# A generator in a power station uses electromagnetic induction to produce electricity. Explain how changing the speed at which the generator spins affects the induced EMF produced, and describe TWO other changes a technician could make to the generator to increase the induced EMF.

> WJEC A-Level Physics (Wales) — 4.5 Electromagnetic induction · Explain · 5 marks

> A generator contains a coil of wire that rotates between the poles of a magnet. As the coil spins, an EMF is induced across its ends.

## Mark scheme (5 marks)

1. Increasing the speed of rotation increases the induced EMF (or decreasing speed decreases it)
2. Because the coil cuts through magnetic field lines more quickly / the rate of change of flux is greater
3. Increasing the strength of the magnet (using a stronger magnet) increases the induced EMF
4. Increasing the number of turns on the coil increases the induced EMF
5. Any second valid method correctly stated: e.g. wind the coil around an iron core / use a coil with a larger area

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Physics (Wales)](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-247f8929) · Published by Druglandscape Ltd.