# A step-up transformer is used at a power station to increase the voltage before electricity is transmitted through the National Grid. Explain why transmitting electricity at high voltage reduces energy losses in the transmission cables.

> Eduqas GCSE Physics — 8.3 Induced potential and transformers · Explain · 4 marks

> Power stations generate electricity at around 25 000 V. Step-up transformers increase this to 400 000 V before the electricity enters the transmission cables of the National Grid.

## Mark scheme (4 marks)

1. Increasing voltage causes a decrease in current (for the same power transmitted)
2. Heating effect / power loss in cables depends on the current
3. Lower current means less power/energy is lost as heat in the cables
4. This makes the transmission more efficient (less energy wasted / greater proportion of energy reaches consumers)

## Key terms

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

## Related

- [Revision notes for Eduqas GCSE Physics](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/a-step-up-transformer-is-used-at-1e71a857) · Published by Druglandscape Ltd.