# A string of Christmas tree lights is wired in series. When one bulb breaks, all the other lights go out. Explain why all the lights go out when one bulb breaks in a series circuit.

> Eduqas GCSE Physics — 7.2 Series and parallel circuits · Explain · 4 marks

> A string of Christmas tree lights contains ten identical bulbs connected in series to a mains supply.

## Mark scheme (4 marks)

1. In a series circuit there is only one path for the current to flow
2. When the bulb breaks, the circuit becomes incomplete / the circuit is broken / there is a gap in the circuit
3. Current cannot flow through a broken/incomplete circuit
4. With no current flowing, the remaining bulbs receive no current and so do not light up

## Key terms

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

## Related

- [Revision notes for Eduqas GCSE Physics](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-string-of-christmas-tree-lights-4d66c7e2) · Published by Druglandscape Ltd.