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Physics Paper 1 · P2 · Lesson 2.13

Electrical power and energy

Power is how quickly energy is transferred.

Key ideas1 of 5

Power means energy each second

Power is the rate of energy transfer, measured in watts (W). A 100 W device transfers 100 J each second. A higher power transfers more energy in the same time.

Device A has a power rating of 20 watts; device B has a power rating of 100 watts.

1 W = 1 J/s. A power rating is not a total amount of energy.

Next: The National Grid →
Topic resources and sources

Daily 5 · Exam practice · Extra calculation practice · A4 revision sheet

Start with lessons 2.1–2.6 for the circuit basics. Lesson 2.15 offers extra calculation practice. The P2 specification content is shared by Foundation and Higher Tier; extra practice is not Higher Tier-only.

AQA Combined Science Trilogy specification · 6.2.4.1–6.2.4.2. Original notes, questions and diagrams. Circuit animations are simplified; motion is deliberately slowed. Measurements and example values are illustrative. All practical circuits use suitable supervised low-voltage apparatus.

Photographs: Photograph of the inside of a UK plug by Alby Reid, Public domain, released by the copyright holder; Electricity pylons near Grafham Water by Mat Fascione, CC BY-SA 2.0; Photoresistor 2 by oomlout, CC BY-SA 2.0. Images displayed without cropping or alteration.