Physics · KS3 Y9 · Energy

Sankey diagrams

Sankey diagramsFree3:34Heddy Score 3 of 7, below the standard

What you need to know

  • In a Sankey diagram the width of each arrow shows how much energy it represents.
  • Useful energy carries straight on, while wasted energy (usually by heating) branches downwards.
  • The arrows leaving add up to the arrow going in, which shows energy is conserved.
  • Efficiency is useful energy output divided by total energy input, so a value nearer 1 means a better device.
  • A worked television example reads values off a grid and gives an efficiency of 0.8, compared with 0.2 for a filament bulb.

In this clip

Runs 3:34, from 0:00 to 3:34 of the full video.

Heddy Score3/7, Below the standard
See the seven stars
  • Trusted source · passed. The creator's own upload, live and playable here.
  • On the map · not judged yet. A teacher watched it: it mainly teaches this map topic.
  • Spec-true · not judged yet. Accurate, and right for the current UK specification.
  • Focused · passed. One idea, short enough to watch in one go.
  • Accessible · passed. Good captions, clear sound and pictures.
  • Safe for children · not judged yet. Right for 11 to 16 year olds, with no sales pitch.
  • Proven · not judged yet. Earned from our students: they learn from it, find it helpful and watch it to the end.
★ passed · ☆ pending · ✕ failed
Our students

Not enough students yet

Our own students' answers. These are what move ★7 Proven.
On YouTube

179K views · 1.49K likes · Ace Physics and Maths 18.8K subscribers

As reported by YouTube on 2026-11-02. Not part of the Heddy Score.
How the Heddy Score works

Why we picked it

A short, clear walkthrough of reading Sankey diagrams with two worked efficiency examples.

Ace Physics and Maths on YouTubechecked 2026-10-22

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