1. Energy Transfer Diagrams
Starter Activity (back of jotters):
What are the 10 types of energy?
Draw an energy flow diagram for an ipod

2. Energy Changes What is wasted and what is useful energy?
What are the energy changes for a person on a tricycle?
Kinetic Energy
Sound Energy
Heat Energy
Chemical potential
energy in food
What is wasted and what is useful energy?

3. Battery powered television set
Electrical Energy
Light Energy
Sound Energy
Chemical potential
energy in battery
Heat Energy
What is wasted and what is useful energy?

4. Energy Diagram We show how energy is transferred using Energy Diagrams
300 J
Heat
Electricity
500 J
Light
200 J

5. What’s wrong with this Energy diagram?
Energy Diagrams
What’s wrong with this Energy diagram?
300 J
Heat
Electricity
500 J
200 J
Light

6. Accurate Energy Diagrams
Filament bulb
9J wasted heat
energy out
10J electrical energy in
1J useful light
energy out
The total energy in is equal to
the total energy out

8. Draw an Energy diagram for the following on graph paper.
1) A lawnmower.
Input: 100J electrical
Output: 70J useful kinetic
30J wasted heat
2) A wood fireplace
Input: 100J chemical potential
Output: 40J useful light
40J useful heat
20J wasted sound

9. Which light bulb would you buy and why?
Filament bulb
9J wasted heat
energy out
10J electrical energy in
1J useful light
energy out
Energy efficient bulb
6 J wasted heat
energy out
4J useful light
energy out
10J electrical
energy in

10. Energy Efficiency
An Energy Diagram can tell us how much useful and wasted energy we will get from a device like a bulb. The more useful energy we can get out of it, the better.
This is called the “energy efficiency”

11. Energy Labels Machines have labels which tell customers how efficient
their appliance (washing machine/TV
etc) is.
Why would we want to know this?