Lesson: Sankey Diagrams

In this lesson, we will learn how to correctly draw and interpret Sankey diagrams for processes that involve the transfer of energy.

Video

10:25

Sample Question Videos

01:23
02:39

Worksheet: 9 Questions • 2 Videos

Q1:

The image shows a Sankey diagram for a light bulb that has been drawn incorrectly. In which of the following ways has the diagram been drawn incorrectly?

The value represented by one square of the diagram is not consistent.
1 square of a Sankey diagram should always represent 1 watt or 1 joule.
Sankey diagrams can only be used for energy, not power.
The two output arrows both represent 20 W, but they are of different widths.
The total output power is not equal to the total input power.

Q2:

Diagram (a) is a Sankey diagram of a 1.8 kW kettle. Diagram (b) is a Sankey diagram of an 80 W light bulb.

Which device is more efficient?

What is the efficiency of the kettle?

What is the efficiency of the light bulb?

Q3:

The image shows Sankey diagrams for four different processes.

Which process is the most efficient?

Which process is the least efficient?

Preview