Pearson Edexcel International GCSE (9–1) · PHYSICS · Section
ELECTRICAL POWER
16 practice questions
Practice questions
1–8 of 8 · Normal
Question 1
4 marks · Normal
Answer and see the solution →A hairdryer uses the heating effect of an electric current. The label on the hairdryer states 'Power: 1200 W'.
(a)[2 marks]Explain how the heating effect of current is used in a hairdryer.
(b)[2 marks]Calculate the energy transferred by the hairdryer in 5 minutes of use.
Question 2
3 marks · Normal
Answer and see the solution →Two halogen bulbs are labelled 50 W and 70 W. Both are in use for 20 seconds. The bulbs convert electrical energy into heat and light.
Energy transferred in 20 seconds Bulb Power (W) Time (s) Energy (J) A 50 20 B 70 20 (a)[1 mark]Calculate the energy transferred by bulb A in 20 seconds.
(b)[1 mark]Calculate the energy transferred by bulb B in 20 seconds.
(c)[1 mark]Explain why bulb B is brighter than bulb A.
Question 3
3 marks · Normal
Answer and see the solution →Look at these two electrical appliances:
Appliance Wire material Wire resistance Toaster Nichrome (metal alloy) High Mains cable in wall Copper Low (a)[3 marks]Explain why the heating element in a toaster uses a wire with high resistance, but the wires in a mains cable use low resistance copper.
Question 4
1 mark · Normal
Answer and see the solution →Which of the following best describes the unit watt (W)?
- A.The energy transferred per coulomb of charge.
- B.The charge that passes a point every second.
- C.The energy transferred per second.
- D.The resistance to current flow in a circuit.
Question 5
3 marks · Normal
Answer and see the solution →A mains-powered oven uses a heating element with a high resistance. The oven has a power rating of 2000 W and is switched on for 15 minutes.
(a)[1 mark]State why the heating element must have a high resistance.
(b)[2 marks]Calculate the total energy transferred to the oven in this time.
Question 6
3 marks · Normal
Answer and see the solution →A student connects a thin filament lamp and a mains kettle in parallel to a 230 V supply. Both use the heating effect of current.
(a)[2 marks]Explain why the lamp glows but the kettle does not.
(b)[1 mark]State one use of the heating effect of electric current, other than in a lamp or a kettle.
Question 7
4 marks · Normal
Answer and see the solution →A washing machine has a power rating of 1800 W. It is used for 40 minutes during a wash cycle.
(a)[2 marks]Calculate the total energy transferred by the washing machine in one wash cycle.
(b)[2 marks]Suggest one effect on the wash cycle if the heating element had a much lower resistance than normal.
Question 8
3 marks · Normal
Answer and see the solution →Some electrical appliances have double insulation and do not need an earth wire.
(a)[1 mark]Describe what is meant by double insulation.
(b)[2 marks]Explain why double insulated appliances do not need an earth wire.