# A student connects a battery to two lamps. The student first connects the lamps in series, then reconnects them in parallel. Explain how the brightness of each lamp changes when the circuit is changed from series to parallel, and why this happens.

> WJEC A-Level Physics (Wales) — 2.2 DC circuits · Explain · 5 marks

> A battery has a fixed voltage. When two identical lamps are connected in series, each lamp glows dimly. The circuit is then changed so the two identical lamps are connected in parallel across the same battery.

## Mark scheme (5 marks)

1. In a series circuit the voltage is shared between the two lamps (each lamp gets less than the full battery voltage)
2. In a parallel circuit each lamp receives the full battery voltage
3. A greater voltage across each lamp (in parallel) means a greater current through each lamp
4. Each lamp is brighter in parallel than in series because more power is transferred / more energy per second
5. In a series circuit the current is the same through both lamps but is smaller (than in parallel) because total resistance is higher

## Related

- [Revision notes for WJEC A-Level Physics (Wales)](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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