Energy transformation diagrams

Question 1

What are Sankey diagrams used for?

Answer 1

To make it easy to see at a glance, how much of the total energy in is being usefully employed compared with how much is being wasted.

Question 2

What does the thicker the arrow mean?

Answer 2

The more energy it represents.

Question 3

What does a Sankey diagram look like?

Answer 3

A big thick arrow going in, then several smaller arrows doing off it to show the different energy transformations taking place.

Question 4

What are the two types of Sankey diagrams?

Answer 4

• A sketch.

- A detailed diagram, with the width of each arrow being proportional to the number of joules it represents.

Question 5

What sort of question would you be asked in an exam with a sketch Sankey diagram?

Answer 5

To compare two different devices and say which is more efficient (biggest useful energy arrows).

Question 6

What sort of question would you be asked in an exam with a detailed Sankey diagram?

Answer 6

Calculating the efficiency, or filling in the gaps.