# Describe how electricity generated at a power station reaches homes through the National Grid, including the role of transformers.

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

> A new offshore wind farm has been connected to the National Grid. The electricity it generates must travel hundreds of kilometres before reaching domestic customers.

## Mark scheme (4 marks)

1. A step-up transformer increases the potential difference (voltage) from the power station / wind farm to the power lines
2. Electricity is transmitted along power cables at very high voltage / potential difference
3. Transmitting at high voltage reduces the current, which reduces the energy lost as heat in the power cables
4. A step-down transformer decreases the potential difference to a safer / lower voltage suitable 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 "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-how-electricity-generated-at-a-2104a6e5) · Published by Druglandscape Ltd.