# A student strokes an unmagnetised cobalt rod several times in the same direction with one pole of a permanent magnet. After stroking, the cobalt rod is found to retain its magnetism for a long time. Explain why cobalt can be permanently magnetised and describe what would happen if the north pole of a bar magnet were brought close to one end of the magnetised cobalt rod.

> Pearson Edexcel International GCSE Physics (4PH1) — 6.1 Magnetism · Explain · 4 marks

## Mark scheme (4 marks)

1. Cobalt is a magnetically hard material
2. Magnetically hard materials retain / keep their magnetism once the magnetising field is removed
3. One end of the cobalt rod will be a magnetic pole that either attracts or repels the north pole of the bar magnet
4. Like poles repel and unlike poles attract — so whether there is attraction or repulsion depends on which pole of the cobalt rod faces the north pole of the bar magnet

## Key terms

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

## Related

- [Revision notes for Pearson Edexcel International GCSE Physics (4PH1)](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-strokes-an-unmagnetised-cobalt-981b66f2) · Published by Druglandscape Ltd.