# An engineer designs an electromagnet to lift heavy steel objects in a scrapyard. She winds a coil of wire around an iron core and connects it to a power supply. Explain how the electromagnet works and describe three ways the engineer could increase the strength of the electromagnet.

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

> An electromagnet is used in a scrapyard to lift and move heavy steel objects. The electromagnet is made from a solenoid with an iron core connected to a direct current power supply.

## Mark scheme (5 marks)

1. Current flowing through the coil/wire produces a magnetic field
2. The iron core increases the strength of the magnetic field (because magnetic field lines pass more easily through iron than air)
3. Any one valid method to increase strength: increase the current
4. Any second valid method to increase strength: increase the number of turns/coils of wire
5. Any third valid method to increase strength: use a different/better core material OR increase the cross-sectional area of the coil OR increase the length of the coil

## Key terms

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

## 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/an-engineer-designs-an-electromagnet-to-a623a648) · Published by Druglandscape Ltd.