# An engineer uses an electric motor in a piece of industrial machinery. The motor contains a rectangular coil of wire placed between two permanent magnets. Explain how the motor produces continuous rotation.

> Edexcel A-Level Physics (9PH0) — 12.1 Newtonian gravity · Explain · 5 marks

> An electric motor converts electrical energy into kinetic energy. Inside the motor, a coil of wire is connected to a power supply and sits between the poles of two permanent magnets.

## Mark scheme (5 marks)

1. Current flows through the coil, producing a magnetic field around the wire
2. The coil's magnetic field interacts with the magnetic field of the permanent magnets
3. The two sides of the coil that are perpendicular to the magnetic field experience forces in opposite directions
4. The opposing forces on the two sides of the coil cause it to rotate
5. The direction of the current is reversed every half turn (e.g. using a split-ring commutator) so that the coil continues to rotate in the same direction

## Key terms

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

## Related

- [Revision notes for Edexcel A-Level Physics (9PH0)](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/an-engineer-uses-an-electric-motor-0cbcbfd9) · Published by Druglandscape Ltd.