# Explain why a transformer only works with alternating current (AC) in the primary coil and not with direct current (DC).

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

## Mark scheme (4 marks)

1. AC in the primary coil produces a continuously changing magnetic field
2. This changing magnetic field passes through (cuts through) the secondary coil
3. This induces a potential difference (and current) in the secondary coil
4. DC produces a constant (steady) magnetic field, so no change occurs and no potential difference is induced in the secondary coil

## Key terms

- [alternating current](https://www.gradenine.co.uk/glossary/alternating-current)
- [primary coil](https://www.gradenine.co.uk/glossary/primary-coil)
- [transformer](https://www.gradenine.co.uk/glossary/transformer)

## 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-why-a-transformer-only-works-511492a8) · Published by Druglandscape Ltd.