# Explain why adding a second resistor in series to a circuit makes it harder for current to flow, and describe what happens to the potential difference across each resistor compared to the potential difference of the power supply.

> Edexcel GCSE Physics (1PH0) — 10.1 Electricity and circuits · Explain · 4 marks

> A student builds a circuit with a battery and a single resistor. She then adds a second resistor connected in series with the first.

## Mark scheme (4 marks)

1. Adding a second resistor increases the total resistance of the circuit
2. Greater total resistance means the current in the circuit decreases
3. The potential difference is shared between the two resistors (in series)
4. The sum of the potential differences across each resistor equals the potential difference of the power supply

## Key terms

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

## Related

- [Revision notes for Edexcel GCSE Physics (1PH0)](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-adding-a-second-resistor-2979f8ca) · Published by Druglandscape Ltd.