# Explain what happens to the charge stored and the energy stored in a capacitor when the potential difference across it is doubled.

> AQA A-Level Physics (7408) — 3.7.4 Capacitance · Explain · 5 marks

> A capacitor is connected to a power supply. The potential difference across the capacitor is increased.

## Mark scheme (5 marks)

1. Charge stored doubles (when potential difference is doubled)
2. Because charge is directly proportional to potential difference / Q = CV and C is constant
3. Energy stored increases by a factor of four / energy quadruples
4. Because energy stored is proportional to V² / E = ½CV² so doubling V multiplies energy by 2² = 4
5. The capacitance itself does not change / capacitance is a fixed property of the capacitor

## Key terms

- [potential difference](https://www.gradenine.co.uk/glossary/potential-difference)
- [charge stored](https://www.gradenine.co.uk/glossary/charge-stored)
- [energy stored](https://www.gradenine.co.uk/glossary/energy-stored)

## Related

- [Revision notes for AQA A-Level Physics (7408)](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-what-happens-to-the-charge-ba5fbd2d) · Published by Druglandscape Ltd.