# A wind turbine uses the generator effect to produce electricity. As the wind turns the turbine blades, a coil of wire rotates between two permanent magnets. Explain how a potential difference is induced in the coil and why the current produced is alternating.

> OCR A-Level Physics A (H556) — 4.3 Electrical circuits · Explain · 5 marks

> Wind turbines generate electricity for thousands of homes. Inside each turbine, a coil of wire is made to rotate continuously between two permanent magnets by the spinning blades.

## Mark scheme (5 marks)

1. The rotating coil cuts through the magnetic field (lines) / there is relative motion between the coil and the magnetic field
2. This change in magnetic field induces a potential difference across the ends of the coil
3. Because the coil is part of a complete circuit, a current flows
4. As the coil rotates, each side of the coil alternately moves upward then downward through the field / the direction of the force on the charges in the wire reverses every half turn
5. This means the current continuously changes direction, producing alternating current

## Key terms

- [generator effect](https://www.gradenine.co.uk/glossary/generator-effect)
- [potential difference](https://www.gradenine.co.uk/glossary/potential-difference)
- [coil](https://www.gradenine.co.uk/glossary/coil)

## Related

- [Revision notes for OCR A-Level Physics A (H556)](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-de2923a2) · Published by Druglandscape Ltd.