# A wind turbine uses electromagnetic induction to generate electricity. The turbine blades turn a coil of wire inside a magnetic field. Explain why a greater wind speed produces a larger induced EMF in the coil.

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

> Wind turbines generate electricity for homes and businesses. Inside the turbine, a coil of wire rotates within a magnetic field. On a calm day the blades rotate slowly; on a windy day the blades rotate much faster.

## Mark scheme (5 marks)

1. A greater wind speed causes the coil to rotate faster / increases the rate of rotation of the coil
2. The magnetic field lines are cut more frequently / the coil cuts through magnetic field lines more quickly
3. This increases the rate of change of flux / the magnetic flux changes more rapidly
4. A larger induced EMF is produced because the induced EMF depends on / is proportional to the rate of change of flux
5. A larger induced EMF drives a larger current through the circuit / produces a greater electrical output

## Key terms

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

## 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-wind-turbine-uses-electromagnetic-induction-1271b773) · Published by Druglandscape Ltd.