Explain how the generator effect is used in a thermal power station to produce an electrical current.

Edexcel GCSE Physics (1PH0) — 13.1 Electromagnetic induction (Phys only) · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

In a thermal power station, burning fossil fuels releases energy that is eventually used to generate electricity on a large scale.

Model answer (4 marks)

The burning of fossil fuels heats water to produce high‑pressure steam. The steam drives a turbine, causing a coil of wire to rotate inside a magnetic field. The relative motion between the conductor and the field induces a potential difference across the coil, which drives an electric current – the generator effect.

Examiner tips

  • Use the word ‘induce’ to show understanding of the generator effect.
  • Mention the turbine and magnetic field explicitly – they are key to the process.
  • Show the chain: heat → steam → turbine rotation → coil in field → induced EMF → current.
  • Keep the answer concise – 4 marks only.

Common mistakes

  • Failing to mention the turbine or magnetic field.
  • Confusing the generator effect with the motor effect.
  • Using vague terms like ‘electricity is produced’ without explaining the induction process.

Mark scheme (4 marks)

  1. The thermal energy from burning fuel heats water to produce steam (which is put under pressure to drive a turbine)
  2. The turbine rotation causes a coil of wire to spin inside a magnetic field
  3. There is relative motion between the coil (conductor) and the magnetic field
  4. This induces a potential difference (and therefore a current flows in the coil / circuit) — this is the generator effect

Key terms in this question

generator effect

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