Download Making an Electric Current with Magnets

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Date
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Lesson Outline
LESSON 3
Making an Electric Current with Magnets
A. Magnets and Wire Loops
Electric Current
1. Magnetic fields can produce
moves in a wire loop that is part of a(n)
when a magnet
Closed
electric
Stops
circuit; if the magnet stops moving, the current
.
2. Another way an electric current can be produced is when a(n)
Coil
of wire moves through a(n)
Magnetic field
.
B. Electric Generators
Generator
1. An electric
is a device that uses a magnetic field to
Mechanical
change
energy to electrical energy.
2. Electric generators differ from batteries because batteries produce
Direct
current, which is an electric current that flows in only
Direction
one
.
Alternating
Direction
3. Most electric generators produce
electric current that changes
current, which is an
in a regular pattern.
Commutator
a(n)
that prevents the current from changing direction.
C. Generators and Power Plants
Coils
1. Increasing the number of
Loops
and the number of
in each coil increases the amount of electric current
a generator produces.
2. A generator transforms
Electrical
Mechanical
energy to
energy.
a. The source of mechanical energy in some power plants comes from high-pressure
jets of steam from
b.
Hydroelectric
Boiling
water.
power plants use the mechanical energy from falling
water.
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Magnetism
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
4. An electric generator can produce a direct current if the generator uses
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Lesson Outline continued
3. In electrical power plants, a generator is usually is connected to
a(n)
Turbine
.
Shaft
a. A turbine is a(n)
Spins
with a set of blades that
when a pressurized fluid strikes the blades.
Mechanical
b. A turbine transfers
energy to the generator.
D. Transformers—Changing Voltage
Alternating
1. A transformer changes the voltage of a(n)
Coils
2. A transformer contains two
Iron
a(n)
current.
of wire wrapped around
core.
a. An alternating electric current in the primary coil produces a changing
Magnetic Field
around the core.
Alternating
b. This changing magnetic field produces a(n)
current
in the secondary coil.
3. If the input voltage to the primary coil increases, then the output voltage from the
secondary coil
Increases
.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
E. Electrical Energy—From a Power Plant to Your Home
Step-up
1.
current that is produced by
transformers increase the voltage of the alternating
Generators
2. Before electric current enters your home, a(n)
in electrical power plants.
Step-down
transformer decreases the voltage of the current to
Magnetism
120 volts
.
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