Transcript 17.3 Generators and Motors

Simulation things to note…
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Part A: your arrow tip = red part of needles
Part B: you can change battery voltage on the
actual battery
Part C: circuit = what is on your screen, when
you click on “polarity” = “flip polarity”
Voltage
Current
Resistance
Chapter 17
Electric Motors and Generators
Electric Motors and Generators
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Electrical energy: energy from moving
electrical charge
Mechanical energy: energy due to motion or
position
Motors: transform electrical energy into
mechanical energy
Generators: transform mechanical energy into
electrical energy
More Vocabulary
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Rotor – a piece that rotates in a motor
Commutator – a device that can reverse the
flow of electric current
Electric Motors
Motors have three parts:
1.
A rotor with magnets that
alternate.
2.
One or more fixed magnets
around the rotor.
3.
A commutator that switches
the direction of current to
keep the rotor spinning.
Electric motors
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Around the edge of a rotor
are several magnets, their
alternating north and
south poles facing out.
Electric motors
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To make the rotor spin,
bring a permanent magnet
close to its edge.
The free magnet attracts
one of the magnets in the
disk and repels the next
one.
The disk is a “rotor”
because it rotates.
Electric motors
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In a working electric motor, an
electromagnet replaces the magnet you
reversed with your fingers.
As the rotor spins, a commutator
reverses the direction of the current in
the electromagnet.
Electromagnetic Induction
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Electromagnetic induction: a moving magnet
produces a current in a coil of wire
Generators use electromagnetic induction to create
electricity
Battery Run Electric Motors
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An electric motor that runs from batteries has the same
three parts: rotating part, fixed magnets, and a
commutator.
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The permanent magnets are on the outside, and the
electromagnets turn in the rotor.
Commutator
Permanent magnets
Generating Electricity
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A generator converts mechanical energy into
electrical energy using the law of induction.
 As long as the disk is spinning, there is a changing
magnetic field through the coil and electric current is
created.
Exit Question!
The diagram below represents the rotor of an electric
motor. To cause the rotor to turn in a counter-clockwise
direction, the north pole of a magnet should be placed at
position: