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.