Name
Date
Magnetism and Its Uses
Section 3 Producing Electric Currents
Scan the headings, figures, and captions in Section 3 of your book.
Write three questions that come to mind.
1. Accept all reasonable responses.
2.
3.
Review
Vocabulary Define voltage difference to show its scientific meaning.
voltage difference
related to the force that causes electric charges to flow;
measured in volts (V)
New
Vocabulary Use your book to define the following key terms.
generator
generation of a current by a changing magnetic field
device that transforms mechanical energy into electrical energy
by electromagnetic induction
turbine
large wheel that rotates when pushed by steam, wind, or water;
often connected to a magnet for generating electricity
direct current (DC)
electric current that flows in only one direction
alternating current
(AC)
electric current whose direction is reversed in a regular pattern
transformer
device that increases or decreases the voltage of an alternating
current
Academic
Vocabulary Use a dictionary to define regulate as it might be used in science.
regulate
86
Magnetism and Its Uses
to fix or adjust the time, amount, degree, or rate of
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
electromagnetic
induction
Name
Date
Section 3 Producing Electric Currents
Electromagnetic
Induction
(continued)
Organize the process of creating electrical energy from mechanical
energy. Complete the concept map.
I found this information
on page
.
SE, pp. 217–218
RE, pp. 119–120
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Provide this word
bank for extra help if
needed:
Coal
Current in wire coils
Natural gas
Nuclear reactor
Oil
Rotating magnets
Thermal
Turbines
Water
Wind
Wind
Water
Power source
Nuclear reactor
Thermal
Fossil fuels
Turbines
Natural gas
process of
electromagnetic
induction
Generator
Coal
Oil
Rotating magnets
Current in wire coils
Induce
electrical energy you use
Direct and
Alternating
Currents
I found this information
on page
.
SE, p. 220
RE, p. 121
Predict three electrical devices in your home that will stop working
in a power failure, and which devices will continue to work.
Describe the two types of current used by these devices.
Works
Doesn’t Work
Devices
Accept all reasonable
responses of batterypowered devices.
Accept all reasonable
responses of devices
that plug into wall
outlets.
Description
of Current
Direct current (DC)—
current flows in one
direction.
Alternating current
(AC)—current reverses
direction twice during
each rotation of coil in
the generator.
Magnetism and Its Uses
87
Name
Date
Section 3 Producing Electric Currents
Transformers
I found this information
on page
.
(continued)
Compare the two types of transformers using a Venn diagram. List
at least two pieces of information in each category.
Accept all reasonable responses.
SE, p. 220
RE, p. 122
Step-up
Transformer
Step-down
Transformer
Both
Have primary coil
and secondary coil.
Coils wrapped
around same iron
core.
Input voltage passes
through primary coil.
Changing current in
primary coil causes
output voltage in
secondary coil.
Decreases
voltage
Secondary coil
has fewer turns
than primary coil.
Transmitting
Electrical Energy
Analyze why a transformer is needed to provide power to your
home with the correct voltage.
I found this information
on page
.
Accept all reasonable answers. Power lines carry electrical
SE, p. 222
RE, pp. 121–122
energy at a high voltage in order to reduce heat created by the
electrical resistance of long wires. The transformer decreases the
voltage to a level that the electrical appliances can use.
S YNTHESIZE I T
Evaluate how the current produced from a hand-crank
generator would change as the handle is rotated forward and then backward.
Accept all reasonable responses. When the handle is turned in one direction, the current
flows in one direction. When the handle stops turning, the current stops flowing. When
the handle is rotated in the opposite direction, the current flows in the opposite direction.
Either direction will light a light bulb, however.
88
Magnetism and Its Uses
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Increases
voltage
Secondary
coil has
more turns
than primary
coil.
Name
Date
Tie It Together
Magnetism and Its Uses
Plan an expedition to find Earth’s south magnetic pole. Plan an experiment to see how near
the south magnetic pole is to the geographic north pole. Don’t forget that you will require
power on your trip to run various communication and scientific equipment.
Accept all reasonable responses.
Equipment list:
compasses, maps globes, boats, generators, or batteries
State your hypothesis.
Students will probably hypothesize that the magnetic pole is 1500 km from the
geographic pole.
Describe your experiment.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Use compasses in various parts of the north to locate the position of the magnetic
pole. Power for instruments can be provided by generator or batteries.
Analyze and interpret your predicted data.
The position of the magnetic pole can be superimposed on a map of the
geographic pole.
Draw a top view of Earth from your hypothesis and proposed data. Include some
meridians and the positions of both poles.
Magnetism and Its Uses
89
Name
Date
Magnetism and Its Uses
Chapter Wrap-Up
Now that you have read the chapter, think about what you have learned and complete
the table below.
1. Write an A if you agree with the statement.
2. Write a D if you disagree with the statement.
After You
Read
Magnetism and Its Uses
• A magnetic field is weakest close to the
magnet.
D
SE p. 203
RE p. 108
• The north pole of a compass always
points to Earth’s south magnetic pole.
A
SE p. 205
RE p. 110
• Moving charges can create magnetic
fields.
A
SE p. 209
RE p. 113
• Windmills change chemical energy into
electrical energy.
D
SE p. 218
RE p. 121
Compare your previous answers to these.
Review
Review the information you included in your Foldable.
Study your Science Notebook on this chapter.
Study the definitions of vocabulary words.
Review daily homework assignments.
Re-read the chapter and review the charts, graphs, and illustrations.
Review the Self Check at the end of each section.
Look over the Chapter Review at the end of the chapter.
S UMMARIZE I T
After reading this chapter, list at least five ways magnets
are used. Accept all reasonable responses.
Magnets are frequently used in compasses, electromagnets, solenoids, galvanometers,
turbines, and in producing electricity. Some students may know of magnetic applications
in medicine.
90
Magnetism and Its Uses
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Use this checklist to help you study.