Who this is for: Cambridge IGCSE Coordinated Science (0654) students who want power — the rate at which energy is transferred — to become a reliable source of marks instead of a vague everyday word.
What query it owns: how to understand and revise power in Cambridge IGCSE Coordinated Science.
Why this is safe: this page owns the power revision-guide angle, while Tutopiya’s Power subtopic page owns the learning resource and the free Power quiz owns the practice.

Power is the rate at which energy is transferred or work is done. Cambridge IGCSE Coordinated Science (0654) expects you to use P = E/t (or P = W/t), state the unit watt (W), and distinguish power from total energy. A 60 W lamp transfers 60 joules of energy every second — that is what examiners test.

Key takeaways

• Power = energy transferred per unit time → P = E/t or P = W/t.
• Unit: watt (W); 1 W = 1 J/s.
• Kilowatt (kW): 1 kW = 1000 W.
• Higher power means energy is transferred faster, not necessarily more total energy.
• Power links directly to Energy and Work.

What is power in Cambridge IGCSE Coordinated Science?

Power measures how quickly energy is transferred from one store to another. A 100 W bulb and a 10 W bulb both transfer energy, but the 100 W bulb does so ten times faster. In exams, you calculate power using energy and time, or work and time. Understanding power as a rate — not a total amount — is the key to explanation and calculation questions.

Read the full notes and diagrams on Tutopiya’s Power subtopic page before attempting past-paper questions.

Power equations and units

Equation	When to use
P = E/t	Energy transferred (E in J, t in s)
P = W/t	Work done (W in J, t in s)
E = P × t	Find total energy from power and time

Unit	Equivalent
1 watt (W)	1 joule per second (J/s)
1 kilowatt (kW)	1000 W

Example: a heater transfers 3000 J in 10 s → P = 3000/10 = 300 W.

How to calculate power — step by step

1. Identify whether the question gives energy (E) or work done (W).
2. Write the equation: P = E/t or P = W/t.
3. Convert time to seconds if needed (minutes → × 60).
4. Substitute values and calculate; state the answer in watts (W).
5. Check with the free Power quiz.

Power in past-paper wording: command words that matter

Command word / phrase	What the question wants	Typical power stem
Define	State meaning + unit	”Define the term power.”
Calculate	Use P = E/t	”Calculate the power of the motor.”
Explain	Link power to rate	”Explain why the 100 W bulb is brighter than the 40 W bulb.”
Compare	Rate vs total energy	”Compare the power of two appliances that use the same total energy.”

Worked exam-style stems (how to answer the wording)

1. “A lamp transfers 1200 J of energy in 20 s. Calculate its power.” P = E/t = 1200/20 = 60 W. Mark-scheme reward: correct substitution, unit W.
2. “Define power and state its SI unit.” Power is the rate at which energy is transferred (or work is done); unit is the watt (W). Reward: rate + energy/work + watt.
3. “A 2 kW kettle runs for 3 minutes. Calculate the energy transferred.” P = 2000 W; t = 3 × 60 = 180 s → E = P × t = 2000 × 180 = 360 000 J (360 kJ). Reward: unit conversion + correct multiplication.

Test yourself with the Power quiz once you can define power, use P = E/t, and convert between W and kW.

How power connects to the rest of Coordinated Science physics

Power sits at the end of the Work, Energy And Power topic. It builds on Energy (energy stores and transfers) and Work (W = Fd). Energy Resources applies power to real-world generation. The Cambridge IGCSE Coordinated Science resource hub links every Work, Energy And Power subtopic.

Common mistakes students make

• Confusing power (rate) with energy (total amount transferred).
• Forgetting to convert minutes to seconds before dividing.
• Using kW in calculations without converting to W first.
• Stating the unit as J instead of W for power answers.
• Mixing up P = E/t with E = P × t when rearranging.

When you need more support

If power calculations keep costing marks, work through the Power quiz, then get focused help from a Cambridge IGCSE Coordinated Science tutor.

Frequently asked questions

What is the formula for power in Coordinated Science? P = E/t — power equals energy transferred divided by time, measured in watts (W).

What is the difference between power and energy? Energy is the total amount transferred (joules); power is how fast that transfer happens (joules per second).

How do I convert kilowatts to watts? Multiply by 1000: 1 kW = 1000 W.

How do I revise power effectively? Practise P = E/t calculations, time conversions, then take the Power quiz.

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