)

(c) The table below shows information about some electrical appliances.

Electrical appliance Power in watts

Hairdryer

1500

Kettle

2500

Electric hob

3000

Television

360

A student plugs all four of the appliances into one multi-way socket.

The mains electricity is 230 V.

The highest safe current in the socket is 30 A.

Explain why it is not safe to use all four appliances at the same time.

of 62

In your answer you should:

• calculate the total power needed

• use the equation

current = power ÷ potential difference

to calculate the total current needed.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (4)

(d) The figure below shows how electrical power is transferred from power stations to consumers using the National Grid.

Transformer 1 is a step-up transformer.

Explain why step-up transformers are used in the National Grid.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (3)

of 62

(e) What is the purpose of Transformer 2?

___________________________________________________________________

___________________________________________________________________ (1)

(f) In a power station 900 MJ of thermal energy were released by burning natural gas.

Write down the equation that links efficiency, useful input energy transfer and useful output energy transfer.

___________________________________________________________________ (1)

(g) In a power station 900 MJ of thermal energy were released by burning natural gas.

Only 405 MJ was generated.

Calculate the efficiency of this energy transfer.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Efficiency = _________________ (2)

(Total 15 marks)

Q5. A student investigated how length affects resistance of a wire.

Figure 1 shows the circuit the student used.

Figure 1

(a) The student took measurements using the meters X and Y.

Name meters X and Y.

of 62

Meter X ____________________

Meter Y ____________________ (2)

The table shows the results.

Resistance in Ω

Length in m Test 1 Test 2 Test 3 Mean

0.100 0.66 0.67 0.74 0.69

0.200 1.36 1.40 1.34 1.37

0.300 2.02 2.02 2.03 2.02

0.400 2.77 2.72 2.68 2.72

0.500 3.37 3.35 3.40 3.37

0.600 4.03 4.02 3.96 4.00

(b) For which length of wire are the readings of resistance the most precise?


Length = ____________________ m

Reason ____________________________________________________________

___________________________________________________________________ (2)

(c) Why did the student do three tests and calculate a mean?

___________________________________________________________________

___________________________________________________________________ (1)

(d) Write the equation that links current, potential difference, and resistance.

___________________________________________________________________ (1)

(e) The potential difference across a piece of wire is 2.1 V

The current in the wire is 0.30 A

Calculate the resistance of the wire.

Write any equation that you use.

___________________________________________________________________

___________________________________________________________________

of 62

___________________________________________________________________

Resistance = ____________________ Ω (3)

Figure 2 shows a graph of the results.

Figure 2

(f) What is the label for each axis of the graph?

x-axis ______________________________________________________________

y-axis ______________________________________________________________ (2)

(g) What conclusion can be made from the graph in Figure 2?

___________________________________________________________________

___________________________________________________________________ (1)

(Total 12 marks)

Q6. A small community of people live in an area in the mountains. The houses are not connected to the National Grid.

The people plan to buy an electricity generating system that uses either the wind or the flowing water in a nearby river.

Figure 1 shows where these people live.

of 62

Figure 1

© Brian Lawrence/Getty Images

(a) It would not be economical to connect the houses to the National Grid. Give one reason why.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (1)

(b) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.

Information about the two electricity generation systems is given in Figure 2.

Figure 2

The wind turbine costs £50 000 to buy and install.

The hydroelectric generator costs £20 000 to buy and install.

The average power output from the wind turbine is 10 kW.

The hydroelectric generator will produce a constant power output of 8 kW.

Compare the advantages and disadvantages of the two methods of generating electricity.

Use your knowledge of energy sources as well as information from Figure 2. (6)

(Total 7 marks)

Q7. Some electrical appliances use electricity from the mains supply and some use electricity from a battery.

(a) Explain the differences between the current supplied by the mains supply and the current supplied by a battery.

of 62

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (2)

(b) Which set of units correctly links current, potential difference and power?

Tick one box.

one watt = one volt × one amp

(1)

Electrical appliances can be connected to the mains supply using three-core cables.

The cables contain the mains wires.

(c) What are the colours of the insulation around the wires?

Tick one box.

Earth Live Neutral Tick one box

Blue Brown Green and yellow

Blue Green and yellow Brown

Brown Blue Green and yellow

Brown Green and yellow Blue

Green and yellow Blue Brown

Green and yellow Brown Blue

(1)

(d) Touching the live wire of an appliance is dangerous when the appliance is connected to the mains electricity supply.

Explain why.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

of 62

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (4)

(Total 8 marks)

Q8. A student investigates how the length of a piece of wire affects its resistance.

The diagram shows the apparatus used.

(a) What is the length of wire between the two crocodile clips shown in the diagram?

Length = ____________________ cm (1)

(b) Write the equation which links current, potential difference and resistance.

___________________________________________________________________ (1)

(c) For the experiment shown in the diagram, the student recorded: • a potential difference of 3.22 V • a current of 2.18 A

Calculate the resistance of the length of wire between the crocodile clips.

Give your answer to 3 significant figures.

of 62

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Resistance = ____________________ Ω (4)

(d) The student used constantan wire.

The resistance of constantan only changes a small amount when its temperature changes.

Suggest why using constantan is an advantage in this experiment.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (2)

The table shows the student's results.

Length in cm Resistance in Ω

20.0 1.67

30.0 2.49

40.0 3.31

50.0 5.26

60.0 4.98

70.0 5.78

80.0 6.65

(e) One of the results in the table is anomalous.

For what length of wire is the resistance anomalous?

Length = ____________________ cm

of 62

(1)

(f) What could have caused the anomalous result?

Tick one box.

The ammeter gave a reading that was too low.

The wire was shorter than the measured value.

The temperature of the wire decreased.

The voltmeter gave a reading that was too low.

(1) (Total 10 marks)

Q9. (a) A washing machine is connected to the mains electricity supply using a cable and

three-pin plug.

Figure 1 shows a three-pin plug.

Figure 1

Name the materials used in the structure of a plug. Give the reason why each material is used.

Pin ________________________________________________________________

___________________________________________________________________

Outer case _________________________________________________________

___________________________________________________________________ (1)

(b) The three-pin plug contains a fuse. The fuse is connected to one of the wires inside the cable.

(i) Which one of the wires inside the cable is the fuse connected to?

______________________________________________________________ (1)

(ii) The fuse is a thin wire inside a closed glass tube. The wire acts as a resistor.

of 62

What effect does a current through a wire have on the wire?

______________________________________________________________ (1)

(iii) The power of the washing machine varies between 0.7 kW and 2 kW depending on which part of the wash cycle is operating.

Calculate the maximum current drawn from the mains electricity supply by the washing machine.

The mains electricity supply is at a potential difference of 230 V.

______________________________________________________________

______________________________________________________________

______________________________________________________________

Current = __________________________ A (2)

(c) Figure 2 shows how the mains electricity cable is connected to the washing machine.

The earth wire is connected to the metal case of the washing machine.

Figure 2

If a fault makes the metal case live, the earth wire and fuse inside the plug prevent the mains cable from overheating and causing a fire.

Explain how.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

of 62

(2)

(d) New research has shown that many people underestimate the hazards of using mains electricity.

It is important that people do understand the hazards of using mains electricity.

Suggest why.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (1)

(Total 9 marks)

Q10. The current in a circuit depends on the potential difference provided by the cells and the total resistance of the circuit.

(a) Figure 1 shows the graph of current against potential difference for a component.

What is the name of the component?

Draw a ring around the correct answer.

diode filament bulb thermistor

(1)

(b) Figure 2 shows a circuit containing a 6 V battery.

Two resistors, X and Y, are connected in parallel.

The current in some parts of the circuit is shown.

of 62

(i) What is the potential difference across X?

Potential difference across X = _______________ V (1)

(ii) Calculate the resistance of X.

______________________________________________________________

______________________________________________________________

Resistance of X = _______________ Ω (2)

(iii) What is the current in Y?

Current in Y = _______________ A (1)

(iv) Calculate the resistance of Y.

______________________________________________________________

Resistance of Y = _______________ Ω (1)

(v) When the temperature of resistor X increases, its resistance increases.

What would happen to the: • potential difference across X

• current in X

• total current in the circuit?

Tick ( ) three boxes.

Decrease Stay the same Increase

Potential difference across X

of 62

Current in X

Total current in the circuit

(3) (Total 9 marks)

Q11. (a) Figure 1 shows the current−potential difference graph for three wires, A, B and C.

(i) Using Figure 1, how can you tell that the temperature of each wire is constant?

______________________________________________________________

______________________________________________________________ (1)

(ii) Which one of the wires, A, B or C, has the greatest resistance?

Write the correct answer in the box.

Give a reason for your answer.

______________________________________________________________

______________________________________________________________

______________________________________________________________ (2)

(b) A student measured the resistance of four wires.

The table below shows the resistance of, and other data about, each of the four wires, J, K, L and M.

of 62

Wire Type of metal

Length in cm

Diameter in mm

Resistance in …….

J copper 50 0.17 0.36

K copper 50 0.30 0.12

L copper 100 0.30 0.24

M constantan 100 0.30 7.00

(i) The last column of the table should include the unit of resistance.

What is the unit of resistance?

______________________________________________________________ (1)

(ii) The resistance of a wire depends on many factors.

Look at the table. Which two wires from J, K, L and M show that the resistance of a wire depends on the length of the wire?

Wire

and wire


______________________________________________________________

______________________________________________________________

______________________________________________________________ (2)

(iii) A student looked at the data in the table and wrote this conclusion:

‘The resistance of a wire depends on the type of metal from which the wire is made.’

The student could not be certain that her conclusion is true for all types of metal.

Suggest what extra data is needed for the student to be more certain that the conclusion is correct

______________________________________________________________

______________________________________________________________

______________________________________________________________ (1)

of 62

(c) The resistance of a wire can be calculated using the readings from an ammeter and a voltmeter.

(i) Complete Figure 2 by drawing a voltmeter in the correct position in the circuit. Use the correct circuit symbol for a voltmeter.

(1)

(ii) In a circuit diagram, a wire can be represented by the symbol for a resistor.

In the box below, draw the circuit symbol for a resistor.

(1)

(Total 9 marks)

Q12. A student finds some information about energy-saving light bulbs.

(a) A 30W light bulb uses 600J of electrical energy in a certain period of time. In that time, it produces 450 J of light energy. The rest of the energy is wasted.

(i) Calculate the energy wasted by the light bulb in this period of time.

______________________________________________________________

Wasted energy = _________________ J (1)

(ii) What happens to the energy wasted by the light bulb?

______________________________________________________________

______________________________________________________________ (1)

(iii) Calculate the efficiency of this light bulb.

of 62

______________________________________________________________

______________________________________________________________

Efficiency = ______________________________ (2)

(iv) Calculate the period of time, in seconds, during which the 600 J is provided to the 30 W light bulb.

______________________________________________________________

______________________________________________________________

Time = _____________ s (2)

(b) A company that makes light bulbs provides information about some of their products.

The table shows some of this information.

Power in watts Lifetime in hours Cost of bulb in £

Filament bulb 60 1250 2.00

LED bulb 12 50 000 16.00

(i) Suggest why it is important to confirm this information independently.

______________________________________________________________ (1)

(ii) A homeowner is thinking about replacing his filament bulbs with LED bulbs.

A 12 W LED bulb gives the same light output as a 60 W filament bulb.

Suggest reasons why the homeowner is likely to choose LED bulbs.

Use the information given in the table.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________ (2)

(iii) State one factor, other than efficiency, that is important when considering the choice of a bulb for lighting in the home.

______________________________________________________________

of 62

______________________________________________________________ (1)

(Total 10 marks)

Q13. Electrical circuits have resistance.

(a) Draw a ring around the correct answer to complete the sentence.

When the resistance of a circuit increases, the current in the circuit

decreases.

increases.

stays the same.

(1)

(b) Use the correct answer from the box to complete each sentence.

a filament bulb an LED an LDR

An electrical component which has a resistance that increases as the

temperature increases is _________________________ .

An electrical component which emits light only when a current flows through it

in the forward direction is _________________________ . (2)

(c) When some metals are heated the resistance of the metal changes.

The equipment for investigating how the resistance of a metal changes when it is heated is shown in the diagram.

In this question you will be assessed on using good English, organising information

of 62

clearly and using specialist terms where appropriate.

Describe an investigation a student could do to find how the resistance of a metal sample varies with temperature. The student uses the equipment shown.

Include in your answer:

• how the student should use the equipment

• the measurements the student should make

• how the student should use these measurements to determine the resistance

• how to make sure the results are valid.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (6)

(d) The table shows some data for samples of four metals P, Q, R and S.

The metal samples all had the same cross-sectional area and were the same length.

Metal sample Resistance at Resistance at 100°C

of 62

0°C in ohms in ohms

P 4.05 5.67

Q 2.65 3.48

R 6.0 9.17

S 1.70 2.23

A graph of the results for one of the metal samples is shown.

Temperature in °C

(i) Which metal sample, P, Q, R or S, has the data shown in the graph? (1)

(ii) One of the results is anomalous. Circle this result on the graph. (1)

(iii) Suggest a reason for the anomalous result.

______________________________________________________________

______________________________________________________________ (1)

(iv) The same equipment used in the investigation could be used as a thermometer known as a ‘resistance thermometer.’

of 62

Suggest two disadvantages of using this equipment as a thermometer compared to a liquid-in-glass thermometer.

1. ____________________________________________________________

______________________________________________________________

2. ____________________________________________________________

______________________________________________________________ (2)

(Total 14 marks)

Q14. (a) The diagram shows the circuit used to obtain the data needed to plot the

current–potential difference graph for a filament bulb.

(i) Why is the component labelled ‘J’ included in the circuit?

______________________________________________________________

______________________________________________________________ (1)

(ii) The resistance of the bulb increases as the potential difference across the bulb

of 62

increases. Why?

______________________________________________________________

______________________________________________________________ (1)

(iii) The bulb is at full brightness when the potential difference across the bulb is 12 V. The current through the bulb is then 3 A.

Calculate the power of the bulb when it is at full brightness and give the unit.

______________________________________________________________

______________________________________________________________

______________________________________________________________

Power = _________________________ (3)

(b) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.

The table gives data about two types of light bulb people may use in their homes.

Type of light bulb

Energy efficiency

Cost of one light bulb

Average lifetime in

hours

Halogen 10% £1.95 2 000

Light Emitting Diode (LED) 32% £11.70 36 000

Both types of light bulb produce the same amount of light.

Evaluate, in terms of cost and energy efficiency, the use of the two types of light bulb.

To gain full marks you must compare both types of light bulb and conclude which light bulb would be the best to use.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

of 62

___________________________________________________________________

___________________________________________________________________ (6)

(Total 11 marks)

Q15. (a) The diagram shows the circuit used to investigate the resistance of a sample of a

material. The diagram is not complete; the ammeter and voltmeter are missing.

(i) Draw the symbols for the ammeter and voltmeter on the diagram in the correct places.

(2)

(ii) How can the current through the material be changed?

______________________________________________________________

______________________________________________________________ (1)

(b) The material, called conducting putty, is rolled into cylinders of different lengths but with equal thickness.

Graph 1 shows how the resistance changes with length.

of 62

Length in centimetres

(i) The current through a 25 cm length of conducting putty was 0.15 A.

Use Graph 1 to find the resistance of a 25 cm length of conducting putty.

Resistance = _________________________ ohms (1)

(ii) Use your answer to (b) (i) to calculate the potential difference across a 25 cm length of conducting putty.

Show clearly how you work out your answer.

______________________________________________________________

______________________________________________________________

______________________________________________________________

Potential difference = _________________________ volts (2)

(c) A second set of data was obtained using thicker pieces of conducting putty. Both sets of results are shown in Graph 2.

of 62

Length in centimetres

(i) What is the relationship between the resistance and the thickness of the conducting putty?

______________________________________________________________

______________________________________________________________ (1)

(ii) Name one error that may have reduced the accuracy of the results.

______________________________________________________________ (1)

(Total 8 marks)

Q16. The diagram shows how one type of electric storage heater is constructed. The heater has ceramic bricks inside. The electric elements heat the ceramic bricks during the night. Later, during the daytime, the ceramic bricks transfer the stored energy to the room.

of 62

(a) (i) Complete the following sentences using words from the box.

conduction convection evaporation

Energy is transferred through the metal casing by ___________________

The warm air rising from the heater transfers energy to the

room by ________________________ (2)

(ii) The inside of the metal case is insulated.

Which one of the following gives the reason why?

Tick ( ) one box.

To transfer energy from the ceramic bricks to the room faster

To stop energy from the room transferring into the heater

To keep the ceramic bricks hot for a longer time

(1)

(b) In winter, the electricity supply to a 2.6 kW storage heater is switched on for seven hours each day.

(i) Calculate the energy transferred, in kilowatt-hours, from the electricity supply to the heater in seven hours.


of 62

______________________________________________________________

______________________________________________________________

Energy transferred = _________________________ kWh (2)

(ii) The electricity supply to the heater is always switched on between midnight and 7 am. Between these hours, electricity costs 5 p per kilowatt-hour.

Calculate how much it costs to have the heater switched on between midnight and 7 am.

______________________________________________________________

______________________________________________________________

Cost = _________________________ p (1)

(c) Between 7 am and 8 am, after the electricity supply is switched off, the temperature of the ceramic bricks falls by 25 °C.

Calculate the energy transferred from the ceramic bricks between 7 am and 8 am.

Total mass of ceramic bricks = 120 kg. Specific heat capacity of the ceramic bricks = 750 J/kg °C.


___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Energy transferred = _________________________ J (2)

(Total 8 marks)

Q17. The data included in the diagrams gives the power of the electrical appliances.

TV Radiant heater Hairdryer

of 62

160 W 1.0 kW 1100 W

Sandwich toaster 1.1 kW

Food processor 0.4 kW

Table lamp 40 W

(a) (i) Which of the appliances are designed to transform electrical energy to kinetic energy?

______________________________________________________________

______________________________________________________________ (1)

(ii) Which of the appliances waste energy as heat?

______________________________________________________________

______________________________________________________________ (1)

(b) Leaving the radiant heater switched on is likely to lead to more carbon dioxide being emitted into the atmosphere than leaving the table lamp on for the same length of time.

Explain why.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (2)

(c) A homeowner decides to monitor the amount of electrical energy used in his home. He can do this by using the home’s electricity meter or by using a separate electronic device.

The table gives some information about each method.

Electricity meter Electronic device

Records to the nearest kilowatt-hour

Records to the nearest 1/100th kilowatt-hour

Homeowner takes Energy use recorded

of 62

readings at regular intervals

continuously and stored for one year

Displays a graph showing energy use over a period of time

(i) Complete the following sentence.

The reading given by the electronic device is more _____________________ than the reading given by the electricity meter.

(1)

(ii) Suggest how data collected and displayed by the electronic device could be useful to the homeowner.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________ (3)

(Total 8 marks)

Q18. The diagram shows the circuit set up by a student.

of 62

(a) The student uses the circuit to test the following hypothesis:

‘The current through a resistor is directly proportional to the potential difference across the resistor.’

(i) If the hypothesis is correct, what should the student predict will happen to the current through the resistor when the potential difference across the resistor is doubled?

______________________________________________________________

______________________________________________________________ (1)

(ii) Name the component in the circuit used to change the potential difference across the resistor.

______________________________________________________________ (1)

(b) The student used the data obtained to plot the points for a graph of current against potential difference.

(i) Why has the student plotted the points for a line graph and not drawn a bar chart?

______________________________________________________________

______________________________________________________________ (1)

(ii) One of the points has been identified by the student as being anomalous.

What is the most likely cause for this anomalous point?

______________________________________________________________

of 62

______________________________________________________________ (1)

(iii) Draw a line of best fit for these points. (1)

(iv) Does the data the student obtained support the hypothesis?


______________________________________________________________

______________________________________________________________ (1)

(Total 6 marks)

Q19. Diagram 1 shows a hairdryer. Diagram 2 shows how the heaters and fan of the hairdryer are connected to a 3-pin plug. The hairdryer does not have an earth wire.

(a) What colour is the insulation around the wire connected to the live pin inside the plug?

______________________________ (1)

(b) Why does the hairdryer not need an earth wire?

___________________________________________________________________

___________________________________________________________________ (1)

(c) All the switches are shown in the OFF position.

of 62

(i) Which switch or switches have to be ON to make:

(1) only the fan work; ____________________________________________

(2) heater 2 work? ______________________________________________ (2)

(ii) The heaters can only be switched on when the fan is also switched on.

Explain why.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________ (2)

(d) The table shows the current drawn from the 230 volt mains electricity supply when different parts of the hairdryer are switched on.

Current in amps

Fan only 1.0

Fan and heater 1 4.4

Fan and both heaters 6.5

Calculate the maximum power of the hairdryer.

Show clearly how you work out your answer and give the unit.

___________________________________________________________________

___________________________________________________________________

Maximum power = ______________________________ (3)

(Total 9 marks)

Q20. The diagram shows a simple type of car rear window heater. The six heating elements are exactly the same.

of 62

Each heating element has a resistance of 5 Ω. The current passing through each element is 0.4 A.

(i) Calculate the total resistance of the six heating elements.


___________________________________________________________________

___________________________________________________________________

Total resistance = _______________ ohms (2)

(ii) Why is the current passing through each element the same?

___________________________________________________________________

___________________________________________________________________ (1)

(iii) What is the total current passing through the whole circuit?

___________________________________________________________________ (1)

(iv) How is the 12 volt potential difference of the car battery shared between the six heating elements?

___________________________________________________________________

___________________________________________________________________ (1)

(Total 5 marks)

Q21. (a) The diagram shows the circuit used to investigate the resistance of a material. The

diagram is incomplete; the ammeter and voltmeter are missing.

of 62

(i) Draw the symbols for the ammeter and voltmeter on the diagram in the correct places.

(2)

(ii) How can the current through the material be changed?

______________________________________________________________

______________________________________________________________ (1)

(b) The material, called conducting putty, is rolled into cylinders of different lengths but with equal thicknesses.

Graph 1 shows how the resistance changes with length.

Graph 1

(i) Why has the data been shown as a line graph rather than a bar chart?

______________________________________________________________

______________________________________________________________ (1)

(ii) The current through a 30 cm length of conducting putty was 0.15 A.

of 62

Use Graph 1 to find the resistance of a 30 cm length of conducting putty.

Resistance = ________________________ ohms (1)

(iii) Use your answer to (b)(ii) to calculate the potential difference across a 30 cm length of conducting putty.


______________________________________________________________

______________________________________________________________

______________________________________________________________

Potential difference = ________________________ volts (2)

(c) A second set of data was obtained using thicker pieces of conducting putty. Both sets of results are shown in Graph 2.

Graph 2

(i) What is the relationship between the resistance and the thickness of the conducting putty?

______________________________________________________________

______________________________________________________________ (1)

(ii) Name one error that may have reduced the accuracy of the results.

of 62

______________________________________________________________ (1)

(iii) How could the reliability of the data have been improved?

______________________________________________________________

______________________________________________________________ (1)

(Total 10 marks)

Q22. (a) The circuit diagram drawn below includes a component labelled X.

(i) Calculate the potential difference across the 8 ohm resistor.


______________________________________________________________

______________________________________________________________

Potential difference = _________________________ volts (2)

(ii) What is the potential difference across component X?

______________________________________________________________ (1)

(b) The graph shows how the resistance of component X changes with temperature.

of 62

(i) What is component X?

______________________________________________________________ (1)

(ii) Over which range of temperatures does the resistance of component X change the most?

Put a tick ( ) next to your choice.

0 °C to 20 °C

20 °C to 40 °C

40 °C to 60 °C

60 °C to 80 °C

80 °C to 100 °C

(1) (Total 5 marks)

Q23. The drawing shows the circuit used to investigate how the current through a 5 ohm (Ω) resistor changes as the potential difference (voltage) across the resistor changes.

of 62

(a) Draw, in the space below, a circuit diagram of this circuit. Use the correct symbols for each part of the circuit.

(2)

(b) (i) Write down the equation that links current, potential difference and resistance.

______________________________________________________________ (1)

(ii) Calculate the potential difference across the 5 ohm (Ω) resistor when the current through the resistor equals 0.4 A. Show clearly how you work out your final answer.

______________________________________________________________

______________________________________________________________

potential difference = _______________________ volts

of 62

(2)

(iii) Complete the graph to show how the current through the resistor changes as the potential difference across the resistor increases from 0 V to 3 V. Assume the resistor stays at a constant temperature.

(2)

(c) The resistor is replaced by a 3 V filament lamp. The resistance of the lamp increases as the potential difference across it increases. Why?

___________________________________________________________________

___________________________________________________________________ (1)

(Total 8 marks)

Q24. The circuit shown has four identical ammeters.

(a) The table gives the current through two of the ammeters.

of 62

(i) Complete the table to show the current through the other two ammeters.

Ammeter Reading on ammeter in amps

A1

A2 0.2

A3 0.3

A4

(2)

(ii) Which one of the following statements is correct. Tick ( ) the box next to your choice.

The resistance of P is more than 20 Ω.

The resistance of P is equal to 20 Ω.

The resistance of P is less than 20 Ω.

Give a reason for your choice.

______________________________________________________________

______________________________________________________________

______________________________________________________________ (2)

(b) (i) Write down the equation that links current, potential difference and resistance.

______________________________________________________________ (1)

(ii) Calculate the reading on the voltmeter. Show clearly how you work out your answer.

______________________________________________________________

______________________________________________________________

Voltmeter reading = _______________ volts. (2)

(iii) State the potential difference of the power supply.

______________________________________________________________ (1)

(c) A second circuit contains an unknown component labelled X.

of 62

As component X is heated, the reading on the ammeter goes up.

What is component X?

___________________________________________________________________


___________________________________________________________________

___________________________________________________________________ (2)

(Total 10 marks)

Q25. (a) The diagram shows the voltage-current graphs for three different electrical

components.

Which one of the components A, B or C could be a 3 volt filament lamp? Explain the reason for your choice.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (3)

(b) Using the correct symbols draw a circuit diagram to show how a battery, ammeter and voltmeter can be used to find the resistance of the wire shown.

of 62

(3)

(c) When correctly connected to a 9 volt battery the wire has a current of 0.30 amperes flowing through it.

(i) Give the equation that links current, resistance and voltage.

______________________________________________________________ (1)

(ii) Calculate the resistance of the wire. Show clearly how you work out your answer and give the unit.

______________________________________________________________

______________________________________________________________

Resistance = _____________________________ (3)

(iii) When the wire is heated, the current goes down to 0.26 amperes. State how the resistance of the wire has changed.

______________________________________________________________

______________________________________________________________ (1)

(Total 11 marks)

Q26. Some students want to find out how the current through component X changes with the voltage they use.

The diagram shows their circuit. The graph shows their results.

(a) Describe, as fully as you can, what happens to the current through component X as

of 62

the students increase the voltage.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (4)

(b) The students want to find out whether component X allows the same current to flow through it in the opposite direction.

(i) How should they change the circuit to test this?

______________________________________________________________ (1)

(ii) The graph shows the students’ extra results.

What do the extra results tell you?

______________________________________________________________

______________________________________________________________

______________________________________________________________ (1)

(Total 6 marks)

Q27. (a) Add the missing labels to the diagram.

of 62

(3)

(b) Some students use the circuit shown above.

They want to find out how the current through component X changes as they change the voltage.

The graph shows their results.

Describe, as fully as you can, what happens to the current through component X as the students increase the voltage.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (4)

(Total 7 marks)

Q28. A computer is set up to produce a graph of the current through an electric lamp during the first few milliseconds after it is switched on.

of 62

The lamp is modified then tested in the same way.

(a) Describe three differences in the way the lamp behaves after it has been modified.

1. _________________________________________________________________

2. _________________________________________________________________

3. _________________________________________________________________ (3)

(b) The current through the modified lamp depends on the total resistance of the filament and component X.

The smaller this total resistance is, the greater the current.

The following graphs show how the resistance of the lamp filament and component X change as the lamp heats up to its operating temperature.

of 62

Use the information shown on the graphs to explain the behaviour of the modified lamp.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (4)

(Total 7 marks)

Q29. Some electronic calculators use light emitting diodes (LEDs) to display numbers. Each number in a display consists of up to seven LEDs. The LEDs are arranged as shown in the diagram below. The different numbers are formed by switching different LEDs on at the same time. The LEDs are labelled A to G.

A simplified circuit to provide power to the LEDs is shown below.

of 62

(a) Explain why each LED has its own switch.

___________________________________________________________________

___________________________________________________________________ (2)

(b) What number is displayed when all switches except E are closed?

___________________________________________________________________ (1)

(c) Which switches would be open if the number 3 is to be displayed?

___________________________________________________________________ (1)

(d) Which of the numbers 0 to 9 draws least current from the battery? Explain your answer.

Number ________________________

Explanation _________________________________________________________

___________________________________________________________________

___________________________________________________________________ (2)

(Total 6 marks)

Q30. The circuit diagram below shows a battery connected to a lamp and a switch.

of 62

(a) State what happens to the lamp when:

(i) the switch is open (OFF);

______________________________________________________________

(ii) the switch is closed (ON).

______________________________________________________________ (2)

(b) When the switch is closed what problem is caused in the circuit?

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (1)

(c) In the space below draw a circuit diagram to show how the switch should be correctly connected to the lamp and battery.

(1)

(Total 4 marks)

Q31. A student investigates how the current flowing through a filament lamp changes with the voltage across it. She is given a filament lamp and connecting wires. She decides to use a 15V power supply, a variable resistor, an ammeter, a voltmeter and a switch.

(a) Complete the circuit diagram to show how she should set up the circuit.

of 62

(4)

(b) The student obtains the following results.

VOLTAGE (V) 0.0 3.0 5.0 7.0 9.0 11.0

CURRENT (A) 0.0 1.0 1.4 1.7 1.9 2.1

(i) Plot a graph of current against voltage.

(3)

(ii) Use your graph to find the current when the voltage is 10V.

Current __________ A (1)

(iii) Use your answer to (ii) to calculate the resistance of the lamp when the voltage is 10V.

______________________________________________________________

of 62

______________________________________________________________

______________________________________________________________

Resistance __________ Ω (2)

(c) (i) What happens to the resistance of the lamp as the current through it increases?

______________________________________________________________

(ii) Explain your answer.

______________________________________________________________

______________________________________________________________

______________________________________________________________ (2)

(Total 12 marks)

Q32. A bulb heats up when an electric current passes through the filament wire. The current was measured when different voltages were applied across the filament wire shown in the diagram below.

(a) (i) Look at the circuit diagram. How was the voltage changed?

______________________________________________________________

______________________________________________________________ (1)

(ii) Write an equation that shows the relationship between current, potential difference and resistance.

______________________________________________________________ (1)

(b) The graph shows how the current through the filament wire changed as the potential difference across it changed.

of 62

(i) Describe the effect of increasing the potential difference on the current flowing through the filament wire.

______________________________________________________________

______________________________________________________________

______________________________________________________________ (2)

(ii) Explain this effect in terms of the resistance of the filament wire.

______________________________________________________________

______________________________________________________________

______________________________________________________________ (2)

(Total 6 marks)

Q33. The current through component X is measured when different voltages are applied across it.

of 62

(a) Name the component labelled Y in the circuit.

___________________________________________________________________ (1)

(b) What type of meter is Z?

___________________________________________________________________ (1)

(c) The table shows the measurements obtained in this experiment.

Voltage in V 0 0.2 0.4 0.6 0.8

Current in mA 0 0 50 100 150

Draw a graph of the measurements.

(2)

(d) Use the shape of the graph to name component X.

___________________________________________________________________ (1)

(Total 5 marks)

Q34. A circuit was set up as shown in the diagram.

of 62

(a) The table gives the current through three of the ammeters. Complete the table to show the current through the other two ammeters.


Al 0.2

A2 0.6

A3 0.3

A4

A5

(2)

(b) The reading on the voltmeter is 12 V.

What is the resistance of R2?

Show your working and include the correct unit.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Resistance = ____________________ (3)

(c) In the circuit above, the resistor R2 burned out and current stopped flowing in it.

of 62

There was no other change to the circuit.

Complete the table below to show the readings on the ammeters after this took place.


Al 0.2

A2 0.0

A3

A4

A5

(3) (Total 8 marks)

Q35. The diagram shows an electronic circuit.

(a) Write down the names of the components in the list below.

A = _____________________________________________

B = _____________________________________________

C = _____________________________________________

D = _____________________________________________

E, F and G = _____________________________________________ (5)

(b) The graph shows how the resistance of component B depends on its temperature.

of 62

Describe, in as much detail as you can, how the resistance of component B changes as its temperature rises from 0ºC to 80ºC.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________ (4)

(c) At what temperature does component B have a resistance of 1000 ohms?

Answer _____________________ °C . (2)

(Total 11 marks)

2.1 electricity - standard demand - qs · use your knowledge of energy sources as well as...

Documents