Students Offering Support
University of Windsor Chapter
Physics 141
Take Home Practice Problems
Preparation made by:
Lucas Foster, Julia Petta, Nathan Doupnik and Jake Frank
Treat this as you would an actual exam. Closed book, no cheat sheet, and show all your work. This format will
resemble that of a physics midterm.
1. The units of a magnetic field are:
a. N/C*m
b. T
c. Kg/C*s
d. Two of the above
2. In the formula 𝐹=qv x B
a. All three vectors must be mutually perpendicular
b. F must be perpendicular to B but not v
c. F must be perpendicular to v but not B
d. F must be perpendicular to both v and B
3. A proton moves in the negative x direction, through a uniform magnetic field in the
negative y direction. The magnetic force on the proton must be:
a. In the negative z direction
b. In the positive z direction
c. In the positive x direction
d. In the positive y direction
4. Choose the correct statement:
a. The magnetic force on a charged particle is never in the direction of its velocity
b. The magnetic force on a charged particle is in the direction of its velocity if it’s
moving in the opposite direction of the field
c. The magnetic force on a charged particle is in the direction of its velocity if it’s
moving in the direction of the field
d. The magnetic force on a charged particle is in the direction of its velocity if it’s
moving perpendicular to the field
5. An electron is moving south and the magnetic field exerted on the electron is north.
What must the magnetic force be?
a. up
b. down
c. zero
d. one
6. If a uniform magnetic field is directed to the West and a wire is carrying a current out of
the page. The magnetic force on the wire must be:
a. Toward the West
b. Toward the North
c. Toward the East
d. Toward the South
7. You are looking down at a wire that is carrying a current that is travelling to the east.
What is the direction of the magnetic field between you and the wire?
a. North
b. East
c. South
d. West
8. Solenoid 2 has three times the radius of solenoid 1. What is the ratio of the magnetic
field in the interior of solenoid 2 compared to that in the interior of 1?
a. 6
b. 4
c. 2
d. 1
9. The magnetic field a distance of 4cm from a long straight current-carrying wire is 2.0 x
10-6 T. What is the current in the wire?
a. 1.0A
b. 0.4A
c. 0.8A
d. 0.5A
10. Two long straight parallel wires carry currents in the same direction. The currents are
6.0 A and 5.0A and the wires are separated by 0.30cm. The magnetic field in Tesla at a
point midway between the wires is:
a. 0
b. 1. 5 x 10-4
c. 1.3 x 10-4
d. 2.0 x 10-3
11. Two parallel wires, 6cm apart, carry currents 2 A and 4A respectively in opposite
directions. What is the force per unit length in N/m of one wire on the other?
a. 3 x 10-5, repulsive
b. 3 x 10-5, attractive
c. 1.5 x 10-5, repulsive
d. 1.5 x 10-5, attractive
12. The diagram shows three different circular loop arrangements that are centered on
vertical axes and carrying identical currents in the directions indicated. Rank the
arrangements according to the magnitudes of the magnetic fields as the midpoint
between the loops on the central axis.
a. 1,2,3
b. 3,2,1
c. 2,1,3
d. 2,3,1
13. A uniform magnetic field makes an angle of 30’ with the z-axis. If the magnetic flux
through a 2m2 portion of the xy plane is 5Wb then the magnetic flux through a 4m2
portion of the same plane is:
a. 10Wb
b. 5Wb
c. 2Wb
d. 1Wb
14. The units of motional emf are:
a. tesla/second
b. tesla x meter/ second
c. volt/second
d. volt
15. A long straight wire is in the plane of a rectangular conducting loop. The straight wire
carries a constant current i. If the magnetic field begins to increase, the induced current
in the rectangle will be:
a. Clockwise
b. Counterclockwise
c. Zero
d. None of the above
16. A long straight wire is in the plane of a rectangular conducting loop. The straight wire
initially carries a constant current i. While the current i is being shut off (decreasing), the
induced current will be:
a. Clockwise
b. Counterclockwise
c. Zero
d. None of the above
17. A rectangular loop of wire is placed midway between two long straight parallel
conductors as shown. The conductors carry currents i1 and i2, as indicated. If i1 is
increasing and i2 is constant, then the induced current in the loop is:
a. Clockwise
b. Counterclockwise
c. Zero
d. None of the above
18. In order of increasing wavelength; which of the following is correct?
a. Radio waves, infrared light, x-rays, ultraviolet light, visible light
b. X-rays, ultraviolet light, visible light, radio waves, infrared light,
c. X-rays, ultraviolet light, visible light, infrared light, radio waves
d. Radio waves, ultraviolet light, infrared light, visible light, x-rays
19. The law of reflection states:
a. The angle of incidence equals the angle of reflection
b. The angle of incidence does NOT equal the angle of reflection
c. The incident, reflected, and refracted rays are lie in the same plane
d. A and C
20. The diagram shows the passage of a ray of light from air into a substance X. The index of
refraction of X is:
a. 0.5
b. 1.0
c. 1.5
d. 2.0
21. An object attached to one end of a spring makes 20 vibrations in 10 seconds. Its frequency
is:
a) 2Hz
b) 10s
c) 0.05Hz
d) 2s
e) 0.50s
22. When a body executes simple harmonic motion, its acceleration at the ends of its path must
be:
a) zero
b) less than g
c) more than g
d) suddenly changing in sign
e) none of these
23. The position x of an object varies with time t. For which of the following equations relating x
and t is the motion of the object simple harmonic motion? (There may be more than one
correct choice.)
a) x = 5 sin23t
b) x = 8 cos 3t
c) x = 4 tan 2t
d) x = 5 sin 3t
e) x = 2 cos(3t - 1)
24. A mass M is attached to an ideal massless spring. When this system is set in motion with
amplitude A, it has a period T. What is the period if the amplitude of the motion is increased to
2A?
a) 2T
b) T/2
c) √2T
d) 4T
e) T
25. A certain frictionless simple pendulum having a length L and mass M swings with period T. If
both L and M are doubled, what is the new period?
a) 4T
b) 2T
c) √2T
d) T
e) T/4
26. Four traveling waves are described by the following equations, where all quantities are
measured in SI units and y represents the displacement.
I: y = 0.12 cos(3x - 21t)
II: y = 0.15 sin(6x + 42t)
III: y = 0.13 cos(6x + 21t)
IV: y = -0.27 sin(3x - 42t)
Which of these waves have the same period?
a) I and III, and also II and IV
b) I and IV, and also II and III
c) I and II, and also III and IV
d) All of them have the same period.
e) They all have different periods.