Magnetism Review
Physics 2012
Name____________
1. 0 At a location near the equator, the earth's magnetic field is horizontal and points north.
An electron is moving vertically upward from the ground. What is the direction of the
magnetic force that acts on the electron?
A. North
B. East
C. South
D. West
E. The magnetic force is zero.
2.0 The drawing shows four situations in which a positively charged particle is moving with a
velocity v through a magnetic field B. In each case, the magnetic field is directed out of the
screen toward you, and the velocity is directed to the right. In only one of these drawings is
the magnetic force F physically reasonable. Which one is it?
A.
B.
C.
D.
3.0 Suppose you want to produce a strong magnetic field that is constant in magnitude and
direction in a region of space. Which one of the following would you choose to produce this
field?
A. The interior region of a long current-carrying solenoid.
B. The exterior region of a long current-carrying solenoid.
C. The region surrounding a long, straight, current-carrying wire.
D. The region surrounding a loop of a current-carrying wire.
4.0 Which one or more of the following choices is (are) true regarding how a magnetic field
acts on a charged particle. A magnetic field __________
1.
2.
3.
4.
can increase the speed of a moving particle.
can cause a moving particle to accelerate.
always exerts a force on a moving particle.
can exert a force on a stationary particle.
A. 2 and 3
B. 1 and 2
C. 2
D. 3
E. 2 and 4
5.
Which one of the following statements concerning the magnetic force on a
charged particle in a magnetic field is true?
A)
It is a maximum if the particle is stationary.
B)
It is zero if the particle moves perpendicular to the field.
C)
It is a maximum if the particle moves parallel to the field.
D)
It acts in the direction of motion for a positively charged particle.
E)
It depends on the component of the particle's velocity that is
perpendicular to the field.
6.
Two electrons are located in a region of space where the magnetic field is
zero. Electron A is at rest; and electron B is moving westward with a constant
velocity. A non-zero magnetic field directed eastward is then applied to the region.
In what direction, if any, will each electron be moving after the field is applied?
A)
B)
C)
D)
E)
electron A
at rest
northward
at rest
southward
upward, away from earth
electron B
westward
eastward
eastward
downward, toward the earth
westward
7.
Two particles move through a uniform magnetic field that is directed out of the
plane of the page. The figure shows the paths taken by the two particles as they move
through the field. The particles are not subject to any other forces or fields. Which one of
the following statements concerning these particles is true?
( Remember the RHR gives the force on a positive charge, the force on a negative charge
is opposite)
A.
B.
C.
D.
E.
The particles may both be neutral.
Particle 1 is positively charged; 2 is negative.
Particle 1 is positively charged; 2 is positive.
Particle 1 is negatively charged; 2 is negative.
Particle 1 is negatively charged; 2 is positive.
8.
A solenoid of length 0.25 m and radius 0.02 m is comprised of 120 turns of
wire. Determine the magnitude of the magnetic field at the center of the solenoid
when it carries a current of 15 A.
A)
2.26 x 10-3 T
B)
4.52 x 10-3 T
C)
9.05 x 10-3 T
D)
7.50 x 10-3 T
E)
zero tesla
9.
An overhead electric power line carries a maximum current of 125 A. What is
the magnitude of the maximum magnetic field at a point 4.50 m directly below the
power line?
A)
5.56 x 10-6 T
B)
1.75 x 10-5 T
C)
3.49 x 10-5 T
D)
4.69 x 10-4 T
E)
7.95 x 10-3 T
10.
A charged particle is moving in a uniform, constant magnetic field. Which one
of the following statements concerning the magnetic force exerted on the particle is
false?
A)
It does no work on the particle.
B)
It increases the speed of the particle.
C)
It changes the velocity of the particle.
D)
It can act only on a particle in motion.
E)
It does not change the kinetic energy of the particle.
11.
Two loops carry equal currents I in the same direction. The loops are held in the
positions shown in the figure and are then released. Which one of the following
statements correctly describes the subsequent behavior of the loops?
A.
B.
C.
D.
E.
Both loops move to the left.
The loops remain in the positions shown.
The top loop moves to the right; the bottom loop moves to the right.
The loops repel each other.
The loops attract each other.
12. A wire is bent into the shape a circle of radius r = 0.1 m and carries a 20-A
current in the direction shown.
What is the direction of the magnetic field at the center of the loop?
A.
B.
C.
D.
E.
to the right of the page
to the left of the page
toward the top of the page
into the plane of the paper
out of the plane of the paper
Answers:
1. B
2. A
3. A
4. C
5. E
6. A
7. D
8. C
9. A
10. B
11. E
12. D