Pearson Edexcel International GCSE (9–1) · PHYSICS · Section
TRANSFORMERS AND NATIONAL GRIDS
16 practice questions
Practice questions
1–10 of 16
Question 1
1 mark · Easy
Answer and see the solution →State the main purpose of a step-up transformer in the National Grid.
Question 2
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 3
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 4
1 mark · Easy
Answer and see the solution →Name the type of transformer used to increase voltage for transmission in the National Grid.
Question 5
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 6
1 mark · Easy
Answer and see the solution →Explain why power lines of the National Grid are placed high above the ground.
Question 7
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:
Question 8
1 mark · Easy
Answer and check →Which part of the National Grid comes immediately after electricity is generated at a power station?
- A.Step-down transformer
- B.Transmission cables
- C.Step-up transformer
- D.Domestic fuse box
Question 9
4 marks · Normal
Answer and see the solution →The diagram below shows part of a National Grid system used to distribute electricity from a power station to homes.
A simplified National Grid: Power Station, Step-up Transformer, Transmission lines, Step-down Transformer, Homes. (a)[2 marks]Explain why step-up transformers are used after the power station before transmission.
(b)[2 marks]Explain why step-down transformers are used near homes before the electricity enters houses.
Question 10
4 marks · Normal
Answer and see the solution →A step-up transformer in the National Grid has 120 turns on its primary coil and 6,000 turns on its secondary coil. The primary coil is connected to an alternating voltage of 8 V.
(a)[3 marks]Calculate the voltage across the secondary coil.
(b)[1 mark]Explain whether this transformer increases or decreases the current in the secondary coil compared to the primary coil, assuming 100% efficiency.