EnergyExam Focus

Exam Focus: Efficiency

Part of EfficiencyGCSE Physics

This exam focus covers Exam Focus: Efficiency within Efficiency for GCSE Physics. Revise Efficiency in Energy for GCSE Physics with 19 exam-style questions and 4 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 11 of 13 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.

Topic position

Section 11 of 13

Practice

19 questions

Recall

4 flashcards

🎯 Exam Focus: Efficiency

How this topic appears in exams:

  • Calculation (2-3 marks): Calculate efficiency as a decimal or percentage from given input/output values
  • Rearranging (2 marks): Find useful output or total input given the efficiency and one energy value
  • Sankey diagram (3-4 marks): Draw or complete a Sankey diagram with correct proportional arrow widths
  • Interpretation (2 marks): Read an efficiency value from a Sankey diagram and identify which device is more efficient
  • Explain energy dissipation (3 marks): Describe how energy is wasted and why it cannot be easily recovered

Keep building this topic

Read this section alongside the surrounding pages in Efficiency. That gives you the full topic sequence instead of a single isolated revision point.

Practice Questions for Efficiency

Which equation correctly defines efficiency?

  • A. efficiency = total input energy / useful output energy
  • B. efficiency = useful output energy transfer / total input energy transfer
  • C. efficiency = wasted energy / total input energy
  • D. efficiency = total input energy / wasted energy
1 markfoundation

Explain one method that can be used to reduce unwanted energy transfers in a machine and state how it reduces waste.

2 marksstandard

Quick Recall Flashcards

As a decimal
0.85 (between 0 and 1)
As a percentage
85% (multiply decimal by 100)

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