# A thermistor is connected in series with a fixed resistor and a battery. Explain what happens to the current through the circuit as the temperature of the thermistor increases.

> Edexcel A-Level Physics (9PH0) — 10.1 Stars, life cycles and cosmology · Explain · 5 marks

> A thermistor and a fixed resistor of 200 Ω are connected in series with a 12 V battery. The thermistor is placed in water that is gradually heated from 10 °C to 60 °C.

## Mark scheme (5 marks)

1. As temperature increases, the resistance of the thermistor decreases
2. The total resistance of the series circuit decreases
3. Using V = IR / linking potential difference, current and resistance — since V is constant, a lower resistance means a larger current
4. The current through the circuit increases
5. The potential difference across the fixed resistor increases (as the current through it increases)

## Key terms

- [thermistor](https://www.gradenine.co.uk/glossary/thermistor)
- [current](https://www.gradenine.co.uk/glossary/current)
- [series](https://www.gradenine.co.uk/glossary/series)

## Related

- [Revision notes for Edexcel A-Level Physics (9PH0)](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-thermistor-is-connected-in-series-d841819f) · Published by Druglandscape Ltd.