# A plotting compass is placed near a long, straight wire carrying a current. Explain what happens to the plotting compass when the current in the wire is switched on, and what would happen to the compass reading if the current in the wire were then doubled.

> Edexcel GCSE Physics (1PH0) — 12.1 Magnetism and the motor effect · Explain · 4 marks

> A student investigates the effect of a current-carrying wire on a nearby plotting compass. The compass is placed a fixed distance from the wire. Initially there is no current flowing through the wire.

## Mark scheme (4 marks)

1. When the current is switched on, the wire produces a magnetic field around it
2. The plotting compass deflects / changes direction / aligns with the magnetic field produced by the wire
3. When the current is doubled, the magnetic field around the wire becomes stronger
4. The compass reading/deflection is greater / the compass needle deflects further from its original position (because the field is stronger)

## Key terms

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

## Related

- [Revision notes for Edexcel GCSE Physics (1PH0)](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-plotting-compass-is-placed-near-623cd6f8) · Published by Druglandscape Ltd.