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.
🎯 Exam Focus: Efficiency
This topic is examined in Edexcel 1PH0/1 (Paper 1). Edexcel questions often present Sankey diagrams or data tables comparing two appliances and ask you to calculate efficiency or evaluate which device is more cost-effective. The "Suggest" command word is used for questions asking why efficiency cannot reach 100% in a given real context.
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
Practice questions for Efficiency
Which equation correctly defines efficiency?
Explain one method that can be used to reduce unwanted energy transfers in a machine and state how it reduces waste.