# Explain why the lamps in a parallel circuit remain at the same brightness when one lamp is removed from the circuit, but the lamps in a series circuit all go out when one lamp is removed.

> OCR GCSE Physics A: Gateway Science (J249) — P3.2 Simple circuits · Explain · 4 marks

> A student is comparing how lamps behave in series and parallel circuits. She notices that switching off one lamp in a parallel circuit does not affect the other lamps, but removing one lamp from a series circuit causes all the other lamps to go out.

## Mark scheme (4 marks)

1. In a parallel circuit, each lamp is connected across its own separate branch / the full potential difference of the supply
2. Removing one lamp in a parallel circuit breaks only that branch, so current can still flow through the remaining lamps
3. In a series circuit, all components share a single path / loop for current
4. Removing one lamp in a series circuit breaks the single path, so no current can flow anywhere in the circuit and all lamps go out

## Key terms

- [series circuit](https://www.gradenine.co.uk/glossary/series-circuit)
- [parallel circuit](https://www.gradenine.co.uk/glossary/parallel-circuit)

## Related

- [Revision notes for OCR GCSE Physics A: Gateway Science (J249)](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-lamps-in-a-b14e9751) · Published by Druglandscape Ltd.