# Explain why the resistance of a metallic conductor increases as its temperature increases, using a model of charge carriers and the lattice structure of the metal.

> IB DP Physics Higher Level (2023 syllabus) — B.5 Current and circuits · Explain · 4 marks

## Mark scheme (4 marks)

1. Free electrons act as the charge carriers responsible for current in a metallic conductor.
2. As temperature increases, the positive ions in the lattice vibrate with greater amplitude.
3. The more vigorously vibrating ions present a larger effective cross-sectional obstruction, increasing the frequency of collisions between free electrons and the lattice ions.
4. More frequent collisions reduce the mean drift velocity of the electrons for a given potential difference, so resistance (V/I) increases.

## Key terms

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

## Related

- [Revision notes for IB DP Physics Higher Level (2023 syllabus)](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-the-resistance-of-a-69e1a237) · Published by Druglandscape Ltd.