Transcript Science 9: Unit D: Topic 4 Notes

Science 9: Unit D:
Topic 4 Notes
The Energy Connection
What exactly is energy?
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Energy – is the ability to do work.
Much of our energy is supplied by current
electricity.
This electrical energy is useful because it is
convenient to move large distances, where
it is changed to heat energy (toaster), light
energy (bulbs), or mechanical energy
(electric motor).
Thermal Energy to Electrical Energy
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From Science 7 – thermal energy = heat.
A thermocouple is a device which converts
heat to electrical energy.
Thermocouples are made up of a loop of
two wires made of two different metals.
When they experience a temperature
change, they generate a voltage, which in
turn produces a weak electric current. This
is called the Seebeck Effect.
Thermo-Electric Generators
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A T.E. generator is a device which transforms
heat energy into useful, useable electrical
energy. An example of a TEG is a thermopile.
A thermopile is a collection of thermocouples
connected in series or in parallel to amplify the
amount of electricity that is produced. The
same principles work here. See fig 4.25 on p.
295.
Piezoelectric Effect
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Movement or vibration (mechanical energy)
caused by an electrical current.
A special crystal that can expand or
contract when experiencing a current.
When touching some other object, the
contact can cause sound waves to form,
like in greeting cards. This technology is
also used in electric watches.
Electrical to Light Energy
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LEDs – Light emitting diodes – a
semiconductor chip glows when a current is
passed through it. This arrangement is
much more efficient than traditional
incandescent and even fluorescent lights.
Light to Electrical Energy
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Photovoltaic Effect – By shining high
intensity light on semiconductors, electrons
are ‘shaken loose’ and flow freely through a
metal wire where they will reach the load.
The PV effect has been used to create PV
or solar cells, and solar arrays which power
everything from calculators to the
International Space Station.
Bioelectricity: The Electric Eel
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Not really an eel, but a
knife-fish.
Contains specialized
muscle cells called
electroplaques which,
in total, can produce a
voltage of 600 V.
This voltage produces
a large enough electric
shock to stun or kill its
prey.