# A student wraps a length of wire into a coil and connects it to a battery. She then places a steel nail inside the coil. Explain how the steel nail becomes magnetic, and describe three ways the student could increase the strength of the magnetic field produced by the coil.

> OCR A-Level Physics A (H556) — 4.3 Electrical circuits · Explain · 5 marks

> A student is investigating how to make and strengthen an electromagnet using a coil of wire, a battery, and a steel nail.

## Mark scheme (5 marks)

1. Current flowing through the coil produces a magnetic field (around the wire / inside the coil)
2. The steel nail is placed inside the magnetic field of the coil and becomes an induced magnet (domains align / nail becomes temporarily magnetised)
3. Increase the number of turns (coils) of wire
4. Increase the size of the current (through the coil)
5. Use an iron core instead of a steel nail / replace the nail with an iron core

## Key terms

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

## Related

- [Revision notes for OCR A-Level Physics A (H556)](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-wraps-a-length-of-3d4d3494) · Published by Druglandscape Ltd.