AQA Additional Science

Electricity GCSE questions

Q1. 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?

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(1)

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

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(1)

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

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(2)

Q2. 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?

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

(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)

Q3. 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.

(i) Explain why they attracted each other.

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

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(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.

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(ii) Explain your answer.

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(2)

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

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(3)

(Total 8 marks)

Q4. 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.

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(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.

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)

Q5. (a) Complete the sentence below to name the instrument used to measure electrical current.

The instrument used to measure electrical current is called ......................................

(1)

(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)

Q6. (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.

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(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)

(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.

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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)

Q7. 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.

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(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?

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(ii) with the nicad cell?

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(4)

(Total 9 marks)

Q8. 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.)?

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........................................................................................................................... (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.

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(2)

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

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(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.

Q9. The diagram shows an electrical circuit.

(a) Complete the two labels on the diagram.

(b) P and Q are meters.

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

What is meter Q measuring? .......................................................................................

(2)

(Total 4 marks)

Q10. The information plate on a hairdrier is shown.

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

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(1)

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

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(1)

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

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Current = .............................. amperes

(2)

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

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(1)

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

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

efficiency =

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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

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Cost = .............................

(2)

(Total 9 marks)

Q11. 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.

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

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

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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?

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Answer .............................. s

(2)

(Total 7 marks)

Q12. (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?

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Current = .................................. A

(1)

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

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(1)

(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.

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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.

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(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.

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(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.

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(2)

(Total 10 marks)

Q13. 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?

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

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(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?

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(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?

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

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(2)

(Total 12 marks)

Q14. 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. ................................................................................................................................

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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?

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................................................................................................................................... (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.

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

(Total 7 marks)

Q15. 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. Mains voltage is 240 V.

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

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(3)

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

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(2)

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

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(2)

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

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(2)

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

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(3)

(Total 12 marks)

Q16. (a) The diagram shows a three-pin plug and electrical cable.

Name a suitable material to make:

the plug casing .................................................................

the inner cores of the cable. ..............................................

Give the reason for your choice of each material.

plug casing .....................................................................................................

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

inner core of the cable ...................................................................................

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

(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.

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 6 marks)

Q17. (a) Look at the electrical safety information poster.

(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.

Explain why the washing machine stops working shortly after it is switched on.

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(2)

(b) Complete these two sentences.

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

The frequency of the UK mains electricity supply is ............................. hertz.

(2)

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

K L M N

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

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(1)

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

What is the peak potential difference provided by supply M?

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(1)

(iii) Which supply provides the largest potential difference?

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(1)

(d) The diagram shows a hairdryer. The cable connecting the hairdryer to the plug does not have an earth wire.

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

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............................................................................................................. (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.

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Power = ............................................................. W

(2)

(Total 12 marks)

Q19. 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.

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

(b) What does trace B show?

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

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

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

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

(ii) Calculate the frequency of the supply.

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

(Total 5 marks)

Q22. (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. ................................................................................................................................

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

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

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(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

(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?

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

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(6)

(Total 9 marks)

Q23. In the UK 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.

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(2)

(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, then show clearly how you work out your answer and give the unit.

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Current = ....................................................

(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 mm

2 cable.

Use the data in the table to 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 ............................................................................................................

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(2)

(Total 9 marks)