Who this is for: Cambridge IGCSE Coordinated Science (0654) students who want electrical energy — E = VIt, power and kilowatt-hours — to become a reliable source of marks instead of a formula they apply with wrong units.
What query it owns: how to understand and revise electrical energy in Cambridge IGCSE Coordinated Science.
Why this is safe: this page owns the electrical energy revision-guide angle, while Tutopiya’s Electrical Energy subtopic page owns the learning resource and the free Electrical Energy quiz owns the practice.

Electrical energy is the energy transferred when charge moves through a potential difference. Cambridge IGCSE Coordinated Science (0654) expects you to use E = VIt, P = VI, P = I²R and convert between joules and kilowatt-hours (kWh) for bill calculations. This guide links each equation to the calculation questions examiners set.

Key takeaways

• Electrical energy: E = VIt (or E = VQ), unit joule (J).
• Electrical power: P = VI = I²R = V²/R, unit watt (W).
• 1 kWh = 3.6 × 10⁶ J — the unit on electricity bills.
• Cost = energy (kWh) × price per kWh.
• Higher power means faster energy transfer (not more total energy unless time is fixed).

What is electrical energy in Cambridge IGCSE Coordinated Science?

When current flows through a component, energy is transferred from the supply to the component (and often to the surroundings as heat). Power measures the rate of energy transfer. Household electricity meters measure energy in kilowatt-hours, which is convenient for billing because power (kW) × time (h) gives energy directly.

You can read the full explanation, diagrams and notes on Tutopiya’s Electrical Energy subtopic page before you attempt questions.

Key energy and power equations

Equation	When to use
E = VIt	Energy transferred by a device
P = VI	Power from voltage and current
P = I²R	Power when current and resistance known
P = V²/R	Power when voltage and resistance known
Energy (kWh) = Power (kW) × Time (h)	Electricity bill calculations

Example: 2 kW heater for 3 h → energy = 2 × 3 = 6 kWh.

Electrical energy in past-paper wording: command words that matter

Command word / phrase	What the question wants	Typical electrical energy stem
Calculate	Use E = VIt or P = VI	”Calculate the energy transferred in 5 minutes.”
Define	Precise meaning	”Define electrical power.”
Determine	Find with working	”Determine the cost of running the appliance.”
Show that	Prove a given value	”Show that the energy used is 7.2 × 10⁶ J.”

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

1. “A 12 V lamp carries a current of 0.5 A for 2 minutes. Calculate the energy transferred.” t = 120 s → E = VIt = 12 × 0.5 × 120 = 720 J. Mark-scheme reward: time in seconds + correct substitution.
2. “A 3 kW kettle is used for 4 minutes. Calculate the energy in kWh.” t = 4/60 h = 0.0667 h → E = 3 × 0.0667 = 0.20 kWh (or 0.2 kWh). Reward: time converted to hours.
3. “Define the kilowatt-hour (kWh).” The energy transferred by a 1 kW device operating for 1 hour (= 3.6 × 10⁶ J). Reward: power × time definition.

Test yourself with the Electrical Energy quiz once you can use E = VIt, P = VI and kWh calculations.

How electrical energy connects to the rest of Coordinated Science physics

Electrical energy builds on Electrical Quantities and Series And Parallel Circuits, and links to Energy (energy stores and transfers). The Cambridge IGCSE Coordinated Science resource hub links every Electric Circuits subtopic.

Common mistakes students make

• Forgetting to convert minutes to seconds in E = VIt (or to hours for kWh).
• Confusing power (W) with energy (J or kWh).
• Using P = VI when only I and R are given (use P = I²R instead).
• Thinking a higher-power device always uses more total energy (depends on time too).
• Mixing up kW (power) and kWh (energy).

When you need more support

If electrical energy questions keep costing marks, work through the Electrical Energy quiz, then get focused help from a Cambridge IGCSE Coordinated Science tutor.

Frequently asked questions

Is electrical energy hard in Coordinated Science? Learn E = VIt, P = VI and the kWh formula with correct unit conversions — that covers most questions.

What is the difference between power and energy? Power (W) is the rate of energy transfer; energy (J or kWh) is the total amount transferred.

What is a kilowatt-hour? The energy transferred by a 1 kW device running for 1 hour, equal to 3.6 × 10⁶ J.

How do I revise electrical energy effectively? Practise E = VIt and kWh calculations with unit conversions, then take the Electrical Energy quiz.

Ready to master Cambridge IGCSE Coordinated Science electrical energy?

Start with the Electrical Energy subtopic page, then book a free trial with a Cambridge IGCSE Coordinated Science specialist to turn energy calculations into guaranteed marks.

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