lesson 2 sankey diagrams and efficiency
Post on 08-Nov-2014
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Do now!Can you remember all the
“Types of energy” we looked at last lesson?
Energy transfer (change)
A lamp turns electrical energy into heat and light energy
Energy transfer (change)
electrical light + heat
Sankey Diagram
A Sankey diagram helps to show how much light and heat energy is produced
Sankey Diagram
The thickness of each arrow is drawn to scale to show the amount of energy
Sankey Diagram
Notice that the total amount of energy before is equal to the total amount of energy after (conservation of energy)
Efficiency
Although the total energy out is the same, not all of it is useful.
Efficiency
Efficiency is defined as
Efficiency (%) = useful energy output x 100
total energy input
Efficiency
Efficiency is defined as
Efficiency (%) = useful energy output x 100
total energy input
Can you copy this (with title) please?
Example
Efficiency = 75 x 100 = 15%
500
Energy efficient light bulb
Efficiency = 75 x 100 = 75%
100
Energy efficient light bulb
Efficiency = 75 x 100 = 75%
100 That’s much better!
More complex examples
Let’s try some questions!
Stick the sheet into your books and answer the questions
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