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Energy Transfer DiagramsEnergy Transfer Diagrams
Starter Activity (back of jotters):Starter Activity (back of jotters):1)1) What are the 10 types of energy?What are the 10 types of energy?2)2) Draw an energy flow diagram for an ipodDraw an energy flow diagram for an ipod
Chemical potentialenergy in food
Kinetic Energy
Sound Energy
Heat Energy
Energy ChangesWhat are the energy changes for a person on a tricycle?
What is wasted and what is useful energy?
Battery powered television set
Chemical potentialenergy in battery
Electrical Energy
Light Energy
Sound Energy
Heat Energy
What is wasted and what is useful energy?
Energy Diagram
500 J
200 J
300 J
Electricity
Heat
Light
We show how energy is transferred using Energy Diagrams
Energy Diagrams
500 J
200 J
300 JWhat’s wrong with this Energy diagram?
What’s wrong with this Energy diagram?
Electricity
Heat
Light
Accurate Energy Diagrams
10J electrical energy in
1J useful light energy out
9J wasted heat energy out
Filament bulb
The total energy in is equal to the total energy out
Draw an Energy diagram for the following on graph paper.
1) A lawnmower.
Input: 100J electrical
Output: 70J useful kinetic30J wasted heat
2) A wood fireplace
Input: 100J chemical potential
Output: 40J useful light40J useful heat20J wasted sound
10J electrical energy in
1J useful light energy out
9J wasted heat energy out
10J electricalenergy in
4J useful light energy out
Filament bulb
Energy efficient bulb6 J wasted heat energy out
Which light bulb would you buy and why?
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”
Energy LabelsMachines have labels which
tell customers how efficient
their appliance (washing machine/TV
etc) is.
Why would we want to know this?
