Electromagnetism Electromagnetism

Chapter Highlights
Vocabulary
magnet (p. 454)
poles (p. 454)
magnetic force (p. 455)
Section Notes
• All magnets have two poles.
One pole will always point to
the north if allowed to rotate
freely, and it is called the
north pole. The other pole is
called the south pole.
• Like magnetic poles repel
each other; opposite magnetic
poles attract.
• All magnets are surrounded
by a magnetic field. The
shape of that magnetic field
can be shown with magnetic
field lines.
Visual Understanding
ELECTROMAGNETISM The two important
concepts in electromagnetism
were discovered by Oersted
and Faraday. Figure 13
on page 462 summarizes
Oersted’s
work, which showed
that an electric current
can produce
a magnetic field.
474
Skills Check
Chapter 18
SECTION 1 SECTION 2
• A material is magnetic if its
domains are aligned. Iron,
nickel, and cobalt atoms
group together in domains.
• Magnets can be classified as
ferromagnets, electromagnets,
temporary magnets,
and permanent magnets. A
magnet can belong to more
than one group.
• Earth acts as if it has a big
bar magnet in its core.
• Compass needles and the
north pole of magnets point
to Earth’s magnetic south
pole—which is close to
Earth’s geographic North
Pole.
• Auroras are most commonly
seen near Earth’s magnetic
poles because Earth’s magnetic
fields bend inward at
the poles.
Labs
Magnetic Mystery (p. 698)
Vocabulary
electromagnetism (p. 463)
solenoid (p. 463)
electromagnet (p. 464)
electric motor (p. 466)
Section Notes
• Oersted discovered that a
wire carrying an electric current
produces a magnetic
field.
• Electromagnetism is the
interaction between electricity
and magnetism.
• A solenoid is a coil of
current-carrying wire that
produces a magnetic field.
• An electromagnet is a solenoid
with an iron core. The
electromagnet has a stronger
magnetic field than a solenoid
of the same size does.
• Increasing the current in a
solenoid or an electromagnet
increases the magnetic field.
ELECTROMAGNETIC INDUCTION Faraday’s work
showed that a changing magnetic field can
induce an electric
current in a wire.
His results are
summarized in
Figure 21 on
page 469.
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