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

> WJEC GCSE Physics (Wales) — 1.2 Generating electricity · Explain · 4 marks

## Mark scheme (4 marks)

1. High voltage reduces the current in the power cables
2. Lower current means less energy is lost / dissipated (as heat) in the power cables
3. This makes the transmission of electricity more efficient
4. The power cables are metal wires / conductors that have resistance, so a smaller current reduces the heating effect

## Key terms

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

## Related

- [Revision notes for WJEC GCSE Physics (Wales)](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-da233455) · Published by Druglandscape Ltd.