# A student has two identical-looking metal rods. One rod is a permanent bar magnet and the other rod is made of unmagnetised iron. Without using any other equipment, the student can work out which rod is the magnet by using only the two rods. Explain how the student could do this, and explain the result they would observe to identify which rod is the magnet.

> WJEC A-Level Physics (Wales) — 4.4 Magnetic fields · Explain · 5 marks

## Mark scheme (5 marks)

1. The student should bring the end of one rod close to the middle (or along the length) of the other rod
2. A magnet attracts at its poles but has little or no magnetic force at its centre/middle
3. If both rods are brought end-to-end they will always attract (because iron is always attracted to a magnet, and two magnets can attract or repel)
4. If the magnet rod's end is placed against the centre of the unmagnetised iron rod, there will be attraction
5. If the unmagnetised iron rod's end is placed against the centre of the magnet rod, there will be little or no attraction, identifying the magnet rod as the one whose centre shows no pull

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Physics (Wales)](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-has-two-identical-looking-metal-17e0c711) · Published by Druglandscape Ltd.