# Explain how a transformer is used in the National Grid to reduce energy loss when electricity is transmitted over long distances.

> WJEC GCSE Physics (Wales) — 1.9 Electromagnetism · Explain · 4 marks

> Electricity generated at a power station is transmitted across the country through power cables at very high voltages before being supplied to homes and businesses.

## Mark scheme (4 marks)

1. A step-up transformer increases the voltage (potential difference) before transmission
2. Increasing voltage causes the current to decrease (for the same power)
3. Lower current means less energy is lost (as heat) in the power cables
4. A step-down transformer reduces the voltage to a safe level for use in homes/businesses

## Key terms

- [transformer](https://www.gradenine.co.uk/glossary/transformer)

## 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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-a-transformer-is-used-ce9cfa40) · Published by Druglandscape Ltd.