Pearson Edexcel International GCSE (9–1) · PHYSICS · Unit
Electricity
249 practice questions
Topics covered
Practice questions
71–80 of 127 · Normal
Question 71
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 72
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 73
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.
Question 74
1 mark · Normal
Answer and check →Which statement correctly describes what happens to the current in a series circuit when the resistance is increased?
- A.The current increases.
- B.The current decreases.
- C.The current remains the same.
- D.The current becomes zero.
Question 75
4 marks · Normal
Answer and see the solution →A circuit contains a battery and two resistors, R1 and R2, connected in series. R1 = 4 Ω and R2 = 8 Ω. The battery supplies a voltage of 12 V.
(a)[1 mark]Calculate the total resistance in the circuit.
(b)[2 marks]Calculate the current in the circuit.
(c)[1 mark]Calculate the voltage across R2.
Question 76
2 marks · Normal
Answer and see the solution →State two advantages of using parallel circuits instead of series circuits for wiring lights in a house.
Question 77
3 marks · Normal
Answer and see the solution →A current of 0.8 A flows through a wire for 30 seconds. Calculate the total charge that passes through the wire. Include units in your answer.
Question 78
4 marks · Normal
Answer and see the solution →The table below shows the results of an experiment to investigate the current through a wire as the voltage is increased.
Measured values Voltage (V) Current (A) 0.5 0.10 1.0 0.20 1.5 0.30 2.0 0.40 2.5 0.50 a) Plot a graph of current (y-axis) against voltage (x-axis), and draw the best fit straight line.
b) Use your graph to state the relationship between current and voltage for a wire at constant temperature.
(a)[3 marks](b)[1 mark]Question 79
3 marks · Normal
Answer and see the solution →Explain, with reasons, why LDRs are often used in automatic lighting systems. State how their resistance changes with light intensity.
Question 80
4 marks · Normal
Answer and see the solution →Describe an experiment you could do to find the relationship between current and voltage for a resistor. Your answer should include:
- A description or diagram of the circuit you would use - How you would take your measurements - What you would record - How you would use the data to determine the relationship