# A student is investigating two electric heaters, Heater A and Heater B, connected to the same mains supply. Heater A has a greater resistance than Heater B. The student says: 'The heater with the greater resistance will always transfer energy at a faster rate.' Explain whether the student is correct, referring to how resistance affects current and power in this circuit.

> OCR A-Level Physics B: Advancing Physics (H557) — 3.3 Work, energy and power · Explain · 5 marks

> Two electric heaters, Heater A and Heater B, are each connected separately to the same mains potential difference. Heater A has a greater resistance than Heater B.

## Mark scheme (5 marks)

1. The student is incorrect
2. Power (rate of energy transfer) depends on both current and voltage / P = IV
3. A greater resistance causes a smaller current to flow (at the same potential difference)
4. Heater A (greater resistance) therefore has a lower power / transfers energy at a slower rate than Heater B
5. Heater B (lower resistance) draws a larger current and therefore has a greater power / transfers energy at a faster rate

## Key terms

- [power](https://www.gradenine.co.uk/glossary/power)
- [resistance](https://www.gradenine.co.uk/glossary/resistance)
- [current](https://www.gradenine.co.uk/glossary/current)

## Related

- [Revision notes for OCR A-Level Physics B: Advancing Physics (H557)](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-is-investigating-two-electric-c3cd90f7) · Published by Druglandscape Ltd.