MAGNETISM CAN PRODUCE CURRENT.
SECTION
21.3 Reading Study Guide A
BIG IDEA Current
KEY CONCEPT
can produce magnetism, and magnetism can produce current.
Magnetism can produce current.
Vocabulary
generator a device that changes energy of motion, or kinetic energy,
into electrical energy
direct current an electrical charge that flows in only one direction
alternating current an electrical charge that changes direction at regular periods
transformer a device that increases or decreases voltage
Review
1.
What happens when electric current moves through a wire?
Take Notes
Magnets are used to generate electric current.
CHAPTER 21
Magnetism
2.
What happens when a magnet is moved inside a coiled wire that is
in a circuit?
A. Generating an Electric Current
3.
Complete the graphic organizer to show how a cell phone charger uses a
generator to produce electric current.
A. Generator
handle
is turned.
F. The battery is
____________.
B. A series of
____________ turn.
E. Electric
current is
generated.
158 ELECTRICITY AND MAGNETISM, CHAPTER 21, READING STUDY GUIDE A
C. Shaft of the
generator
turns.
D. Coils of wire
____________.
Copyright © by McDougal Littell, a division of Houghton Mifflin Company
I.
B. Direct and Alternating Currents
Compare a direct current with an alternating current by writing Yes or No on the
lines below.
Alternating Current
4.
Charge flows in a closed path.
____________________
____________________
5.
Charge flows in one direction.
____________________
____________________
6.
Current is produced by a generator.
____________________
____________________
7.
Current changes direction at regular
intervals.
____________________
____________________
8.
Why is the generator of a car called an alternator?
9.
Draw a picture to show two parts of a car that use electrical energy.
CHAPTER 21
Magnetism
Copyright © by McDougal Littell, a division of Houghton Mifflin Company
Direct Current
II. Magnets are used to control voltage.
10.
A transformer
• increases or decreases ____________
• uses ____________ to control voltage
• has two coils around an ____________
What is the purpose of a transformer?
ELECTRICITY AND MAGNETISM, CHAPTER 21, READING STUDY GUIDE A 159