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CHAPTER
12
REVIEW
K/U
Knowledge/Understanding
Knowledge
For each question, select the best answer from the four
alternatives.
1. Which of these best describes the location of Earth’s
magnetic field? (12.1) K/U
(a) only inside Earth
(b) surrounding Earth
(c) outside Earth’s atmosphere
(d) both inside and surrounding Earth
2. The first compasses were most likely made of which
material? (12.1) K/U
(a) soft iron
(b) magnesium
(c) copper
(d) magnetite
3. Magnetic field lines
(a) sometimes cross each other
(b) point from south to north outside a magnet
(c) are farther apart where the magnet is stronger
(d) point from south to north inside a magnet
(12.1) K/U
4. Which best describes the force created when the
north poles of two magnets are brought together?
(12.1) K/U
(a) resonant
(b) negligible
(c) repulsive
(d) attractive
5. When using the electron flow model to illustrate
electrical current in a straight wire, what rule is used
to determine the direction of the resulting magnetic
field? (12.2) K/U
(a) right-hand rule for a straight conductor
(b) left-hand rule for a straight conductor
(c) conventional current method
(d) right-hand rule for solenoids
6. A version of the right-hand rule can be used to
determine which of the following? (12.2, 12.4,
12.5) K/U
(a) direction of the magnetic field created by a
current-carrying straight wire
(b) direction of the magnetic field created by a
current-carrying solenoid
(c) direction of the force on the current-carrying
conductor of an electric motor
(d) all of the above
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C
Communication
Thinking/Investigation
A
Application
Match each name on the left with the most appropriate
contribution on the right.
7. (a) Magnes of
Magnesia
(i) showed that a magnetic
field surrounds a currentcarrying wire
(b) Hans Christian (ii) created the first electric
Oersted
motor
(c) André-Marie
(iii) ancient Greek shepherd
Ampère
who discovered magnetite
(d) Michael
(iv) found that two wires with
Faraday
opposite currents created
a repulsive force (12.1,
12.2, 12.4, 12.5) K/U
Write a short answer to each question.
8. The attraction of two wires with current going in the
same direction tells us what about their magnetic
fields? (12.4) K/U
9. Solenoids are often used as controllable bar magnets.
Describe how the magnetic field lines of a bar magnet
and the magnetic field lines of a solenoid are similar
to each other. (12.4) K/U C
10. State the right-hand rule for a solenoid. (12.4) K/U
11. In Michael Faraday’s first electric motor, what
interacted with the magnetic field of the bar magnet
to cause the motion of the motor? (12.5) K/U
12. (a) According to the motor principle, what happens
to a current-carrying conductor as it cuts across
external magnetic field lines?
(b) What factors determine the magnitude of this effect
on the current-carrying conductor? (12.5) K/U
13. One of the first practical uses of the motor principle
was the development of analog meters. What is the
main advantage of an analog meter compared to a
modern digital meter? (12.5) K/U
14. (a) What did the invention of the split ring
commutator allow a DC motor to do?
(b) What other developments have improved the
design of DC motors? (12.6) K/U
Understanding
15. Earth has both a magnetic field and a gravitational
field. (12.1) K/U
(a) What is the difference between these two fields with
respect to the direction of the forces they cause?
(b) What is the difference between these two fields
with respect to the materials that they act upon?
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PRE-PUBLICATION DRAFT MATERIAL
16. (a) Draw the magnetic field lines created by two bar
24. Determine the direction of the current for the
magnets held close together with one north and
magnetic field shown in Figure 3. (12.2) T/I
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one south pole facing each other.
(b) Draw the magnetic field lines created by two bar
magnets held close together with their north
poles facing each other.
(c) How would your illustration from part (b) change
if the magnets were held with their south poles
facing each other? (12.1) K/U C
17. Describe how various magnets are used in the Maglev
train in Shanghai and in what direction the magnetic
Figure 3
forces are acting. (12.1) A C
25. What conclusion did Ampère draw from his experiments
18. Many physicists had hypothesized that electric
with two current-carrying wires? (12.4) K/U
currents produce magnetic fields, but Hans Christian
Oersted was able to confirm the hypothesis. (12.2) K/U
26. Two parallel wires are each carrying a current. There
(a) How did Oersted confirm that electric currents
is a magnetic force of attraction between the two
produce magnetic fields?
wires. (12.4) T/I C
(b) What further details did Oersted’s method of testing
(a) What do we know about the directions of the
his hypothesis provide about these magnetic fields?
currents, based on the magnetic force?
(b) What kind of magnetic force would be produced
19. What is the main similarity between the behaviour of
if both of the currents in the wires were reversed?
charged particles and that of magnetic poles? (12.2) K/U
(c) What kind of magnetic force would be produced
20. (a) How do the models of conventional current and
if only one current was changed?
electron flow differ from each other?
(d)
What
would the effect on the magnetic force be if
(b) How do conventional current and electron
the
currents
were increased?
flow affect how we determine the direction of a
K/U
(e) What would the effect on the magnetic force be if
magnetic field around
a straight
wire?
Ontario
Physics
11(12.2)
U
one current was increased and the other current
21. Using the page as a frame
of reference and applying
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was switched off?
the right-hand rule, determine
the following:
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FN
27. (a) Use your own words to describe a solenoid.
(a) What is the direction
produces
Crowle
Art Group
COof the current that
(b) Draw a current-carrying solenoid. Label the
a counterclockwise magnetic field on the page?
Deborah Crowle
direction of the current, the magnetic field lines,
(b) What is the direction of the magnetic field produced
1st T/Ipass
and the north and south poles of the solenoid.
by a current flowingPass
into the page? (12.2)
(12.4) K/U C
Approved
22. Determine the direction (clockwise or counterclockwise)
28. Explain how the right-hand rule for a solenoid
Not Approved
of the magnetic fields produced
by the currents in
helps us to understand the operation of a solenoid.
T/I
Figure 1. (12.2)
(12.4) K/U
(a)
(b) C12Q-F001a-OP11USB
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29. (a) Describe the effect of running a current through
a wire suspended between the north pole of one
magnet and the south pole of another magnet.
Figure 1
(b) What is the effect of reversing this current?
(c) Draw a diagram of the magnetic field lines of
23. Which direction on the compass will the needle point
both of these cases and the direction of the
for each scenario in Figure 2? (12.2) T/I
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resultant effects. (12.5) T/I C
30. (a) List the major components of a DC motor. State
whether each component is a stationary or a
conventional
conventional
N
rotating part.
N
current
current
W
E
W
E
(b) What is the name for the stationary parts of a DC
S
S
motor? What is the name for the rotating parts of
a DC motor? (12.6) T/I
31. (a) List three ways that the design of a DC motor can
(a)
(b)
be improved.
Figure 2
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PRE-PUBLICATION DRAFT MATERIAL
(b) If one of these three improvements is taken to an
extreme, it becomes undesirable. Which is it and
what is the risk that makes it less desirable than
the other two? (12.6) K/U
32. Using your own words, describe the problem of a split
ring commutator with a single split and describe the
solution that DC motor designers came up with to
overcome it. (12.6) K/U C
33. Explain the development of DC motors, beginning
with Oersted’s experiment and concluding with
modern DC motors. (12.2, 12.5, 12.6) K/U C A
34. Discuss the strengths and weaknesses of each of the
following medical imaging technologies: X-rays,
ultrasound, and magnetic resonance imaging.
(12.7) K/U A
Analysis and Application
35. In the images in Figure 4, there is a mistake in the
field lines. Copy each image and correct the mistake
(12.1) T/I
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return to pointing toward Earth’s magnetic north
pole. (12.2) K/U C
(a) What property of magnetic field lines does this
illustrate?
(b) How does the needle’s return to Earth’s magnetic
north pole illustrate this property of field lines?
39. Describe three ways an electromagnet can be more
advantageous than a permanent magnet, and provide
a useful example for each. (12.2) A C
40. (a) Name a household object that uses a magnet.
(b) Does this object use its magnet to interact with
another magnet or does it use its magnetic field
to produce a force on a metallic object?
(c) Is the magnet used in this object a permanent
magnet or an electromagnet?
(d) Draw a diagram of how this object’s magnet is
used. Be sure to include field lines. (Hint: You
may have to make an assumption about the
polarity of the magnet.) (12.4) K/U T/I C
41. There is a mistake in Figure 5. Copy the image and
correct the mistake. (12.4) T/I A
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N
N
direction of
conventional
current
S
S
(a)
(b)
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Figure 5
S
N
N
S
42. (a) A subwoofer uses a solenoid (voice coil) and a
permanent magnet to create vibrations of the
speaker cone. Describe the interaction between
the solenoid (voice coil) and the permanent
(c)
magnet.
Figure 4
(b) If the quality of the speaker is in part defined
by the strength of the solenoid, what properties
36. Describe why iron filings are useful for understanding
should the solenoid of a high-quality speaker
magnetic fields. (Hint: Look at many of the figures in
have? (12.4) K/U T/I C A
io Physics 11 U
Section 12.1.) (12.1) K/U C
43. Michael Faraday’s experiment that resulted in the first
04338
37. Using your own words, describe how the aurora
electric motor was based on the idea of movement
11USB
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borealis is an effect
of Earth’s
magnetic
field that is
Ontario
Physics
11
U
between a magnetic object and an external magnetic
up
observed
Crowle Art
Groupas a display of light. (12.1) K/U C A
field. What is the fundamental difference between his
0176504338
e
38. IfCrowle
a compass is moved away from a current-carrying
Deborah
motor and a compass, which is also a magnetic object
C12Q-F005-OP11USB
FN
conductor,
eventually
the
needle
of
the
compass
will
moving due to an external magnetic field? (12.5) C A
1st pass
Crowle Art Group
CO
ved
Deborah Crowle
38
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Pass
Approved
Not Approved
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44. Describe what is shown in Figure 6 and explain how
this simple diagram defines the fundamentals of the
motor principle. Be sure to discuss the interaction
between the magnetic field lines shown. (12.5) C A
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(b)
Figure 6
45. (a) Explain the right-hand rule for the motor
principle.
(b) Explain how you would orient your right hand
to determine the direction of the force produced
if the current moves toward the right and the
external magnetic field is pointing upward.
(c) Does the description in part (b) result in a force
into the page or out of the page? (12.5) T/I A
46. Galvanometers are used in circuits to measure
electrical signals. (12.5) K/U C A
(a) What two specific measurement devices contain a
galvanometer? What electrical property does each
ysics 11 U
measure?
(b) Explain for each measurement device how the
C12Q-F006-OP11USB galvanometer is included in the circuit.
Crowle Art Group
47. (a) Using your own words, explain the difference
Deborah Crowle
between a galvanometer and a DC motor.
1st pass
(b) What technology was used to make the transition
between a galvanometer and a DC motor, and
how does it work?
ed
(c) Draw and label a diagram of a simple DC motor.
Be sure to include both moving and stationary
components. (12.5, 12.6) C A
48. (a) Describe how a gasoline-electric hybrid car uses
an electric motor.
(b) Describe the primary benefit of using electric
motors in automobiles.
(c) What factors prevent a hybrid car from being
completely pollution free? (12.6) K/U A
describe how traditional brakes might be replaced
by magnetic brakes.
(b) Describe one benefit and one drawback of this
use of magnets over conventional parts.
(c) Describe how some other familiar technology
could benefit from the use of magnets. (Hint:
This can be anything from another form of
transportation to an object found in the home.)
50. This chapter discusses both natural magnetic
phenomena and technologies where magnetism
can be manipulated by humans. Compare natural
magnetic occurrences with any of the human-made
technologies discussed. List the differences and the
similarities. (12.1, 12.4, 12.6. 12.7) K/U C A
51. Compare two innovations that use electromagnetism.
Describe the ways electromagnetism is used to
produce the desired effect and the impact of the
technologies on daily life and society at large. (12.4,
12.6. 12.7) K/U A
Reflect on Your Learning
52. Describe several ways in which Oersted’s experiments
with electric current have shaped technology. A C
53. To understand the impact of electromagnetism
on our everyday lives, keep a journal of all your
interactions with DC motors for an entire day.
Remember that computer fans and hard drives, DVD
players, electric car windows, and vacuum cleaners,
among many other objects, all use DC motors to
make objects rotate. Make your list as complete as
possible. K/U C A
54. Pick an everyday item that uses electromagnetism.
Describe how your daily life would change without
that item. For example, without speakers, we would
have no cellphones. C A
Research
55. The Large Hadron Collider (LHC) is one of the
largest scientific undertakings in human history. It
relies heavily on electromagnets to control the path
and the speed of particles within the accelerator.
Choose one of the following topics and write a short
report about your findings: the use of electromagnets
within the LHC, the research goals of the particle
accelerator, the recent results of testing at the LHC.
T/I
Evaluation
49. Maglev trains use magnets to reduce friction and to
produce forward motion. This is a replacement for
wheels and steam engines. (12.1) K/U A
(a) Describe a possible use of magnets to replace
a component of the automobile. For example,
C
A
56. The aurora borealis and aurora australis (the northern
and southern lights) have been topics of discussion
in both mythology and science. Research an ancient
mythological explanation for the northern lights.
Write a paragraph that explains this mythological
explanation and a paragraph about the current
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scientific understanding of the aurora. Compare the
two. T/I C A
57. Nikola Tesla dreamed of transmitting electrical
energy without using electricity grids. Research some
of the potential applications of wireless electricity
today and the consequences that these applications
could have on everyday life. T/I C A
58. Solenoids are used in subwoofers, electric bells, and
cars, among other applications. Research other uses
for solenoids. Write a short report that includes a
discussion of the application and a diagram of how
the solenoid is employed. T/I C A
59. Many companies are developing and producing
electric vehicles. Research one company. T/I C A
(a) Write a brief history of the company.
(b) Does the company boast any specific
technological advances over its competitors? If
yes, what is it? If no, how does the company plan
to gain a competitive edge?
(c) Write a paragraph or two describing any of the
company’s major successes or failures.
(d) What is your impression of the vehicles produced
by this company? Be sure to back up your
arguments with reasoning.
40 Chapter 12 • Electromagnetism
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