# A sports centre has two electric water pumps, Pump A and Pump B, that move water around a heating system. Pump A has a potential difference of 230 V across it and a current of 4 A flowing through it. Pump B operates at the same potential difference but has twice the current of Pump A. Explain which pump transfers energy at a greater rate and why a higher current leads to a greater rate of energy transfer.

> OCR A-Level Physics A (H556) — 3.3 Work, energy and power · Explain · 5 marks

> Both pumps are connected to the same mains supply of 230 V and operate continuously. Pump B has a current of 8 A flowing through it.

## Mark scheme (5 marks)

1. Power is the rate at which energy is transferred (accept: power is energy transferred per second)
2. Power equals current multiplied by potential difference / P = IV
3. Pump B has a greater power / transfers energy at a greater rate because it has a higher current (at the same potential difference)
4. A higher current means more charge flows per second / greater rate of flow of charge
5. More charge flowing per second through the same potential difference means more energy transferred per second / greater power output

## Key terms

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

## Related

- [Revision notes for OCR A-Level Physics A (H556)](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-sports-centre-has-two-electric-e231d726) · Published by Druglandscape Ltd.