# A step-up transformer is used at a power station before electricity enters the National Grid. Describe how a step-up transformer works, from the alternating current entering the primary coil to the higher potential difference produced across the secondary coil.

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

## Mark scheme (4 marks)

1. The alternating current in the primary coil produces a changing magnetic field (in the iron core).
2. The changing magnetic field passes through / cuts through the secondary coil.
3. A potential difference is induced across the secondary coil.
4. The secondary coil has more turns than the primary coil, so the induced potential difference is greater (stepped up).

## Key terms

- [step-up transformer](https://www.gradenine.co.uk/glossary/step-up-transformer)
- [primary coil](https://www.gradenine.co.uk/glossary/primary-coil)
- [secondary coil](https://www.gradenine.co.uk/glossary/secondary-coil)
- [potential difference](https://www.gradenine.co.uk/glossary/potential-difference)
- [alternating current](https://www.gradenine.co.uk/glossary/alternating-current)

## Related

- [Revision notes for AQA GCSE Physics (8463)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" 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-step-up-transformer-is-used-at-c07cb507) · Published by Druglandscape Ltd.