Power

What is Power?

Within Physics, which covers forces, energy, waves, electricity, magnetism, light and space explained through motion and experiments, this topic explains Power. Physics topics explain how things move, push, heat up and carry energy, so each one here pairs a definition with a live model you can change.

Check that you can explain Power in your own words and give one example from everyday life. If you can do that, you have understood the core idea.

Understanding Power explains how the physical world behaves, from sport and transport to electricity and medicine.

Power in detail

Power is the rate of transferring energy or doing work: P = E/t = W/t, measured in watts (W), where 1 W = 1 J/s. A 60 W lamp transfers 60 joules each second. For moving objects, P = Fv.

A more powerful machine does the same work in less time, or more work in the same time. Electrical power is P = VI, and energy used is shown on bills in kilowatt-hours (kWh). Comparing power ratings helps choose appliances and understand why climbing stairs quickly feels harder than walking up slowly.

How the interactive helps you understand Power

Watch the circuit in the interactive. Use any sliders or buttons it offers to change the values and see how the circuit responds.

Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of Power.

Real-life uses and examples

• Explain everyday devices, such as brakes, lifts or chargers, using Power.
• Use Power to make sense of a practical and its results.
• Answer “explain” questions by linking Power to a clear cause and effect.

Common mistakes to avoid

• Forgetting that some quantities, such as force or velocity, also have a direction.
• Mixing up Power with a related quantity that has different units.
• Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.