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Name
Date
Magnetism and Its Uses
Section 2 Electricity and Magnetism
Scan the headings, figures, and captions in Section 2 of your text.
Write two questions that come to mind.
1. Accept all reasonable responses.
2.
Review
Vocabulary Define electric current to show its scientific meaning.
electric current
the flow of electric charges in a wire or any conductor
New
Vocabulary Use your book or a dictionary to define the following key terms.
electromagnetic force
the attractive or repulsive force between electric charges and
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
magnets
electromagnetism
solenoid
the interaction between electric charges and magnets
a single wire wrapped into a cylindrical wire coil creating a strong
magnetic field
electromagnet
a temporary magnet made by wrapping a wire coil carrying a
current around an iron core
galvanometer
device that uses an electromagnet to measure electric current
electric motor
device that changes electrical energy into mechanical energy
Magnetism and Its Uses
83
Name
Date
Section 2 Electricity and Magnetism
(continued)
Electric Current
and Magnetism,
Electromagnets
Evaluate the magnetic fields that surround two identical pieces of
wire carrying the same electric current. One wire is straight, and
the other wire is coiled into a solenoid.
I found this information
on page
.
Accept all reasonable responses. The magnetic field surrounding
SE, pp. 209–210
RE, pp. 113–114
the solenoid is much stronger than the magnetic field
surrounding the straight wire. The magnetic fields of the loops in
the solenoid combine to make the total magnetic field stronger.
Using
Electromagnets
I found this information
on page
.
SE, p. 212
RE, p. 115
Sequence the steps in the explanation of how electromagnets
make sound when you listen to a CD. Some terms from the word
bank may be used more than once.
amount
current
direction
electromagnet
magnetic field
repelled
reproduces
voltage
The voltage
produces an electric
electromagnet next to the speaker cone.
current
The CD contains information that changes the
of current and its direction .
in the
amount
The changing electric current changes the direction and strength
of the magnetic field around the electromagnet.
The electromagnet is attracted to or
permenant magnet.
repelled
by the
The moving electromagnet vibrates the speaker cone and
reproduces the sound recorded on the CD.
84
Magnetism and Its Uses
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
The CD player produces a voltage .
Name
Date
Section 2 Electricity and Magnetism
I found this information
on page
.
SE, p. 213
RE, p. 116
Students can look
around the classroom
or think about various
rooms in their homes
to find electric motors.
(continued)
Model and label a galvanometer and describe how it works.
An electromagnet is located between
the poles of a permanent magnet and
is connected to a small spring. The
Accept all reasonable
variations with
accurate labels.
electromagnet rotates until the
force applied by the spring is balanced
with the magnetic forces on the
electromagnet. A needle is attached to
the electromagnet so it turns.
Electric Motors
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
I found this information
on page
.
SE, p. 214
RE, p. 117
Advanced students
may describe a simple
electric motor that
includes these parts:
coils, brushes,
commutator, and a
permanent magnet.
Sequence the steps an electric motor uses to change electrical
energy to mechanical energy. Make a sketch and label the motor.
1. Current flowing through a wire
creates a magnetic field around
the wire.
2. A nearby magnet causes the wire
to be pushed or pulled, depending
Accept all reasonable
variations with
accurate labels.
on the direction the current flows.
3. Some of the electric energy from
the current is changed into the
kinetic energy of moving the wire.
S YNTHESIZE I T
How can electromagnets be useful to humans?
Accept all reasonable responses. Electromagnets are useful because they are temporary
magnets that can be turned on and off.
Magnetism and Its Uses
85