# Explain why an ohmic conductor has a constant resistance, and describe how the current through it changes when the potential difference across it is doubled.

> AQA GCSE Physics (8463) — 4.2.1 Current, potential difference and resistance · Explain · 4 marks

> A student investigates a length of resistance wire kept at a constant temperature. She measures the current through the wire for several different values of potential difference.

## Mark scheme (4 marks)

1. An ohmic conductor has a constant resistance because its temperature does not change (is kept constant)
2. Current is directly proportional to potential difference (for an ohmic conductor at constant temperature)
3. When potential difference is doubled, the current also doubles
4. This follows from V = IR; since R is constant, doubling V must double I

## Key terms

- [ohmic conductor](https://www.gradenine.co.uk/glossary/ohmic-conductor)
- [potential difference](https://www.gradenine.co.uk/glossary/potential-difference)
- [resistance](https://www.gradenine.co.uk/glossary/resistance)
- [current](https://www.gradenine.co.uk/glossary/current)

## Related

- [Revision notes for AQA GCSE Physics (8463)](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-an-ohmic-conductor-has-bcd51a85) · Published by Druglandscape Ltd.