Transcript Slide 1

P1.2.1 Energy and
efficiency
Mr D Powell
Connection
•
•
•
Connect your learning to the
content of the lesson
Share the process by which the
learning will actually take place
Explore the outcomes of the
learning, emphasising why this will
be beneficial for the learner
Demonstration
• Use formative feedback – Assessment for
Learning
• Vary the groupings within the classroom
for the purpose of learning – individual;
pair; group/team; friendship; teacher
selected; single sex; mixed sex
• Offer different ways for the students to
demonstrate their understanding
• Allow the students to “show off” their
learning
Activation
Consolidation
• Construct problem-solving
challenges for the students
• Use a multi-sensory approach – VAK
• Promote a language of learning to
enable the students to talk about
their progress or obstacles to it
• Learning as an active process, so the
students aren’t passive receptors
• Structure active reflection on the lesson
content and the process of learning
• Seek transfer between “subjects”
• Review the learning from this lesson and
preview the learning for the next
• Promote ways in which the students will
remember
• A “news broadcast” approach to learning
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Quick Summary....
P1.2.1 Energy and efficiency
a) Energy can be transferred usefully, stored, or dissipated, but
cannot be created or destroyed.
b) When energy is transferred only part of it may be usefully
transferred, the rest is ‘wasted’.
c) Wasted energy is eventually transferred to the surroundings,
which become warmer. The wasted energy becomes increasingly
spread out and so becomes less useful.
You should be able to compare the efficiency and cost
effectiveness of methods used to reduce ‘energy consumption’
■ describe the energy transfers and the main energy wastages
that occur with a range of appliances
■ interpret and draw a Sankey diagram.
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What am I thinking of.....
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Make a table listing the items in the diagram and link any energy
changes you think apply;
Pendulum Kinetic -> GPE-> Kinetic
ELECTRIC
TORCH
PENDULUM
CANDLE
SPRING
HiFi
Torch
Electrical -> Heat -> Light
....
....
Gravitational Potential Energy
Chemical Potential Energy
Elastic Potential Energy
Heat (Thermal)
Light
Sound
Kinetic
Electrical
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Energy Changes...

A weight is raised using a winch driven by an electric motor. Use the
forms of energy listed below to complete the energy flow diagram.
1.
2.
3.
4.
5.
chemical energy
Chemical Energy
electrical energy
kinetic energy
gravitational potential energy
sound energy and thermal
energy due to friction
thermal energy due to resistance
of the wires
A.
Electrical Energy
B.
Kinetic Energy
D.
Gravitational PE
C.
Thermal wasted
E.
Sound
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More Energy Changes...

A falling weight can be used to light a lamp using a winch and a generator.
1.
2.
3.
4.
5.
electrical energy
kinetic energy
gravitational potential energy
light energy
sound and thermal energy due to
friction
6. thermal energy due to resistance of
the wires and lamp
chemical energy
GPE
A.
Kinetic
B.
Electrical
D.
Light
Thermal/ Sound
wasted
C.
Thermal in wires
wasted
E.
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Energy Transforms
 Use the pictures on this page to
inspire you to talk about the
energy changes on
rollercoaster's.
 Write an article (with diagrams)
designed for a magazine aimed at
GCSE / Year 9 pupils who need to
know about all the energy
changes involved in the
rollercoaster.
Possible Key Words....
Kinetic, GPE, Friction, Thermal, Useful,
Wasted, sound, velocity, acceleration...
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Efficiency Calculations
Can you work out the missing numbers for this table...
Efficiency =
Useful Energy
Energy Supplied
Device
Energy supplied
(in joules)
Useful energy
(in joules)
Waste energy
(in joules)
Electric motor
500
150
350
Desk lamp
300
60
240
0.2
PC monitor
5000
500
4500
0.1
Microwave
oven
50 000
40,000
10,000
0.80
20
30
0.40
Torch lamp
50
Efficiency
0.3
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Sankey Diagrams
Sankey diagrams summarise all
the energy transfers taking
place in a process. The thicker
the line or arrow, the greater
the amount of energy involved.
The Sankey diagram for an
electric lamp below shows that
most of the electrical energy is
transferred as heat rather than
light.
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Efficiency?

How do the sankey diagrams
show which light bulb is more
efficient? Describe two
devices and diagrams which
explain this point.
Ordinary electric lamps contain a thin
metal filament that glows when
electricity passes through it. However,
most of the electrical energy is
transferred as heat energy instead of
light energy.
Modern energy-saving lamps work in
a different way. They transfer a
greater proportion of electrical
energy as light energy.
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Accurate Sankey Diagrams
Notice how this diagram is completed to scale. The vertical
part of the scale is 2 squares = 10J of energy. Try and draw
these 4 in a similar way on one sheet of graph paper.
Torch with
Chemical -> Light
5J & Heat 95J
Car with Chemical > Kinetic 25J &
Heat 75J
Bunsen Burner
with Chemical ->
Heat 85J, Light 10J,
Sound 5J
Hairdryer ->
Electrical -> Sound
5J, Heat 20J,
Kinetic 75J
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Sankey Diagrams

This diagram represents energy transfer by the drill
motor. The manufacturer claims the drill motor has
an efficiency of 0.35. The drill motor is supplied with
3000 J of electrical energy when the hole is drilled.
1.
What form of energy does A represent?
2.
What does B represent and what forms of energy
are included in it?
3.
What is the useful energy transferred by the drill
motor used for?
4.
What is the useful energy from the drill motor?
5.
What is the energy wasted by the drill?
1.
2.
3.
4.
5.
Electrical
wasted thermal / sound
Kinetic
0.35x 3000J = 1050J
(1-0.35) x 3000J = 1950J
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Further notes...
P1.2.1 Energy and efficiency – Video Sheet
Food Chains

A good example of
energy which is lost to
the surroundings is a
food chain.

Use this graphic and
your own ideas to
present this with
examples of real food
chains. Explain clearly
where the energy goes
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Food Chains



growth
heat
locked into
cells





growth
heat
kinetic
sound
excretion





growth
heat
kinetic
sound
excretion
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US Energy uses / wastage 2002
Talking point...
What can you say about energy use in the US in 2002?
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Summary Questions
1.
Energy can _________
transformed from one form into other forms.
2.
Energy can be ___________
transferred from one place to another place.
3.
Energy cannot be ________
created or __________.
destroyed
4.
_______
useful energy is energy in the place we want
Stored or _______
it and in the form we need it.
5.
_______
wasted energy is energy that is not useful.
6.
Useful energy and wasted energy both end up being
transferred to the ____________
surroundings which become warmer.
7.
spreads out, it gets more and more difficult to
As energy _______
use for further energy transfers.
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Get thinking?
“tonight an in-depth look at what
each of us can do to help
conserve electricity”
Where has the energy gone?
What happens here....
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Which uses the lowest energy...
Can you sort these into a rough order....
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Which uses the lowest energy...
Can you sort these into an order....
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How much energy do appliances use....
Make a note of some of these appliances and their energy uses. Write a short
sentence to explain why they might be Power hungry....
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Electrical Devices
 In a pair list all the
electrical devices
you can see.







Cooker
Coffee pot
Kettle
Microwave
Food Processor
Radio
Washing
Machine
 Iron
 Hoover
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Electrical Devices
Consider the following things
for each item you see;
1.
Mains or Battery
powered?
2.
Useful Energy in
3.
Wasted Energy
4.
How is efficiency
improved?
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Can you identify forms of useful energy and wasted energy in
different household devices?
Device
Battery or
mains?
Useful
energy
Energy
wasted
Thermal/
Electric
kettle
M
Thermal
Computer
M
Electrical /
Light
Thermal
CPU fans can run slower to
save energy, monitor turns
off
Portable CD
player
B
Kinetic /
Sound
Thermal
Auto off switch, motor only
runs when you press play
Lamp
M
Light
Thermal
Use special efficient bulbs
Electric bell
B
Kinetic /
Sound
Thermal
Current only flows when the
button is pressed.
Sound
Efficiency
Lid put on top
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Efficiency?
Now you have thought about
these devices in an “energy”
way do the following;
1.
2.
On a double page spread
draw a bubble for each one
with their names i..e “Laptop
PC”
Draw out spider lines and
describe or annotate any
ideas you have for how they
can be modified /redesigned
to become more efficient and
reduce the energy they waste
3.
Estimate a Sankey Diagram...
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Efficiency?
Can you complete your own
estimated Sankey energy
diagrams for each device you
studied today.
You nee to list input energy,
useful out energy, wasted
energy & estimate the
quantities in joules.
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How can you explain these things...
a) Energy can be transferred usefully, stored, or
dissipated, but cannot be created or destroyed.
b) When energy is transferred only part of it may be
usefully transferred, the rest is ‘wasted’.
c) Wasted energy is eventually transferred to the
surroundings, which become warmer. The wasted energy
becomes increasingly spread out and so becomes less
useful.
You should be able to compare the efficiency and cost
effectiveness of methods used to reduce ‘energy
consumption’
■ describe the energy transfers and the main energy
wastages that occur with a range of appliances
■ interpret and draw a Sankey diagram.
P1.2.1 Energy and efficiency
Lifting a Weight
Lowering a Weight
Gravitational Energy
chemical energy
A.
A.
B.
B.
C.
C.
D.
E.
D.
E.
P1.2.1 Energy and efficiency - worksheet
Device
Energy
supplied
(in
joules)
Useful
energy (in
joules)
Electric
motor
500
150
Desk lamp
300
PC
monitor
Microwave
oven
Waste
energy
(in joules)
Efficiency
240
500
4500
50 000
Torch lamp
0.80
20
0.40
Device
Energy
supplied
(in
joules)
Useful
energy
(in
joules)
Electric
motor
500
150
Desk lamp
300
PC
monitor
Microwave
oven
Torch
lamp
Waste
energy
(in
joules)
Efficiency
240
500
4500
50 000
0.80
20
0.40
1.
Energy can _________
forms.
Energy can be ___________ from one place to
another place.
2.
Energy can be ___________ from one place to
another place.
3.
Energy cannot be ________ or __________.
3.
Energy cannot be ________ or __________.
4.
_______ or _______ energy is energy in the place
we want it and in the form we need it.
4.
_______ or _______ energy is energy in the place
we want it and in the form we need it.
5.
_______ energy is energy that is not useful.
5.
_______ energy is energy that is not useful.
6.
Useful energy and wasted energy both end up
being transferred to the ____________ which
become warmer.
6.
Useful energy and wasted energy both end up
being transferred to the ____________ which
become warmer.
7.
As energy _______ out, it gets more and more
difficult to use for further energy transfers.
7.
As energy _______ out, it gets more and more
difficult to use for further energy transfers.
1.
Energy can _________
forms.
2.
from one form into other
from one form into other
P1.2.1 Energy and efficiency - worksheet