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Physics GCSE AQA, Unit 2:Electricity 1 1 Q1. A small torch uses a single cell to make the bulb light up. (a) The graphs show the voltage across two different types of cell as they transfer the last bit of their stored energy through the torch bulb. Describe the differences that the graphs show between the two types of cell. ..................................................................................................................................... ..................................................................................................................................... (3) (b) The diagram shows how bright the torch bulb is for different voltages. From the point when the voltage of each cell starts to fall, how long will the bulb stay lit: (i) with the ordinary cell? ........................................................................................................................... (ii) with the nicad cell? ........................................................................................................................... (4) (c) When the voltage across the bulb falls to half, the current through the bulb falls by less than half. Why is this? ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... (3) (Total 10 marks)

AQA P2 Electricity

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Page 1: AQA P2 Electricity

Physics GCSE AQA, Unit 2:Electricity 1

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Q1. A small torch uses a single cell to make the bulb light up.

(a) The graphs show the voltage across two different types of cell as they transfer the last bit of their stored energy through the torch bulb.

Describe the differences that the graphs show between the two types of cell.

.....................................................................................................................................

..................................................................................................................................... (3)

(b) The diagram shows how bright the torch bulb is for different voltages.

From the point when the voltage of each cell starts to fall, how long will the bulb stay lit:

(i) with the ordinary cell?

...........................................................................................................................

(ii) with the nicad cell?

........................................................................................................................... (4)

(c) When the voltage across the bulb falls to half, the current through the bulb falls by less than half. Why is this?

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(Total 10 marks)

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Q2. A small torch uses a single cell to make the bulb light up.

(a) Label the symbol for a cell and the symbol for a bulb (lamp)

(2)

(b) The graphs show the voltage across two different types of cell as they transfer the last bit of their stored energy through the torch bulb.

Describe the differences that the graphs show between the two types of cell.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(c) The diagram shows how bright the torch bulb is for different voltages.

From the point when the voltage of each cell starts to fall, how long will the bulb stay lit:

(i) with the ordinary cell?

..........................................................................................................................

(ii) with the nicad cell?

.......................................................................................................................... (4)

(Total 9 marks)

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Q4. 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 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)

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Q5. (a) Add the missing labels to the diagram.

(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)

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Q3. The diagram shows an electrical circuit.

(a) Complete the two labels on the diagram. (2)

(b) P and Q are meters.

What is meter P measuring? .......................................................................................

What is meter Q measuring? ....................................................................................... (2)

(Total 4 marks)

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Q7. 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.

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.

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

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (4)

(Total 7 marks)

Q6. Label the parts of the electric circuit below.

(Total 3 marks)

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Q8. 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.

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

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

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(4)

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

Answer ......................................... °C . (2)

(Total 11 marks)

Q10. The drawing shows a food processor. It has an electric motor. Inside is a blade which spins round and cuts up the food.

The food processor is designed to transfer electrical energy to kinetic energy. However some of the energy is wasted as heat and sound.

The power input to the food processor is 1150 W. The power of the spinning blade is 900 W.

(i) Calculate how much energy is wasted when the food processor is used for two minutes.

Show clearly how you get to your answer and give the unit.

power =

.....................................................................................................................................

.....................................................................................................................................

Energy = ......................................................... (3)

(ii) Why does the food processor produce sound when it is switched on?

.....................................................................................................................................

..................................................................................................................................... (1)

(Total 4 marks)

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Q9. Carefully read the following extract from a safety leaflet. Then answer the questions.

An RCD adaptor is an automatic safety switch. It should be used when there is a particular risk of electric shock. For example, it is recommended that it is used with an electric lawnmower.

Inside one make of RCD is an electromagnet that holds the switch closed so that the RCD is switched on. An electronic circuit in the RCD monitors the difference between the current in the live wire and the current in the neutral wire.

If something goes wrong and this difference is greater than 30 milliamps then the RCD will trip (= switch off) within 40 milliseconds.

(a) Suggest two reasons why there is a particular risk of an electric shock when using an electric lawnmower.

1. ................................................................................................................................

.....................................................................................................................................

2. .................................................................................................................................

..................................................................................................................................... (2)

(b) Why will there be a difference between the current in the live wire and the current in the neutral wire if something goes wrong?

.....................................................................................................................................

..................................................................................................................................... (1)

(c) (i) Use the words charge, current and time to write an equation which shows the relationship between them.

.......................................................................................................................... (1)

(ii) Calculate how much charge flows when a current of 30 milliamps passes for 40 milliseconds.

Clearly show how you get to your answer and give the unit.

..........................................................................................................................

..........................................................................................................................

Charge = ..................................................... (3)

(Total 7 marks)

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Q11. A combination oven can cook food by using three methods; a microwave generator, a grill and a heating element.

voltage 230 V microwave power (max) 900 W

grill power 1300 W convection heater power 1200 W

(a) What is the current when the oven is operating using full microwave power? Give the equation and show your working.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

Current = ................................................... A (3)

(b) It is possible to cook using infrared radiation, from the grill, and microwaves. What is the maximum current in the oven when using both together?

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

Current = ................................................... A (2)

(c) For baking and roasting, the microwave is used at 450 W and the convection heating element is on fully at 1200 W. A thawed or fresh medium-sized chicken takes 30 minutes to cook.

Calculate the energy transferred in kilowatt-hours.

Use:

units (kWh) = power (kW) × time (h)

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

Energy = .................................................... kWh (2)

(d) Why is a combination oven of this sort more economical than a convection-only oven?

.....................................................................................................................................

..................................................................................................................................... (1)

(Total 8 marks)

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Q12. The diagram shows the inside of a mains plug.

(a) Label the earth, live and neutral pins.

(3)

(b) (i) Explain how the earth wire and the fuse protect a person from an electric shock when there is a short circuit to the metal case of an appliance.

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (4)

(ii) What is the most appropriate size fuse rating for a fuse in a television?

Circle the correct answer.

3 A 5 A 13 A (1)

(Total 8 marks)

Q13. The circuit contains two cells, an ammeter and a lamp. The reading on the ammeter is 0.2 A.

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(a) What will be the reading on the ammeters in each of the circuits below?

(i) Current is ................... A (ii) Current is ................... A (2)

(b) An ammeter was in a series circuit with two cells and a variable resistor.

The ammeter showed a reading of 0.3 A.

(i) Draw a circuit diagram for the circuit.

(2)

(ii) What will happen to the reading on the ammeter if the resistance of the variable resistor is increased?

.......................................................................................................................... (1)

(Total 5 marks)

Q14. The diagram shows a type of electric immersion heater in a hot water tank. These hot water tanks are normally found in airing cupboards.

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Information on the immersion heater states:

230 V, 10 A

(a) (i) What is the equation which shows the relationship between power, current and voltage?

.......................................................................................................................... (1)

(ii) Calculate the power of the heater. Show clearly how you get to your answer and give the units.

..........................................................................................................................

Power = ...................................................... (2)

(b) (i) What rating of fuse should be in the immersion heater circuit?

.......................................................................................................................... (1)

(ii) There are three wires in the cable to the immersion heater. Two of the wires are connected to the immersion heater. The third wire is connected to the copper tank.

Explain the function of this third wire and the fuse in the circuit.

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (3)

(c) (i) What is the equation which shows the relationship between resistance, current and voltage?

.......................................................................................................................... (1)

(ii) Calculate the resistance of the heater. Show clearly how you get to your answer and give the units.

..........................................................................................................................

Resistance = .................................................... (2)

(Total 10 marks)

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Q15. The drawing shows a 230 V electric light bulb.

The filament is made of high-resistance wire. The connecting wires in the light bulb have a low resistance.

(a) The light bulb is switched on. Explain what happens when there is current in the filament.

....................................................................................................................................

.................................................................................................................................... (2)

(b) Why must the connecting wires have a low resistance?

.................................................................................................................................... (1)

(c) State two properties of glass that make it a good material to support the connecting wires.

Choose your answers from the words in the box.

conductor insulator opaque soft

strong transparent weak

............................................................... and ............................................................. (2)

(Total 5 marks)

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Q16. In a hairdryer circuit there is a heater and a motor. It is important that the motor is always running when the heater is switched on.

(a) Using the symbols shown below only once each, draw a circuit for a hairdryer.

(2)

(b) Modern hairdryers are described as double insulated.

Explain what this term means.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(c) On a modern hairdryer handle it states:

1600 W 230 V 50 Hz

(i) [A] Write an equation which shows the relationship between current, power and voltage.

................................................................................................................ (1)

[B] Calculate the current in the hairdryer when it is on full power. Show clearly how you get your answer.

................................................................................................................

................................................................................................................

Current = ........................... A (2)

(ii) [A] Write an equation which shows the relationship between current, resistance and voltage.

................................................................................................................ (1)

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[B] The resistance of the heater is 20 ohms. Calculate the resistance of the motor.

Show clearly how you get your answer.

................................................................................................................

................................................................................................................

Resistance = ............... ohms (2)

(Total 10 marks)

Q17. The circuit contains three identical lamps.

(a) Complete each of the sentences about the circuit, using one of the phrases in the box.

more than less than the same as

(i) The current at A is ........................................................... .the current at B. (1)

(ii) The current at A is ........................................................... .the current at D. (1)

(iii) The current at F is ............................................................. .the current at E. (1)

(iv) The current at F is ............................................................ .the current at D. (1)

(b) In the circuit, which lamp is brightest?.............................

Give a reason for your answer.

....................................................................................................................................

.................................................................................................................................... (2)

(Total 6 marks)

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Q18. The drawing shows an experiment using a low voltage supply, a joulemeter, a small immersion heater and a container filled with water.

The voltage was set at 6 V d.c. The reading on the joulemeter at the start of the experiment was 78 882 and 5 minutes later it was 80 142.

(i) Use the equation:

voltage =

to work out the total charge which flowed through the immersion heater in five minutes. Clearly show how you get to your answer and give the unit.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

Charge = ............................................ (3)

(ii) Calculate the current through the immersion heater during the 5 minutes. Write the equation you are going to use, show clearly how you get to your answer and give the unit.

.....................................................................................................................................

.....................................................................................................................................

Current = ......................................... (3)

(Total 6 marks)

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Q19. A student did an experiment with two strips of polythene. She held the strips together at one end. She rubbed down one strip with a dry cloth. Then she rubbed down the other strip with the dry cloth. Still holding the top ends together, she held up the strips.

(a) (i) What movement would you expect to see?

...........................................................................................................................

........................................................................................................................... (1)

(ii) Why do the strips move in this way?

........................................................................................................................... (2)

(b) Complete the four spaces in the passage.

Each strip has a negative charge. The cloth is left with a............................................

charge. This is because particles called .................................. have been transferred

from the .................................... to the ........................................ . (4)

(c) The student tried the experiment using two strips of aluminium. The strips did not move.

Complete each of the sentences.

(i) Materials, such as aluminium, which electricity will pass through easily, are

called ........................................ . (1)

(ii) Materials, such as polythene which electricity will not pass through easily, are

called ......................................... . (1)

(Total 9 marks)

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Q20. A circuit was set up as shown in the diagram.

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

Ammeter Reading on ammeter in amps

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)

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(c) In the circuit above, the resistor R2 burned out and current stopped flowing in it. There was no other change to the circuit.

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

Ammeter Reading on ammeter in amps

Al 0.2

A2 0.0

A3

A4

A5

(3)

(Total 8 marks)

Q22. (a) The diagram shows a simple circuit. Add an ammeter and a voltmeter to the circuit to show how to measure the current through the fixed resistor and the voltage across it.

(2)

(b) An experiment using a circuit like the one above was set up. The following results were obtained when the resistance of the variable resistor was decreased.

(i) Draw a graph of the results below.

Voltage across fixed resistor in volts

Current in amps

0.50 0.75 1.00 1.25

0.10 0.15 0.20 0.25

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(2)

(ii) Use the graph to find the voltage when the current is 0.05 A.

Voltage =....................................... V (1)

(Total 5 marks)

Q21. (i) Write the equation which shows the relationship between the electric current, the power and the voltage.

.....................................................................................................................................

..................................................................................................................................... (1)

(ii) Calculate the power if the current is 5 A and the voltage is 400 000 V. Show clearly how you work out your answer and give the unit.

.....................................................................................................................................

.....................................................................................................................................

Power = ............................................. (2)

(Total 3 marks)

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Q23. The diagram shows the fuel gauge assembly in a car.

• The sliding contact touches a coil of wire and moves over it.

• The sliding contact and the coil form a variable resistor.

• The sliding contact is connected to a float via a pivot.

• The fuel gauge indicator is an ammeter.

• When the petrol level changes, the resistance of the circuit changes.

• This causes the pointer in the fuel gauge indicator to move.

(a) Use standard symbols to draw a circuit diagram for the fuel gauge assembly.

(3)

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(b) How will the current in the circuit change as the level of petrol in the tank falls?

.....................................................................................................................................

Explain the reason for your answer.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 5 marks)

Q24. The current through component X is measured when different voltages are applied across it.

(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.

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(2)

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

..................................................................................................................................... (1)

(Total 5 marks)

Q25. The diagram shows a circuit.

(a) (i) Name component X. .........................................................

(ii) What does meter Y measure? ...........................................

(iii) What does meter Z measure? ........................................... (3)

(b) Which of the equations shows how current, potential difference and resistance are related?

Tick the box against the correct equation.

current = potential difference × resistance

potential difference = current × resistance

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resistance = current × potential difference (1)

(Total 4 marks)

Q26. 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.

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(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)

Q27. 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.

(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.

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(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.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

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)

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Q28. The diagram shows the inside of a 3-pin plug.

(a) What colour wire should be connected to each terminal?

Terminal E .........................................................................

Terminal N .........................................................................

Terminal L ......................................................................... (3)

(b) Name two parts inside the 3-pin plug which help to make it safe.

1 .................................................................................................................................

....................................................................................................................................

2 .................................................................................................................................

.................................................................................................................................... (2)

(Total 5 marks)

Q29. (a) The diagram shows a fan heater.

(i) A current of 11A flows when the fan heater is working normally. Fuses of value 3A, 5A, 10A and 13A are available. Which one should be used in the plug of the fan heater?

................................... (1)

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(ii) A fault caused a much higher than normal current to flow in the heater. Describe what happened to the wire in the fuse.

............................................................................................................................

............................................................................................................................

............................................................................................................................

............................................................................................................................ (2)

(b)

You may find this equation useful when answering this part of the question

energy transferred (kWh) = power (kilowatt, kW) × time (hour, h)

(i) The power of the fan heater is 2.75 kW. Calculate how many kilowatt hours of energy are transferred when the fan heater is used for 6 hours.

............................................................................................................................

............................................................................................................................

............................................................................................................................

Number of kilowatt hours ........................ (2)

(ii) How much will it cost to use the fan heater for 6 hours if one Unit of electricity costs 7p?

............................................................................................................................

............................................................................................................................

Cost ..................... p (2)

(Total 7 marks)

Q31. The diagram shows a fan heater.

(a) Complete this sentence.

The fan heater is designed to transfer electrical energy as ........................................

energy and ........................................ energy.

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(2)

(b) The fan heater is connected to the mains by a three core cable.

(i) Why are the wires in the cable made out of copper?

............................................................................................................................

(ii) Why are the wires in the cable covered by plastic?

............................................................................................................................ (2)

(c)

You may find this equation useful when answering this part of the question

energy transferred (kWh) = power (kilowatt, kW) × time (hour, h)

(i) The power of the fan heater is 2.75 kW. Calculate how many kilowatt hours (kWh) of energy are transferred when the fan heater is used for 6 hours.

............................................................................................................................

............................................................................................................................

Number of kilowatt hours ......................... (2)

(ii) How much will it cost to use the fan heater for 6 hours if one Unit of electricity costs 7p?

............................................................................................................................

............................................................................................................................

Cost ..................... p (2)

(d) A fault caused a much higher than normal current to flow in the heater. Describe what happened to the wire in the fuse.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(Total 10 marks)

Q30. (a) Complete the sentence below to name the instrument used to measure electrical current.

The instrument used to measure electrical current is called ...................................... (1)

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(b) In the diagram below each box contains an electrical component or a circuit symbol. Draw straight lines to link each electrical component to its circuit symbol. The first one has been done for you.

(4)

(Total 5 marks)

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Q32. The circuit diagram below shows a battery connected to a lamp and a switch.

(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)

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Q33. The diagrams show a hair-dryer and the circuit inside the hair-dryer.

(a) Switches S1, S2 and S3 are all shown in the OFF position.

Which switch or switches have to be ON to make:

(i) only the fan work? ............................................................................................

(ii) both heaters work? ............................................................................................ (2)

(b) (i) What happens to the current in the circuit when the heaters are switched on?

...........................................................................................................................

(ii) Suggest why it is important to have the fan working when the heaters are switched on.

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (3)

(c) This hair-dryer has a plastic case. It is connected to a mains socket by a 3-pin plug. The cable connecting the hair-dryer to the plug contains only two wires.

(i) Write down the colour of the insulation on the wires.

Wire 1 ...............................................................................................................

Wire 2 ...............................................................................................................

(ii) Which of the usual three wires is not needed?

...........................................................................................................................

(iii) This hair-dryer is safe to use without the third wire. Explain why.

...........................................................................................................................

...........................................................................................................................

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........................................................................................................................... (5)

(d) The following information is stamped on the hair-dryer.

(i) Which number tells us how fast the hair-dryer uses energy?

...........................................................................................................................

(ii) On what else does the energy used by the hair-dryer depend?

........................................................................................................................... (2)

(Total 12 marks)

Q34. A pupil did an experiment following the instructions below.

1. Take a polythene rod (AB), hold it at its centre and rub both ends with a cloth.

2. Suspend the rod, without touching the ends, from a stand using a stirrup and nylon thread.

3. Take a perspex rod (CD) and rub it with another cloth.

4. Without touching the ends of the perspex rod bring each end of the perspex rod up to, but without touching, each end of the polythene rod.

5. Make notes on what is observed.

The diagram below shows how the apparatus is to be set up.

(a) When end C was brought near to end B they attracted each other.

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(i) Explain why they attracted each other.

.........................................................................................................................

.........................................................................................................................

(ii) What would happen if end C were brought near end A?

......................................................................................................................... (3)

(b) The experiment was repeated with two polythene rods.

(i) Describe what you would expect the pupil to observe as the end of one rod was brought near to the end of the other.

.........................................................................................................................

.........................................................................................................................

(ii) Explain your answer.

.........................................................................................................................

......................................................................................................................... (2)

(c) Explain, in terms of electron movement, what happened as the rods were rubbed with the cloths.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

................................................................................................................................... (3)

(Total 8 marks)

Q35. 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.

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

(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)

Q36. You wash and dry your hair, then comb it with a plastic comb. As you move the comb away from your head some hairs are attracted to the comb.

(a) What has happened to the comb to make it attract the hairs?

.....................................................................................................................................

..................................................................................................................................... (1)

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(b) If the comb is now held above some small pieces of dry tissue paper what is likely to happen?

.....................................................................................................................................

..................................................................................................................................... (1)

(c) If you rub your hands all over the comb it will no longer attract your hair. Explain why.

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 4 marks)

Q37. (a) The diagram below shows the three pins in a mains plug. The pins connect with the live, neutral and earth terminals in a socket.

On the diagram, label each pin to show which is:

the live pin,

the neutral pin,

the earth pin. (3)

(b) The diagram below shows the inside of a mains plug.

(i) Name one material which could be used for the part labelled X.

..........................................................................................................................

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(ii) Complete the sentences below.

The part labelled Y is called the ................................................................... .

This is used to hold the ........................................................ firmly in place.

The component labelled Z is the .................................................................. .

(iii) The plug is used with an electric fire. Which part of the electric fire is connected to the earth pin?

.......................................................................................................................... (5)

(Total 8 marks)

Q38. When a mains lamp is switched on it takes 0.5 seconds for the filament to reach its normal operating temperature. The way in which the current changes during the first second after switching on is shown in the sketch graph below. Mains voltage is 240 V.

(a) Calculate the resistance of the filament whilst the lamp is drawing the maximum current.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (3)

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(b) Describe how the resistance of the lamp changes after the current has reached its maximum value.

....................................................................................................................................

.................................................................................................................................... (2)

(c) Calculate the maximum power taken by the lamp.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(d) Calculate the power of the lamp in normal use.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(e) Calculate the energy used by the lamp in six hours of normal use.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (3)

(Total 12 marks)

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Q39. (a) The picture below shows the bathroom in a house.

Describe three examples of dangerous practice in the use of mains electricity in this bathroom.

1. ................................................................................................................................

....................................................................................................................................

2. ................................................................................................................................

....................................................................................................................................

3. ................................................................................................................................

.................................................................................................................................... (3)

(b) In the table below three electrical appliances are listed with their power ratings and the number of hours they are used each week.

ELECTRICAL APPLIANCE

POWER RATINGS

(W)

TIME USED EACH WEEK

(h)

k Wh USED EACH WEEK

TV 200 35

Kettle 2000 2

Toaster 1000 1

Cooker 11 500 7

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(i) Complete the table by inserting the number of kWh used by each appliance each week.

(ii) Which appliance would cost the least to run per week?

..........................................................................................................................

(iii) The cost of running a toaster is 8p per week. How much does it cost to run the kettle each week?

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (6)

(Total 9 marks)

Q40. The circuit diagram below shows a circuit used to supply electrical energy to the two headlights of a car.

The current through the filament of one car headlight is 3.0 A. The potential difference across each of the two headlights is 12 V.

(a) Suggest a suitable fuse for the circuit. .............................................. (1)

(b) Calculate the resistance of the headlight filament when in use.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

Answer ............................. Ω (2)

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(c) Calculate the power supplied to the two headlights of the car.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

Answer ............................ W (2)

(d) The fully charged car battery can deliver 72 kJ of energy at 12 V. How long can the battery keep the headlights fully on?

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

Answer .............................. s (2)

(Total 7 marks)

Q41. The diagram below shows how one type of fuel gauge in a car works. A sliding contact makes contact with a resistance wire wound in a coil (rheostat). It is connected to a float via a pivot P. When the petrol level changes the circuit resistance changes. This causes the pointer in the fuel gauge to move and show how much petrol is in the petrol tank.

The circuit diagram is shown below.

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The petrol gauge is an ammeter. Explain why the reading on the ammeter falls as the petrol is used.

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

............................................................................................................................................... (Total 3 marks)

Q42. The diagram below shows an electric mains plug.

(a) Name the parts of the plug labelled A and B.

A .....................................................................................

B ..................................................................................... (2)

(b) Name the colour of each of the wires X, Y and Z.

X .....................................................................................

Y .....................................................................................

Z ..................................................................................... (3)

(c) Name a suitable material for the case of the plug.

..................................................................................................................................... (1)

(d) Electric fires have three wires connected in the plug. One is the live wire to feed electric current in, another is the neutral (return) wire.

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(i) What is the third wire called?

........................................................................................................................... (1)

(ii) Why is it important that the third wire is also connected?

...........................................................................................................................

........................................................................................................................... (1)

(e) The diagram below shows a badly wired mains plug.

Look at the plug carefully. What four changes should be made to make the plug safe?

1. ...............................................................................................................................

........................................................................................................................………

2. ...............................................................................................................................

........................................................................................................................………

3. ...............................................................................................................................

........................................................................................................................………

4. ...............................................................................................................................

.................................................................................................................................... (4)

(Total 12 marks)

Q43. The table contains typical data for an oil tanker.

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(i) Write down the equation which links acceleration, force and mass.

..................................................................................................................................... (1)

(ii) Calculate the deceleration of the oil tanker. Show clearly how you work out your answer.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

Deceleration = ............................ m/s2 (2)

(Total 3 marks)

Q44. (a) An adaptor can be used to connect up to four appliances in parallel to one 230 V mains socket. The adaptor is fitted with a 13 A fuse. The table gives a list of appliances and the current they draw from a mains socket.

Appliance Current

computer 1 A

hairdryer 4 A

heater 8 A

iron 6 A

television 2 A

(i) What current will flow to the adaptor when the television, computer and hairdryer are plugged into the adaptor?

..........................................................................................................................

Current = .................................. A (1)

(ii) Write down the equation which links current, electrical power and voltage.

....................................................................................................................... (1)

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(iii) Calculate the electrical power used when the television, computer and hairdryer are plugged into the adaptor. Show clearly how you work out your answer and give the unit.

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

Electrical power = ...................................... (2)

(iv) What would happen to the fuse if the heater is also plugged into the adaptor?

Give a reason for your answer.

..........................................................................................................................

.......................................................................................................................... (2)

(b) The diagram shows two of the appliances.

(i) For safety reasons, it is important that the iron has an earth wire connected to its outer metal case. Explain why.

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(ii) The hairdryer does not have an earth wire. It is safe to use because it is double insulated. Explain what the term double insulated means.

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(Total 10 marks)

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Q45. (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.

(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)

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Q46. (a) The diagram shows an electric fence, designed to keep horses in a field.

When a horse touches the wire the horse receives a mild electric shock. Explain how.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(b) The diagram shows how a person could receive an electric shock from a faulty electrical appliance. Using a residual circuit breaker (RCB) can help to protect the person against receiving a serious shock.

Current

to earth

(i) Compare the action of an RCB to that of a fuse.

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(ii) The graph illustrates how the severity of an electric shock depends upon both the size of the current and the time for which the current flows through the body.

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Within how long must the RCB cut off the current if the person using the lawnmower is to be in no danger of serious injury?

...........................................................................................................................

...........................................................................................................................

Time = ................................... milliseconds (2)

(Total 6 marks)

Q47. (a) The diagram shows a 13 amp plug.

(i) What is wrong with the way this plug has been wired?

...........................................................................................................................

........................................................................................................................... (1)

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(ii) Why do plugs have a fuse?

...........................................................................................................................

........................................................................................................................... (1)

(b) The diagram shows an immersion heater which can be used to boil water in a mug.

(i) Which part of the immersion heater should be connected to the earth pin of the plug?

........................................................................................................................... (1)

(Total 3 marks)

Q48. (a) Draw lines to join the picture to the correct circuit symbol. The lamp has been done for you.

(2)

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(b) A family tent is to be fitted with a simple lighting circuit.

The diagram shows the first circuit used.

(i) Are the lamps connected in series or in parallel?

........................................................................................................................... (1)

(ii) This is not a good circuit for using in the tent. Why?

...........................................................................................................................

........................................................................................................................... (1)

The diagram shows the second circuit used.

(iii) Give two reasons why this circuit is better than the first circuit.

1. ......................................................................................................................

..........................................................................................................................

2. ......................................................................................................................

.......................................................................................................................... (2) (Total 6 marks)

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Q49. The information plate on a hairdrier is shown.

(a) What is the power rating of the hairdrier?

.................................................................................................................................. (1)

(b) (i) Write down the equation which links current, power and voltage.

........................................................................................................................ (1)

(ii) Calculate the current in amperes, when the hairdrier is being used. Show clearly how you work out your answer.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

Current = .............................. amperes (2)

(iii) Which one of the following fuses, 3A, 5A or 13A, should you use with this hairdrier?

........................................................................................................................ (1)

(c) The hairdrier transfers electrical energy to heat energy and kinetic energy.

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Use the following equation to calculate the efficiency of the hairdrier in transferring electrical energy into heat energy.

efficiency =

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

Efficiency = .............................. (2)

(d) One kilowatt-hour of electricity costs 6p. Use the following equation to calculate how much it will cost to use the hairdrier for 10 minutes.

cost of electricity = energy transferred × price per unit

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

Cost = ............................. (2)

(Total 9 marks)

Q50. The diagram shows the inside of a mains plug.

(a) Complete the table.

Wire Colour of insulation

Earth

Live

Neutral

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(3)

(b) The diagram shows a washing machine without an earth connection. The live wire has become loose and is touching the metal case of the washing machine.

(i) Draw on the diagram the path taken by the electricity when the person touches the metal case of the machine.

(1)

(ii) Describe how the path of the electricity would change if the washing machine had an earth connection.

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(c) Some electrical appliances use a cable which does not have an earth wire. Which one of the following appliances can safely use this type of cable?

hairdrier iron refrigerator

..................................................................................................................................

Give a reason for your answer.

..................................................................................................................................

.................................................................................................................................. (2)

(Total 8 marks)

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Q51. The circuit shown has four identical ammeters.

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

(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)

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(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.

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

What is component X?

.....................................................................................................................................

Give a reason for your answer.

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 10 marks)

Q52. The diagram shows a 12 volt lighting system. Each lamp has a power of 32 watts.

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

........................................................................................................................... (1)

(ii) Calculate the input current to the lighting system. Show clearly how you work out your answer.

....................................................................................................................................

....................................................................................................................................

current = ........................................................................ A (2)

(Total 3 marks)

Q53. 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.

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

(2)

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(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 (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)

Q54. The roads were very icy. An accident was recorded by a security camera.

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Car A was waiting at a road junction. Car B, travelling at 10 m/s, went into the back of car A. This reduced car B’s speed to 4 m/s and caused car A to move forward.

The total mass of car A was 1200 kg and the total mass of car B was 1500 kg.

(i) Write down the equation, in words, which you need to use to calculate momentum.

..................................................................................................................................... (1)

(ii) Calculate the change in momentum of car B in this accident.

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

.....................................................................................................................................

.....................................................................................................................................

Change in momentum = ......................................... (3)

(iii) Use your knowledge of the conservation of momentum to calculate the speed, in m/s, of car A when it was moved forward in this accident.

Show clearly how you work out your final answer.

.....................................................................................................................................

.....................................................................................................................................

Speed = ............................................................ m/s (3)

(Total 7 marks)

Q55. A set of Christmas tree lights is made from twenty identical lamps connected in series.

(a) Each lamp is designed to take a current of 0.25 A. The set plugs directly into the 230 V mains electricity supply.

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

..........................................................................................................................

.......................................................................................................................... (1)

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

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

Resistance = ...................................................................... (4)

(iii) What is the total resistance of the set of lights?

..........................................................................................................................

..........................................................................................................................

Total resistance = ........................................................ (1)

(b) How does the resistance of a filament lamp change as the temperature of the filament changes?

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (1)

(Total 7 marks)

Q56. The drawing shows three identical cells and two identical lamps joined in a circuit.

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(a) Use the correct symbols to draw a circuit diagram for this circuit.

(3)

(b) Each of the cells provides a potential difference (voltage) of 1.5 volts. What is the total potential difference (voltage) provided by all three cells?

............................................................................................................................ volts (1)

(c) Complete this sentence by crossing out the two lines in the box that are wrong.

The current through lamp 2 will be the current through lamp 1. (1)

(Total 5 marks)

Q57. The diagram shows two oscilloscope traces, A and B.

Trace A shows how the potential difference between the live and neutral terminals of an electricity supply changes with time.

(a) Describe how the potential of the live terminal varies with respect to the neutral terminal of the electricity supply.

....................................................................................................................................

.................................................................................................................................... (2)

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(b) What does trace B show?

....................................................................................................................................

.................................................................................................................................... (1)

(c) Each horizontal division on the oscilloscope represents 0.005 s.

(i) What is the period of this electricity supply?

..........................................................................................................................

Period = .................................. seconds (1)

(ii) Calculate the frequency of the supply.

..........................................................................................................................

Frequency = .................................. hertz (1)

(Total 5 marks)

Q58. (a) The circuit diagram drawn below includes a component labelled X.

(i) Use the equation in the box to calculate the potential difference across the 8 ohm resistor.

potential difference = current × resistance

Show clearly how you work out your answer.

..........................................................................................................................

..........................................................................................................................

Potential difference = ................................................. volts (2)

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

.......................................................................................................................... (1)

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

(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)

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Q59. (a) The diagram shows the inside of a correctly wired three-pin plug.

(i) What colour is the insulation on the wire labelled X?

Draw a ring around your answer.

blue brown green/yellow (1)

(ii) What name is given to the wire labelled Y?

Draw a ring around your answer.

earth live neutral (1)

(iii) What material would be suitable for the case of the plug?

.......................................................................................................................... (1)

(iv) Which one of the following is the correct circuit symbol for a fuse?

Draw a ring around your answer.

(1)

(b) A householder does not have enough electric sockets in the kitchen. To overcome the problem, the householder uses two adaptors to plug five appliances into a single electric socket.

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Explain why this is dangerous.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(Total 6 marks)

Q60. (a) A student rubs a nylon comb on the sleeve of his jumper.

(i) Use words from the box to complete the following sentence.

electrons hand jumper protons

The comb becomes negatively charged because ............................................ move

from the student’s ........................................... to the comb. (2)

(ii) What type of charge is left on the jumper?

....................................................................... (1)

(iii) The negatively charged comb is placed close to a charged plastic ruler. The comb and the ruler attract each other.

Complete the following sentence by drawing a ring around the correct line in the box.

The ruler is

negatively charged

positively charged

uncharged

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(1)

(b) Electrostatic charge can damage computer chips. People working with computer chips may wear a special bracelet, with a wire joining the bracelet to earth (the earth wire). Any negative charge on the person will flow through the wire to earth.

(i) Which one of the following materials should the bracelet be made from?

Draw a ring around your answer.

copper plastic rubber

Give a reason for your answer.

..........................................................................................................................

.......................................................................................................................... (2)

(ii) Which one of the following words is used to describe the rate of flow of charge through a wire?

Draw a ring around your answer.

current resistance voltage (1)

(Total 7 marks)

Q61. The picture shows an advert for an electric mobility scooter.

(a) The batteries are joined in series.

(i) What is the potential difference provided by the batteries to the motor?

...........................................................................................................................

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(1)

(ii) The batteries supply a direct current (d.c.).

What is a direct current (d.c.)?

...........................................................................................................................

........................................................................................................................... (1)

(b) At 2.5 m/s on flat ground, the motor takes a current of 3.0 A from the batteries.

(i) Explain why a bigger current is taken from the batteries when the scooter is going uphill at 2.5 m/s.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(ii) What effect does travelling uphill have on the range of the scooter?

........................................................................................................................... (1)

(c) The mass of the scooter driver is 80 kg.

Use the equation in the box to calculate the kinetic energy of the scooter and driver when they are travelling at maximum speed.

Q62. During car journeys, the driver will often become electrostatically charged. This is more noticeable on dry days than on damp, humid days.

(a) Explain what happens to cause the driver to become charged.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(b) Scientists were asked to find out whether the build-up of charge on the driver depends on the type of material used to make the driver’s clothes. The results of the investigation are given in the table.

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Material Humidity Temperature in °°°°C Charge on the driver

in millicoulombs

Nylon 48% 18 3.0 to 3.2

Wool 48% 18 2.4 to 2.5

Cotton 48% 18 1.4 to 1.7

Humidity is a measure of how much water vapour the air can hold.

(i) Why was it important that the scientists controlled the humidity?

...........................................................................................................................

........................................................................................................................... (1)

(ii) Does the data in the table show that the charge on the driver would always be less if they were to wear cotton clothing?

Give a reason for your answer.

...........................................................................................................................

........................................................................................................................... (1)

(Total 4 marks)

Q63. (a) The diagram shows the circuit used to investigate the resistance of a material. The diagram is incomplete; 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 thicknesses.

Graph 1 shows how the resistance changes with length.

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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.

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) and the equation in the box to calculate the potential difference across a 30 cm length of conducting putty.

potential difference = current × resistance

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.

Graph 2

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(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)

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

...........................................................................................................................

........................................................................................................................... (1)

(Total 10 marks)

Q64. (a) Look at this electrical safety information poster.

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(i) Complete the table to show which size fuse, 3 A or 13 A, should be fitted to each of the appliances.

Appliance Power rating Fuse

Hairdryer 1600 W

Electric saw 350 W

Food mixer 1200 W

(2)

(ii) The plug of an electric kettle has been wrongly fitted with a 3 A fuse.

What will happen to the fuse when the kettle is switched on?

...........................................................................................................................

........................................................................................................................... (1)

(b) The drawing shows a toaster, which takes a current of 4 A from the 230 V mains electricity supply.

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(i) Use the equation in the box to calculate the power of the toaster.

Power (watt, W)

= current

(ampere, A) ×

potential difference (volt, V)

Show clearly how you work out your answer.

...........................................................................................................................

...........................................................................................................................

Power = ............................................... W (2)

(ii) A householder rewires the toaster with a new cable and plug. The diagram shows how the new cable has been connected to the plug.

Explain why the toaster may not be safe to use.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(c) The diagram shows the oscilloscope traces produced by four different electricity supplies. The settings on the oscilloscope are the same for each electricity supply.

(i) Which two supplies give a direct current (d.c.)?

................... and ................... (1)

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(ii) Supply K provides a peak potential difference of 6 V.

What is the peak potential difference provided by supply M?

........................................................................................................................... (1)

(Total 9 marks)

Q65. The diagram shows someone accidentally touching the live wire inside a dismantled 230 volt mains electricity socket.

A current flows through the person giving him an electric shock.

(a) (i) Use the equation in the box to calculate the current that will flow through the person.

potential difference = current × resistance

Show clearly how you work out your answer.

...........................................................................................................................

...........................................................................................................................

Current = ............................................................ A (2)

(ii) Rubber is a good insulator.

Explain why it is a good idea for electricians to wear rubber soled boots when working.

...........................................................................................................................

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...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(b) If the current flowing through a person is too high, the person cannot let go of the electrical source.

Different people were tested to see whether the ability to let go of an electrical source depended on the frequency of the current.

The results of the test are shown in the graph.

(i) What is the frequency of the mains electricity supply in the UK?

............................................................ (1)

(ii) From a safety point of view, is the frequency of the UK mains electricity supply suitable?

Give a reason for your answer.

...........................................................................................................................

........................................................................................................................... (1)

(c) The diagram shows how the electric supply cable is connected to an electric kettle. The earth wire is connected to the metal case of the kettle.

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If a fault makes the metal case live, the earth wire and the fuse inside the plug protect anyone using the kettle from an electric shock.

Explain how.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 8 marks)

Q66. A circuit was set up as shown in the diagram.

(a) Each cell provides a potential difference of 1.5 volts.

(i) What is the total potential difference provided by the four cells in the circuit?

...........................................................................................................................

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Total potential difference = .............................. volts (1)

(ii) What will be the reading on the voltmeter?

........................................................................................................................... (1)

(b) The current through the lamp is 0.20 amps. The current through the resistor is 0.10 amps.

What is the reading on the ammeter?

.....................................................................................................................................

Reading on ammeter = .............................. amps (1)

(c) Use a phrase from the box to complete the following sentence.

greater than equal to smaller than

The resistance of the lamp is ............................................................ 60 Ω.

Give a reason for your answer.

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 5 marks)

Q67. (a) The graphs, A, B and C, show how the current through a component varies with the potential difference (p.d.) across the component.

Draw a line to link each graph to the correct component. Draw only three lines.

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(2)

(b) Each of the circuits, J, K and L, include two diodes.

In which one of the circuits, J, K or L, would the filament lamp be on?

............................................................ (1)

(Total 3 marks)

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Q68. (a) Describe the difference between an alternating current (a.c.) and a direct current (d.c.).

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(b) The diagram shows the information plate on the bottom of an electric wallpaper steamer.

(i) Use the equation in the box to calculate the current used by the steamer.

power = current × potential difference

Show clearly how you work out your answer.

...........................................................................................................................

...........................................................................................................................

Current .............................. A (2)

(ii) Which one of the following fuses should be used inside the plug of the steamer?

Draw a ring around your answer.

1 A 3 A 5 A 10 A 13 A (1)

(Total 5 marks)

Q69. The diagram shows a simple type of car rear window heater. The six heating elements are exactly the same.

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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.

Show clearly how you work out your answer.

.....................................................................................................................................

.....................................................................................................................................

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)

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Q70. (a) The diagram shows the circuit used by a student to measure the power of a filament lamp.

Name a component connected in parallel with the filament lamp.

..................................................................................................................................... (1)

(b) By adding another component to the circuit, the student is able to obtain a range of ammeter and voltmeter readings.

Ammeter reading in

amps

Voltmeter reading in

volts

0.10 1.0

0.15 2.0

0.20 4.0

0.25 7.0

0.30 11.0

(i) Which one of the following components did the student add to the circuit?

Draw a ring around your answer.

fuse switch variable resistor (1)

(ii) What is the range of ammeter readings taken by the student?

from .............................. amps to .............................. amps (1)

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(iii) Use the data in the table and the equation in the box to calculate the maximum power of the filament lamp.

Show clearly how you work out your answer.

...........................................................................................................................

...........................................................................................................................

Power = .............................. W (3)

(c) Complete the following sentence by drawing a ring around the correct line in the box.

increases

As the temperature of a filament lamp increases, its resistance remains constant

decreases

(1)

(Total 7 marks)

##

(a) Use numbers given in the box to complete the following sentences.

12 50 110 230

In the UK, the mains electricity supply is ............................................................... volts.

The frequency of the UK mains electricity supply is .............................................. hertz. (2)

(b) The diagram shows a hairdryer designed to be used with the UK mains supply.

The cable connecting the hairdryer to the plug does not have an earth wire.

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Plastic cover

(i) Why does the hairdryer not need a cable with an earth wire?

...........................................................................................................................

........................................................................................................................... (1)

(ii) Which one of the following materials are the two wires inside the cable made from?

Draw a ring around your answer.

aluminium copper steel (1)

(Total 4 marks)

Q72. In the U.K. mains electricity is a 230 volt a.c. supply.

(a) Explain the difference between an a.c. (alternating current) electricity supply and a d.c. (direct current) electricity supply.

.........................................................................................................................................

.........................................................................................................................................

.........................................................................................................................................

.........................................................................................................................................

(2)

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(b) A householder has a 10.8 kW electric shower installed in the bathroom.

(i) Calculate the current drawn from the mains electricity supply by the shower.

Write down the equation you use, and then show clearly how you work out your answer.

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

Current = ..................................... A (3)

(ii) The table gives the maximum current that can safely pass through electric cables of different cross-sectional area.

Cross-sectional area

in mm 2

Maximum safe current in amps

1.0 11.5

2.5 20.0

4.0 27.0

6.0 34.0

10.0 46.0

16.0 62.0

The existing power sockets in the house are wired to the mains electricity supply using 2.5 mm2 cable.

Explain why the shower must not be connected to the mains electricity supply using 2.5 mm 2 cable.

...............................................................................................................................

...............................................................................................................................

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...............................................................................................................................

...............................................................................................................................

(2)

(iii) The circuit connecting the shower to the mains electricity supply must include a residual current circuit breaker (RCCB) and not a fuse.

Give two advantages of using a RCCB to protect a circuit rather than a fuse.

1 ............................................................................................................................

...............................................................................................................................

2 ............................................................................................................................

...............................................................................................................................

(2)

(Total 9 marks)

Q73. A student designed the circuit below to measure temperature using a thermistor.

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To calibrate the thermistor to measure temperature, the student placed the thermistor in a beaker of water at 0 °C and took the voltmeter reading. The student then heated the water slowly with a Bunsen burner. The student recorded the reading on the voltmeter every 10 °C.

(a) (i) Before calibrating the thermistor the student completed a risk assessment. Write down one possible hazard that the student should have written in the risk assessment and what the student should do to reduce the risk of the hazard causing an injury.

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

(2)

(ii) At 0 °C the reading on the ammeter is 0.5 A.

Calculate the reading on the voltmeter at 0 °C.

Write down the equation you use, and then show clearly how you work out your answer.

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

Voltmeter reading = ..................................... V (3)

(b) Most of the readings taken by the student are displayed in the graph.

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(i) How does the resistance of a thermistor change when the temperature of the thermistor increases?

...............................................................................................................................

...............................................................................................................................

(1)

(ii) Why does the reading on the voltmeter change when the temperature of the water increases?

...............................................................................................................................

...............................................................................................................................

(1)

(iii) What is the temperature interval that can be measured with this circuit?

...............................................................................................................................

(1)

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(iv) Once calibrated, between which temperatures would this circuit give the greatest resolution for temperature readings?

Tick ( ) one box.

20 °C to 40 °C

40 °C to 60 °C

60 °C to 80 °C

Give a reason for your answer.

...............................................................................................................................

...............................................................................................................................

(2)

(c) Thermistors have many practical uses, including being used as a thermometer to measure temperature.

Give one other practical use for a thermistor.

.........................................................................................................................................

.........................................................................................................................................

(1)

(Total 11 marks)

Q74. A student used the apparatus below to find out how the resistance of a thermistor changes with temperature.

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The student heated the water slowly using a Bunsen burner. The resistance of the thermistor was measured using an ohmmeter.

(a) (i) Before doing the experiment the student completed a risk assessment.

Which one of the following is a hazard in this experiment?

Tick ( ) one box.

Using an ohmmeter near water

Boiling water in a beaker

Hanging the thermistor in water

(1)

(ii) The student measured the water temperature using a temperature probe and data logger rather than a glass thermometer.

Give two reasons for using a temperature probe and data logger rather than a glass thermometer to measure temperature.

...............................................................................................................................

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...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

(2)

(b) The data obtained by the student is displayed in the graph.

(i) Why has the data been displayed as a line graph and not as a bar chart?

Tick ( ) one box.

Because resistance and temperature are both continuous variables

Because resistance and temperature are both control variables

Because resistance and temperature are both independent variables

(1)

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(ii) What conclusions should the student make from the data displayed in the graph?

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

(2)

(c) In which one of the following circuits is there likely to be a thermistor?

Tick ( ) one box.

One that automatically switches lights on when it gets dark

One that automatically monitors the moisture level in soil

One that acts as a thermostat to switch heating on and off

(1)

(Total 7 marks)

Q75. (a) Look at the electrical safety information poster.

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(i) Complete the table to show which size fuse, 3 A or 13 A, should be fitted to each of the appliances.

Appliance Power Fuse

Kettle 2200 W

Hair straighteners 75 W

Coffee maker 1260 W

(2)

(ii) The plug of a washing machine has been wrongly fitted with a 3 A fuse.

What will happen to the fuse when the washing machine is switched on?

...............................................................................................................................

...............................................................................................................................

(1)

(b) The diagram shows a hairdryer. The cable connecting the hairdryer to the plug does not have an earth wire.

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(i) Why does the hairdryer not need a cable with an earth wire?

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

(1)

(ii) The hairdryer takes a current of 5 A from the 230 V mains electricity supply.

Calculate the power of the hairdryer.

Write down the equation you use, and then show clearly how you work out your answer.

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

Power = ................................. W (3)

(Total 7 marks)

Q76. (a) The diagram shows a three-pin plug and electrical cable.

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(i) Name a suitable material to make:

1 the plug casing; ...........................................................................................

2 the inner cores of the cable. ........................................................................ (2)

(ii) The outside of the cable is made from plastic.

Why?

...............................................................................................................................

...............................................................................................................................

...............................................................................................................................

(1)

(b) The pictures show mains electricity being used to operate various devices.

Some of the pictures show the electricity being used in a dangerous way.

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In the box underneath each picture put:

a tick ( ) if the electricity is being used safely

a cross ( ) if the electricity is being used dangerously. (2)

(Total 5 marks)

Q77. Use words from the box to label the components, A, B, and C, in the circuit diagram.

cell diode lamp resistor switch

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(Total 3 marks)