# A student connects a 9 V battery to three identical lamps in series. Each lamp has a potential difference of 3 V across it and a current of 0.2 A flowing through it. Explain how energy is transferred in this circuit, starting from the battery and ending with what happens inside each lamp.

> Pearson Edexcel International GCSE Physics (4PH1) — 2.2 Energy and voltage in circuits · Explain · 4 marks

## Mark scheme (4 marks)

1. Chemical energy in the battery is transferred to electrical energy (in the circuit / to the charges)
2. The potential difference (voltage) across each lamp shows the energy transferred per unit charge between those two points / the battery does work on the charges
3. Electrical energy is transferred to thermal (heat) energy and light energy in each lamp / current does work against the resistance of the lamp
4. This heating occurs because electrons collide with ions in the metal filament / the filament's temperature increases due to these collisions

## Key terms

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

## Related

- [Revision notes for Pearson Edexcel International GCSE Physics (4PH1)](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/a-student-connects-a-9-v-c940af4b) · Published by Druglandscape Ltd.