# A rectangular coil of wire is connected to a sensitive galvanometer and is rotated steadily inside a uniform magnetic field produced by two permanent magnets. After several complete rotations, the coil is brought to rest with its plane parallel to the magnetic field. Describe how the induced voltage changes as the coil is rotated, and explain three separate ways in which the maximum induced voltage could be increased.

> Pearson Edexcel International GCSE Physics (4PH1) — 6.3 Electromagnetic induction · Describe · 4 marks

> A rectangular coil of wire is connected to a sensitive galvanometer and rotated steadily inside a uniform magnetic field. The coil completes several full rotations before being brought to rest.

## Mark scheme (4 marks)

1. As the coil rotates, the induced voltage continuously changes / alternates (accept: the galvanometer needle deflects back and forth); the voltage is greatest when the plane of the coil is parallel to the magnetic field and zero when the plane is perpendicular to the field.
2. Use a stronger magnet / increase the strength of the magnetic field.
3. Increase the speed of rotation of the coil (so the magnetic field through the coil changes more quickly).
4. Increase the length of wire inside the magnetic field — for example by increasing the number of turns on the coil, using a larger coil area, or using a longer wire.

## Key terms

- [induced voltage](https://www.gradenine.co.uk/glossary/induced-voltage)
- [magnetic field](https://www.gradenine.co.uk/glossary/magnetic-field)

## Related

- [Revision notes for Pearson Edexcel International GCSE Physics (4PH1)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" 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-rectangular-coil-of-wire-is-3be2673a) · Published by Druglandscape Ltd.