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Unit 12: Alternative Energy Page 19 of 31
giant chasm between the free propeller turns. If you attach the
electrons (electrons knocked out of propeller to a motor shaft, the
its shell) and bound electrons motor will rotate, which has coils of
(electrons attached to an atom). wire and magnets inside. The
Electrons can be either free or faster the shaft turns, the more the
attached, but it costs a certain magnets create an electrical
amount of energy to go either way current.
(like a toll both).
The electricity to power your
When sunlight hits the computer, your lights, your air
semiconductor material in the solar conditioning, your radio or
cell, some of the electrons get whatever, comes from spinning
enough energy to jump the gap magnets or wires! (Refer to Unit 11
and get knocked out of their shell for more detail about how moving
to become free electrons. The free magnets create electricity.)
electrons zip through the material
and create a low of electrons. Does it really matter what angle
When the sun goes down, there's the solar cell makes with the
no source of energy for electrons incoming sunlight? If so, does it
to get knocked out of orbit, so they matter much? When the sun moves
stay put until sunrise. across the sky, solar cells on a
house receive different amounts of
Wind and sunlight. You’re going to find out
Water Power exactly how much this varies by
building your own solar vehicles.
Believe it or not,
most of the Battery-Free Radios?
electricity you use comes from
moving magnets around coils of A crystal radio is
wire! Wind turbines spin big coils of among the simplest of
wire around very powerful magnets radio receivers -
(or very powerful magnets around there’s no battery or
big coils of wire) by capturing the power source, and nearly no
flow. moving parts. The source of power
comes directly from the radio
Here's how it works: when a waves themselves.
propeller is placed in a moving fluid
(like the water from your sink), the The crystal radio turns the radio
signal directly into a signal that the
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