Download Science 9: Unit D – Electrical Principles and Technologies

Science 9: Unit D – Electrical
Principles and Technologies
Topic 6: Generators and Motors
The History of Electromagnetism
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Electricity and magnetism are connected. You
can use electricity to make magnets and you
can use magnets to make electricity flow
through wires. Using both electricity and
magnets creates such things as electric
motors which power electric cars, and
electric generating plants which create
huge amounts of energy. This connection
was first discovered by Michael Faraday in
the 1800s.
Using Electricity to make a
Magnet
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We can make a magnet using wire, a source of
electricity (eg. Battery/cell), and a piece of
metal such as an iron nail. Magnets created this
way are called electromagnets.
1. Hook up a wire to the negative end of the
terminal on a battery.
2. Wrap the wire around the piece of iron so that it
forms a coil.
3. Take the other end of the wire and hook it up to
the other terminal of the battery.
4. Test out the electromagnet by bringing it close to
pieces of metal such as paperclips. It should pick
them up.
Electric Motors
An electric motor is a device that takes in electrical energy
and changes it to kinetic energy.
 Electric motors are used in many different things from toy
cars to electric fans and can openers.
 An electric motor works through electromagnetism. An
electric current is passed into a circuit. The circuit passes
through a coil of wire making an electromagnet. When the
electromagnet is activated by electricity it becomes a
magnet and reacts with permanent magnets on the motor.
 The magnets repel each other and the motor begins to
spin, electrical energy is now turned into moving energy.
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Induction: Using Magnet to Make Electricity
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A moving magnet will generate an electric
current in a nearby piece of metal wire.
Also moving the wire in the presence of a
magnet will cause the same effect.
Generators
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Generators work by taking in some kind of
mechanical energy and changing and storing
it as electrical energy. A generator basically
works in reverse order from an electric
motor. Moving energy is supplied which
causes permanent magnets to move which
cause an electric current to run through the
wire.
A generator can either be used to supply
electricity to a load (example: to a bicycle
headlight) or to a battery to be stored for
later use (battery chargers).
Power-Plants Use Generators on a
GIGANTIC Scale
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A power-plant is basically a large
generator with large, powerful magnets,
and large coils of wire. To rotate the coils
of wire (the turbines) a large mechanical
force is needed. Different power-plants
use different sources of mechanical
energy to do this:
What are the Options for
Electricity Generating Power-Plants?
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Fossil Fuel - Burning coal to produce steam
energy – Alberta
Wind turbines – Southern Alberta
Hydroelectric (moving water moves
turbines) – Mountains, Ontario anywhere
where there’s waterfalls, fast moving water.
Nuclear Power – Breaking up a small
amount of uranium unleashes a large amount
of heat which can be used to move steam
turbines.
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1. Compare
and contrast electrical motors and
Homework
generators.
2. Who first discovered that electricity and
magnetism were connected. When? Explain the
importance this discovery to our modern world.
3. What’s a magnetic domain?
◦ B) What types of materials have magnetic domains?
◦ C) How are magnetic domains aligned when the material is
not magnetized?
4. Define and explain the term induction.
5. (p. 317: #2)
6. (p. 317: #5)
7. BLM 4-14