Pearson Edexcel International GCSE (9–1) · PHYSICS · Chapter
Electromagnetism
68 practice questions
Topics covered
Practice questions
21–30 of 33 · Easy
Question 21
2 marks · Easy
Answer and see the solution →State and explain why transformers only work with alternating current (a.c.) and not with direct current (d.c.).
Question 22
3 marks · Easy
Answer and see the solution →A transformer has 120 turns on its primary coil and 480 turns on its secondary coil. The input voltage is 6 V a.c.
(a)[1 mark]Is this transformer a step-up or a step-down transformer? Explain your answer.
(b)[2 marks]Calculate the output voltage from the secondary coil.
Question 23
3 marks · Easy
Answer and see the solution →Look at the diagram of a transformer below and answer the questions.
Diagram of a transformer (a)[2 marks]Name the part labelled 'core' in the diagram and state its purpose in the transformer.
(b)[1 mark]Is this transformer a step-up or a step-down transformer? Explain your answer.
Question 24
1 mark · Easy
Answer and see the solution →State the main purpose of a step-up transformer in the National Grid.
Question 25
2 marks · Easy
Answer and see the solution →Electricity leaves a power station at 25,000 V. A step-up transformer increases the voltage for transmission.
(a)[1 mark]Explain why increasing the voltage is important before transmitting electricity.
(b)[1 mark]What effect does increasing the voltage have on the current in the transmission cables?
Question 26
1 mark · Easy
Answer and check →What is the typical voltage in household sockets after passing through a step-down transformer in the UK?
- A.400,000 V
- B.25,000 V
- C.230 V
- D.9 V
Question 27
1 mark · Easy
Answer and see the solution →Name the type of transformer used to increase voltage for transmission in the National Grid.
Question 28
2 marks · Easy
Answer and see the solution →Describe what happens to the voltage and the current when electrical energy passes through a step-down transformer near a town.
(a)[1 mark]State what happens to the voltage.
(b)[1 mark]State what happens to the current.
Question 29
1 mark · Easy
Answer and see the solution →Explain why power lines of the National Grid are placed high above the ground.
Question 30
2 marks · Easy
Answer and see the solution →The transmission lines carry electricity at a low current. Give two reasons why this is an advantage in the National Grid.
(a)[1 mark]Reason 1:
(b)[1 mark]Reason 2: