# Explain why electricity generated at a power station is transmitted across the National Grid at very high voltages, rather than at the lower voltages used in homes.

> OCR GCSE Physics A: Gateway Science (J249) — P6.1 Energy resources · Explain · 4 marks

> Britain's National Grid distributes electricity from power stations to homes and businesses across the country. The electricity is transmitted along overhead power cables at very high voltages before being reduced to 230 V for domestic use.

## Mark scheme (4 marks)

1. High voltage transmission reduces the current in the power cables
2. A lower current results in less energy lost as heat in the power cables
3. Step-up transformers are used at the power station to increase the voltage for transmission
4. Step-down transformers are used to reduce the voltage to a safe level for domestic use

## Key terms

- [National Grid](https://www.gradenine.co.uk/glossary/national-grid)
- [voltage](https://www.gradenine.co.uk/glossary/voltage)

## Related

- [Revision notes for OCR GCSE Physics A: Gateway Science (J249)](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-electricity-generated-at-a-a12343a9) · Published by Druglandscape Ltd.