# A straight wire carrying an electric current is placed at right angles to a uniform magnetic field. Explain how the direction of the force on the wire can be reversed, and describe what happens to the size of the force if the current in the wire is doubled.

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

## Mark scheme (4 marks)

1. Reversing the direction of the current reverses the direction of the force on the wire
2. Reversing the direction of the magnetic field also reverses the direction of the force on the wire
3. Doubling the current doubles the size of the force
4. The force on the wire is caused by the interaction between the magnetic field of the current and the external magnetic field (the motor effect)

## Key terms

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

## 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-straight-wire-carrying-an-electric-15177293) · Published by Druglandscape Ltd.