# A wind turbine uses the generator effect to generate electricity. The turbine blades are connected to a coil of wire that rotates between two permanent magnets. Explain how the generator effect produces an alternating current in the coil, and state two changes to the turbine that would increase the size of the induced potential difference.

> OCR A-Level Physics B: Advancing Physics (H557) — 4.5 Quantum physics · Explain · 5 marks

> Wind turbines are used across the UK to generate electricity for the National Grid. Inside each turbine, the kinetic energy of the spinning blades is converted into electrical energy using the generator effect.

## Mark scheme (5 marks)

1. The rotating coil experiences a change in magnetic field (as it cuts through the magnetic field lines)
2. This induces a potential difference across the ends of the coil
3. Because the coil rotates continuously, the direction of the induced current reverses every half turn, producing alternating current
4. First correct change to increase the induced potential difference — e.g. increase the number of turns on the coil
5. Second correct and different change to increase the induced potential difference

## Key terms

- [generator effect](https://www.gradenine.co.uk/glossary/generator-effect)
- [alternating current](https://www.gradenine.co.uk/glossary/alternating-current)
- [potential difference](https://www.gradenine.co.uk/glossary/potential-difference)
- [permanent magnet](https://www.gradenine.co.uk/glossary/permanent-magnet)

## Related

- [Revision notes for OCR A-Level Physics B: Advancing Physics (H557)](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-wind-turbine-uses-the-generator-813653ab) · Published by Druglandscape Ltd.