# Explain why electricity is transmitted across the National Grid at very high voltages rather than at low voltages.

> OCR GCSE Physics A: Gateway Science (J249) — P6.2 Producing electricity · Explain · 4 marks

> The National Grid carries electricity from power stations to homes and businesses across the UK. Power cables stretch for hundreds of kilometres across the country.

## 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. This makes transmission of electricity more efficient
4. Step-up transformers are used at the power station to increase the voltage for transmission, and step-down transformers reduce the voltage to a safe level for domestic use

## Key terms

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

## 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)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-electricity-is-transmitted-across-803c0540) · Published by Druglandscape Ltd.