# Explain why step-up transformers are used in the National Grid before electrical power is transmitted along the transmission cables.

> AQA GCSE Physics (8463) — 4.2.5 The National Grid · Explain · 4 marks

> Electricity generated at a power station is passed through a step-up transformer before entering the National Grid's transmission cables.

## Mark scheme (4 marks)

1. The step-up transformer increases the potential difference
2. Because power is constant (P = IV), increasing potential difference causes the current to decrease
3. Lower current means less energy is lost (as heat) in the transmission cables
4. This makes the transmission of electrical power more efficient

## Key terms

- [step-up transformer](https://www.gradenine.co.uk/glossary/step-up-transformer)
- [National Grid](https://www.gradenine.co.uk/glossary/national-grid)
- [transmission cables](https://www.gradenine.co.uk/glossary/transmission-cables)

## 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-step-up-transformers-are-used-bc46d7e4) · Published by Druglandscape Ltd.