# A bicycle dynamo contains a permanent magnet that spins near a coil of wire. As the magnet spins faster, a larger voltage is produced across the coil. Explain how the dynamo produces a voltage and why spinning the magnet faster increases the voltage produced.

> Cambridge International IGCSE Physics (0625) — 4.5 Electromagnetic effects · Explain · 4 marks

## Mark scheme (4 marks)

1. The spinning magnet produces a changing magnetic field through the coil
2. The changing magnetic field induces a voltage (e.m.f.) in the coil
3. Spinning faster means the magnetic field changes more rapidly / the rate of change of magnetic field is greater
4. A greater rate of change of magnetic field induces a larger voltage

## Key terms

- [permanent magnet](https://www.gradenine.co.uk/glossary/permanent-magnet)

## Related

- [Revision notes for Cambridge International IGCSE Physics (0625)](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-bicycle-dynamo-contains-a-permanent-6e741e09) · Published by Druglandscape Ltd.