Pearson Edexcel International GCSE (9–1) · PHYSICS · Chapter
Mains Electricity
58 practice questions
Topics covered
Practice questions
21–30 of 30 · Normal
Question 21
2 marks · Normal
Answer and see the solution →State the main difference between alternating current (a.c.) and direct current (d.c.). Give one example of each.
Question 22
1 mark · Normal
Answer and check →Which device provides direct current (d.c.) only?
- A.Car battery
- B.Household mains supply
- C.Wind turbine generator
- D.Transformer
Question 23
3 marks · Normal
Answer and see the solution →A coffee machine is labelled 900 W, 230 V. Calculate:
(a)[3 marks]The current it draws from the mains when operating normally. Give your answer to 2 decimal places.
Question 24
4 marks · Normal
Answer and see the solution →A mobile phone charger is rated at 5 V and is connected to a current of 0.6 A.
(a)[1 mark]Calculate the power used by the charger.
(b)[3 marks]If the charger is used for 3 hours, calculate the total energy transferred in kilojoules (kJ).
Question 25
3 marks · Normal
Answer and see the solution →The voltage of two electricity supplies, X and Y, was measured over time. The results are given below:
Voltage measurements for supplies X and Y over time. Time (s) Supply X (V) Supply Y (V) 0 0 3 1 3 3 2 0 3 3 -3 3 4 0 3 On the axes below, plot the voltages of X and Y against time (from 0 to 4 s).
Question 26
3 marks · Normal
Answer and see the solution →A 150 W computer monitor runs on a 19 V supply. Calculate the current in the monitor and the total energy transferred if it is used for 2 hours.
(a)[2 marks]Calculate the current. Give your answer to 2 decimal places.
(b)[1 mark]Calculate the energy transferred in kilojoules (kJ).
Question 27
4 marks · Normal
Answer and see the solution →A student uses a 230 V electric fan with a power rating of 115 W. The fan's plug contains a fuse, and the outer casing is made of metal.
(a)[2 marks]Calculate the current drawn by the fan to two decimal places.
(b)[2 marks]State the most appropriate size of fuse that should be used in the fan's plug from these options: 3 A, 5 A, 13 A. Explain your answer.
Question 28
5 marks · Normal
Answer and see the solution →A metal-cased toaster and a plastic-cased kettle are shown below.
Appliance features Appliance Casing material Earth wire? Double insulation? Toaster Metal Yes No Kettle Plastic No Yes (a)[3 marks]Explain why the toaster requires an earth wire, but the kettle does not.
(b)[2 marks]State what would happen if the live wire in the toaster became loose and touched the metal case. Explain how the user is protected.
Question 29
4 marks · Normal
Answer and see the solution →A 800 W microwave oven is used in a home where the mains supply is 240 V.
(a)[2 marks]Calculate the current taken by the oven.
(b)[2 marks]The oven is used for 2 minutes. Calculate the total energy transferred by the oven during this time.
Question 30
3 marks · Normal
Answer and see the solution →An electric heater is rated at 2 kW and is connected to a 230 V mains supply. It is used for 30 minutes.
(a)[2 marks]Explain how the heater uses the heating effect of an electric current to warm up a room.
(b)[1 mark]Calculate the total energy transferred by the heater during this time.