# A loudspeaker contains a coil of wire placed inside a magnetic field. When a current flows through the coil, the coil experiences a force and moves. Explain how reversing the direction of the current affects the force on the coil, and state two factors that would increase the size of this force.

> AQA GCSE Physics (8463) — 4.7.2 The motor effect · Explain · 4 marks

> A loudspeaker works by passing a varying electrical current through a coil of wire situated inside a magnetic field. The interaction between the two magnetic fields causes the coil to move, pushing a cone back and forth to produce sound.

## Mark scheme (4 marks)

1. Reversing the current reverses the direction of the force on the coil
2. This is because the direction of the force depends on the direction of the current (Fleming's Left-Hand Rule)
3. Increasing the size of the current increases the force
4. Increasing the strength of the magnetic field increases the force

## Key terms

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

## Related

- [Revision notes for AQA GCSE Physics (8463)](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-loudspeaker-contains-a-coil-of-364369de) · Published by Druglandscape Ltd.