This deep dive covers Sankey Diagrams 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 3 of 13 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 3 of 13
Practice
19 questions
Recall
4 flashcards
🔄 Sankey Diagrams
A Sankey diagram is a visual tool for showing energy transfers. The width of each arrow is proportional to the amount of energy it represents.
- A single thick arrow on the left represents total input energy
- An arrow pointing to the right represents useful output energy
- Arrows pointing downward (or in other directions) represent wasted energy
- The total width of all output arrows must equal the width of the input arrow (conservation of energy)
For example, a car engine with 25% efficiency would have a Sankey diagram where 25% of the arrow width points to "kinetic energy" and 75% points downward to "thermal energy" (heat from combustion and friction).
Sankey diagrams are useful because you can see at a glance how much energy is wasted relative to the useful output — the bigger the downward arrows, the less efficient the device.
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?
Explain one method that can be used to reduce unwanted energy transfers in a machine and state how it reduces waste.
Quick Recall Flashcards
19 questions on Efficiency — practise free
Instant marking, adaptive difficulty, and 4 spaced repetition flashcards. Free until your GCSEs.
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