# A student sets up an electromagnet by wrapping a wire into a coil and connecting it to a battery. The student wants to make the electromagnet as strong as possible. Explain how the design of the electromagnet affects its magnetic field strength, and describe TWO changes the student could make to increase the strength of the magnetic field produced.

> OCR A-Level Physics B: Advancing Physics (H557) — 4.5 Quantum physics · Explain · 5 marks

> An electromagnet consists of a solenoid with an iron core. The student is investigating how different factors affect the strength of the magnetic field it produces.

## Mark scheme (5 marks)

1. An iron core increases the strength of the magnetic field (compared to an air core)
2. Increasing the number of turns/coils increases the magnetic field strength
3. Increasing the current increases the magnetic field strength
4. The coiling of the wire causes the individual magnetic fields to align / combine into one larger field
5. Correctly identifies TWO valid changes the student could make (e.g. increase the current AND increase the number of turns), each clearly stated as a change

## Key terms

- [electromagnet](https://www.gradenine.co.uk/glossary/electromagnet)
- [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 "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-sets-up-an-electromagnet-0a205644) · Published by Druglandscape Ltd.