# A student sets up a simple electric motor using a rectangular coil of wire in a magnetic field. The motor stops rotating when the plane of the coil is perpendicular to the magnetic field. Explain why the coil begins to rotate when a current flows, and why it would continue to rotate rather than stop in a real motor.

> Eduqas GCSE Physics — 8.2 Magnetic effects of currents and the motor effect · Explain · 4 marks

> A rectangular coil of wire is connected to a direct current (d.c.) supply and placed between the poles of a permanent magnet.

## Mark scheme (4 marks)

1. A current-carrying conductor in a magnetic field experiences a force (motor effect)
2. The forces on opposite sides of the coil act in opposite directions, producing a turning effect / torque / causing the coil to rotate
3. A split-ring commutator reverses the direction of the current every half turn
4. This keeps the turning force (torque) acting in the same direction so the coil continues to rotate

## Key terms

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

## Related

- [Revision notes for Eduqas GCSE Physics](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-student-sets-up-a-simple-739f46a1) · Published by Druglandscape Ltd.