# A student places a plotting compass at several positions around a bar magnet. Describe what the student would observe about the direction and spacing of the compass needle at different positions, and explain what these observations reveal about the magnetic field surrounding the magnet.

> OCR A-Level Physics A (H556) — 4.4 Waves · Describe and Explain · 5 marks

> A student is investigating the magnetic field around a bar magnet using small plotting compasses placed at various distances and positions around the magnet.

## Mark scheme (5 marks)

1. The compass needle points from north to south (along the field lines) / the needle points away from the north pole and towards the south pole of the magnet.
2. The direction of the compass needle changes at different positions around the magnet, showing the field lines curve around the magnet.
3. The compass needles are closer together (more concentrated) near the poles / nearer the magnet.
4. Greater concentration of field lines (closer compass needle positions) indicates a stronger magnetic field in that region.
5. As distance from the magnet increases, the spacing between compass needle directions increases / field lines become more spread out, showing the field strength decreases with distance.

## Key terms

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

## Related

- [Revision notes for OCR A-Level Physics A (H556)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and 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-places-a-plotting-compass-00919893) · Published by Druglandscape Ltd.