Learning objective

Define efficiency in terms of useful energy output and total energy input, using the equations: efficiency = (useful energy output / total energy input) × 100% and efficiency = (useful power output / total power input) × 100%.

Read the explanation, check the common trap, then practise with flashcards and questions.

Exam focus

Cambridge IGCSE Combined ScienceMotion, forces and energySupplement content

Study support

Understand this objective

Quick explanation

This point belongs to Energy, work and power, especially Energy, work and power outcomes.
You need to be able to define efficiency in terms of useful energy output and total energy input, using the equations: efficiency = (useful energy output / total energy input) × 100% and efficiency = (useful power output / total power input) × 100%.
The key ideas to know are Define and Calculate.
Use the linked flashcards and practice questions to check recall, then practise applying the idea in an exam-style answer.

Key concepts

DefineCalculate

Why it matters

This objective helps connect Energy, work and power outcomes to exam-style questions, flashcards, and revision notes for Energy, work and power.

Revision tools