13 April, 2015
Energy Transformations
Objectives
Understand that energy can change form and be able
to draw diagrams to represent this.
HSW: AF3: Select appropriate methods for presenting scientific data.
Used before in: lesson 1 – Energy Types
Will use again in:
PLTS:
Used before in:
Will use again in:
Keywords
Energy, Transfer, Transformation, Sankey, Useful, Wasted.
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Outcomes:
All students should be able to:
• Draw energy transfer diagrams that describe energy
transformations.
• Interpret Sankey diagrams and label useful and wasted energy.
Most students should be able to:
• Use Sankey diagrams to work out the amount of energy
transformed by a device into different types.
• Draw accurate Sankey diagrams using graph paper.
Some students should be able to:
• Use a Sankey diagram to calculate the efficiency of a device.
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Energy transfer in a television
An energy transfer diagram shows the input and output
energies for a device. This includes all the useful and wasted
forms of energy.
For example, in a television:
light
electrical
sound
heat
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Energy transfer in a radio
What are the main energy transfers in a radio?
(Don’t forget the wasted energy.)
electrical
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sound
heat
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Energy transfer in a car engine
What are the main energy transfers in a car engine?
(Don’t forget the wasted energy.)
kinetic
chemical
sound
heat
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Identifying energy transfers
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How can we represent energy transfers?
All the energy transfers
(useful and wasted) that
are associated with a
device can be represented
by a Sankey diagram.
A Sankey diagram uses
arrows to represent all the
output energies.
Filament light bulb
100 J
10 J
electrical
light
energy
energy
(input)
(output)
90 J
heat energy
(wasted)
The thickness of each
arrow is proportional to the
amount of energy involved
at that stage.
Energy efficient light bulb
20 J
10 J
electrical
light
energy
energy
(input)
10 J (output)
heat energy
How does the energy use in
(wasted)
these light bulbs compare?
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TASKS
ALL
1) Use the keywords to copy and complete the following:
• Energy ………… diagrams can show how energy moves from one
place to another and ……… type. They can also show the
useful and …… energies.
• Sankey Diagrams show ……… that represent the amount of
energy being transformed so that you can easily see the
…………. of useful and wasted energy and calculate the ………….
of a device.
wasted
transfer
efficiency
arrows
changes
percentage
MOST
2) Draw an energy transfer diagram for a car engine and label the useful
and wasted energies.
Use the following words to help: Chemical, Heat, Sound, Kinetic
3) Do questions 1 – 3 on pages 46 & 47 of Milner Text Book
SOME
4) Do question 4 and 5 on page 47 of the Milner Text book and calculate
the efficiency of each engine. Can you think of a good way of displaying
this data?
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Plenary – The Big Q: How efficient is a Power Station?
•
•
•
Describe the following energy transfer using appropriate diagrams and
calculations.
Burning Coal produces 100 Mega Joules of Energy.
65 Mega Joules is transformed into electrical energy in a power station but
the rest is wasted as heat.
All students should be able to:
• Draw energy transfer diagrams that describe energy transformations.
C
Most students should be able to:
• Use Sankey diagrams to work out the amount of energy transformed by a
device into different types.
• Draw accurate Sankey diagrams using graph paper. B
Some students should be able to:
• Use a Sankey diagram to calculate the efficiency of a device.
•
A
Now swap with your partner and mark it.
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