Lesson 4.2.4.3

4.2.4.3 The National Grid Quiz: AQA Physics, Unit 2

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.2.4.3, The National Grid: 20 multiple choice questions for the AQA GCSE Physics (8463), Unit 2: Electricity, written with Revision Ninja.

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The 20 questions

  1. What best describes the National Grid system?

    • Power stations only
    • Cables and transformers
    • Underground water pipes
    • Domestic batteries

  2. What is the main function of a step-up transformer in the National Grid?

    • Decrease frequency
    • Increase potential difference
    • Increase current
    • Decrease potential difference

  3. What is the main function of a step-down transformer in the National Grid?

    • Generates electricity
    • Decreases voltage
    • Increases current
    • Increases voltage

  4. Why is high potential difference used for power transmission across the National Grid?

    • Increases cable speed
    • Reduces thermal loss
    • Simplifies transformer design
    • Prevents short circuits

  5. A power station outputs 1 MW at 100 kV. What current flows in the transmission cables?

    • 10 A
    • 0.1 A
    • 100 A
    • 1000 A

  6. The same 1 MW is transmitted at 10 kV instead. What current flows?

    • 100 A
    • 0.1 A
    • 1000 A
    • 10 A

  7. If transmission potential difference increases from 10 kV to 100 kV for the same power, how does cable power loss change?

    • Increases 100 times
    • Decreases 10 times
    • Decreases 100 times
    • Increases 10 times

  8. Why is the National Grid considered an efficient way to transfer electrical energy?

    • High cable resistance
    • Low transmission voltage
    • Low transmission current
    • Zero energy wasted

  9. Which two components are mainly used to form the National Grid?

    • Lamps and motors
    • Batteries and generators
    • Resistors and switches
    • Cables and transformers

  10. Why is electricity not transmitted over long distances at domestic voltage?

    • Causes high current loss
    • Damages power stations
    • Requires direct current
    • Stops magnetic fields

  11. At which points are transformers used in the National Grid system?

    • Substations only
    • Power stations only
    • Homes only
    • Both ends

  12. Which statement correctly describes the role of the National Grid?

    • Consumes electrical energy
    • Stores electrical energy
    • Transfers electrical power
    • Generates electrical energy

  13. In the power loss equation for transmission cables (I squared R), which variable must be minimised?

    • Length
    • Resistance
    • Current
    • Voltage

  14. If current in a cable is halved with resistance unchanged, how does power lost change?

    • Falls by 2
    • Rises by 4
    • Falls by 4
    • Rises by 2

  15. Which change allows power to be transmitted through the National Grid with less current?

    • Increasing resistance
    • Increasing potential difference
    • Decreasing frequency
    • Decreasing potential difference

  16. Which transformer is used at the start of the grid to reduce the current for transmission?

    • A step-down transformer
    • A step-up transformer
    • A resistor network
    • A battery converter

  17. A transmission cable of resistance 0.5 ohms carries 200 A. What power is lost as heat in the cable?

    • 200 W
    • 100 W
    • 20000 W
    • 40000 W

  18. Which of these is a consumer on the National Grid?

    • A coal-fired power station
    • A household
    • A step-up transformer
    • A transmission cable

  19. A grid transmits 2 MW at 20 kV. What current flows in the cables?

    • 1000 A
    • 10 A
    • 100 A
    • 0.1 A

  20. What is the main problem with transmitting mains electricity over long distances at 230 V?

    • Frequent fuse blowing
    • Slow signal speed
    • High heating losses
    • Excessive magnetic fields

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