This topic summary covers Knowledge Organiser: 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 12 of 12 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Knowledge Organiser: Power
Key Equations
- P = E/t — power from energy and time
- P = W/t — power from work done and time
- P = IV — electrical power
- P = I²R — electrical power (current + resistance)
- P = V²/R — electrical power (voltage + resistance)
- Energy (kWh) = Power (kW) × Time (h)
Key Terms
- Power — rate of energy transfer
- Watt (W) — 1 J/s
- Kilowatt (kW) — 1,000 W
- Kilowatt-hour (kWh) — unit of energy (not power)
Unit Conversions
- 1 kW = 1,000 W
- 1 MW = 1,000,000 W
- 1 kWh = 3,600,000 J
- Minutes → seconds: × 60
- Hours → seconds: × 3,600
Common Pitfalls
- kWh is energy, not power
- Always convert time to seconds for P = E/t
- Higher power ≠ more total energy used
- Power is a scalar (no direction)
Practice questions for Power
Which of the following is the correct definition of power?
State what is meant by the term 'power' in physics and state its unit.
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).