- Power = Energy / Time (P = E/t) or Power = Work done / Time (P = W/t)
- Unit of power: watt (W), where 1 W = 1 J/s
- Electrical power: P = IV, P = I²R, P = V²/R
- Energy consumed: E = Pt (in joules) or Energy (kWh) = Power (kW) × Time (h)
- Higher power = energy transferred more quickly, not necessarily more total energy
- A 60 W bulb on for 10 hours uses the same energy as a 600 W appliance on for 1 hour
- Power is a scalar quantity (no direction)
This key facts covers Key Facts — Power within Power for GCSE Physics. Revise Power in Energy for GCSE Physics with 14 exam-style questions and 25 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 6 of 12 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Power
Which of the following is the correct definition of power?
A microwave oven transfers 54,000 J of energy. It has a power rating of 900 W. Calculate how long the microwave was switched on. Use the equation: power = energy transferred / time Give your answer in seconds (s).
Quick recall flashcards
What is mechanical power?
Mechanical power is the rate at which mechanical work is done or mechanical energy is transferred, calculated using P = W/t.
What is power?
Power is the rate at which energy is transferred or work is done. It is measured in watts (W).