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
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.
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.