# An engineer designs an electromagnet to be used in a scrapyard to lift heavy steel objects. Explain how the engineer could increase the strength of the magnetic field produced by the electromagnet, and explain why steel objects are attracted to it when it is switched on.

> OCR A-Level Physics B: Advancing Physics (H557) — 4.3 Electrical circuits · Explain · 5 marks

> An electromagnet consists of a solenoid with an iron core. It is connected to a power supply and used to sort magnetic materials at a recycling facility.

## Mark scheme (5 marks)

1. Increasing the current increases the strength of the magnetic field
2. Increasing the number of turns/coils on the solenoid increases the field strength
3. The iron core increases the strength of the magnetic field (because field lines pass through iron more easily than air)
4. When the electromagnet is switched on, the steel objects become induced magnets
5. Induced magnetism always produces an attractive force, so the steel is attracted to the electromagnet

## 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/an-engineer-designs-an-electromagnet-to-890e5009) · Published by Druglandscape Ltd.