# Explain how a changing magnetic field in a transformer induces a potential difference in the secondary coil.

> AQA GCSE Physics (8463) — 4.7.3 Induced potential, transformers and the National Grid (Phys only) · Explain · 4 marks

> A transformer has a primary coil connected to an alternating current supply and a secondary coil wound around the opposite end of an iron core.

## Mark scheme (4 marks)

1. The alternating current in the primary coil creates a changing magnetic field
2. The iron core carries / concentrates this changing magnetic field to the secondary coil
3. The changing magnetic field cuts through / links with the secondary coil
4. A potential difference is induced across the secondary coil (by the generator effect)

## Key terms

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

## Related

- [Revision notes for AQA GCSE Physics (8463)](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/explain-how-a-changing-magnetic-field-fe627a45) · Published by Druglandscape Ltd.