Pearson Edexcel International GCSE (9–1) · PHYSICS · Section
ALTERNATING CURRENT AND DIRECT CURRENT
16 practice questions
Practice questions
1–8 of 8 · Normal
Question 1
4 marks · Normal
Answer and see the solution →A table lamp is rated at 60 W and is connected to a 240 V mains supply.
(a)[2 marks]Calculate the current in the lamp when it is operating at full power.
(b)[2 marks]Calculate the energy transferred if the lamp is left on for 30 minutes.
Question 2
1 mark · Normal
Answer and check →Which of the following best describes alternating current (a.c.) as opposed to direct current (d.c.)?
- A.A current that is always in the same direction and constant size.
- B.A current that regularly reverses direction and changes size with time.
- C.A current supplied only by batteries and cells.
- D.A current supplied only by power stations.
Question 3
3 marks · Normal
Answer and see the solution →A 24 V power supply powers a motor drawing a current of 1.5 A. The motor operates for 5 minutes. Calculate the total energy transferred to the motor.
Question 4
2 marks · Normal
Answer and see the solution →Describe two differences between the current from a cell and the current from the mains electricity supply.
Question 5
4 marks · Normal
Answer and see the solution →An electric heater has a power rating of 1.2 kW and operates from a 240 V supply.
(a)[2 marks]Calculate the current taken by the heater.
(b)[2 marks]Calculate the energy transferred by the heater in 10 minutes.
Question 6
4 marks · Normal
Answer and see the solution →A 12 V battery is connected to a lamp. The current in the lamp is measured as 0.4 A.
(a)[2 marks]Calculate the power supplied to the lamp.
(b)[2 marks]Calculate the energy transferred by the lamp in 2 minutes.
Question 7
1 mark · Normal
Answer and see the solution →State the unit and one symbol used for each of the following: (i) current, (ii) energy transferred.
Question 8
3 marks · Normal
Answer and see the solution →The graph below shows how the voltage changes with time for an alternating current (AC) supply and a direct current (DC) supply.
Voltage versus time for AC and DC supply. (a)[1 mark]Describe the main difference between the two graphs.
(b)[1 mark]State which graph represents the supply from a cell.
(c)[1 mark]Give one reason why the mains supply uses AC rather than DC.