# A student sets up an electromagnet by wrapping wire around an iron core and connecting it to a power supply. The student wants to make the electromagnet as strong as possible. Describe four factors the student could change to increase the strength of the magnetic field produced by the electromagnet, and for each factor state what change should be made.

> OCR A-Level Physics B: Advancing Physics (H557) — 4.2 Energy, power and resistance · Describe · 5 marks

> An electromagnet consists of a solenoid with an iron core. The strength of the magnetic field it produces depends on several factors.

## Mark scheme (5 marks)

1. Increase the size (magnitude) of the current flowing through the wire
2. Increase the number of turns (coils) of wire around the core
3. Use an iron core (rather than air or a non-magnetic material) / keep the iron core as it allows field lines to pass through more easily than air
4. Increase the cross-sectional area of the coil / use a wider coil
5. Increase the length of the coil (keeping other factors constant) to include more turns over a greater length

## Key terms

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

## Related

- [Revision notes for OCR A-Level Physics B: Advancing Physics (H557)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" 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-sets-up-an-electromagnet-8ba82bb8) · Published by Druglandscape Ltd.