# A generator in a power station produces electricity by electromagnetic induction. Explain how rotating a coil of wire inside a magnetic field produces an induced potential difference, and state what must be true about the coil's motion for the induced potential difference to be at its maximum value.

> Eduqas GCSE Physics — 8.3 Induced potential and transformers · Explain · 4 marks

## Mark scheme (4 marks)

1. The rotating coil cuts through magnetic field lines (flux linkage changes)
2. This induces a potential difference (or EMF) in the coil
3. The induced potential difference alternates (reverses direction) as the coil rotates
4. The induced potential difference is at its maximum when the coil is moving parallel to the magnetic field (perpendicular to the field lines) / cutting field lines at the greatest rate

## Key terms

- [induced potential difference](https://www.gradenine.co.uk/glossary/induced-potential-difference)
- [electromagnetic induction](https://www.gradenine.co.uk/glossary/electromagnetic-induction)

## Related

- [Revision notes for Eduqas GCSE Physics](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-generator-in-a-power-station-35c0a266) · Published by Druglandscape Ltd.