This exam consists of 28 questions; true-false
questions are worth 2 points each, three-choice multiple choice
questions are worth 3 points each, five-choice multiple choice questions
are worth 6 points each. The maximum possible score is 118. When the
exam was given, the mean was 91.0; the median was 93. Click here to
page2 of the formula sheet that came with
A long straight wire carries a current of 30 A as shown in the
figure. A proton (q = 1.6 × 10-19 C) is moving with
velocity 2 × 108 m/s. The velocity makes an angle of
20° with the direction of the wire. At the instant considered in
this problem, the proton is 0.25 m away from the wire.
What is the magnitude of the magnetic field due to the wire at the
position of the proton?
(a) 1.9 × 10-7 T
(b) 8.2 × 10-6 T
(c) 5.3 × 10-6 T
(d) 2.4 × 10-5 T
(e) 2.6 × 10-4 T
(a) 7.7 × 10-16 N
(b) 9.5 × 10-16 N
(c) 3.7 × 10-15 N
(d) 4.9 × 10-15 N
(e) 6.2 × 10-14 N
(a) The force is in the plane of the paper.
(b) The force is perpendicular to the plane of the paper.
A plastic cube measuring 1 m on each side is placed in a uniform
magnetic field of magnitude 1 T which points in the vertical direction,
as in the diagram below.
A charged particle enters the cube at point a
and exits at point b, leaving a track (dashed line) which is a quarter
of a circle. Note that the plastic cube does not interfere with the
motion of the charged particle and has permeability μ0
(treat the cube as vacuum for the purposes of this problem). The
magnitude of the charge is 1.6 × 10-19 C and its velocity is
4.8 × 107 m/s.
What is the mass of the charged particle?
(a) 2.49 × 10-28 kg
(b) 1.62 × 10-25 kg
(c) 1.67 × 10-27 kg
(d) 9.08 × 10-31 kg
(e) 1.88 × 10-28 kg
Two identical solenoids are arranged as shown in the figure above.
The current in each solenoid is the same. The two solenoids are now
joined to make one solenoid, as shown in the figure below. The current
in this solenoid is the same as the current in each of the original
The magnetic field in this solenoid, compared with the magnetic field
in each of the original solenoids, is
(a) half as big.
(b) twice as big.
(c) the same.
(a) reverse direction.
(b) stay the same.
A rectangular loop of wire has sides with lengths 1.5 m and 2.0 m as
shown in the figure below. The loop has one turn of wire and carries a
current of 13 A in the direction shown on the cd side. In the
same plane as the loop is a uniform magnetic field of magnitude 4.6 mT.
The field makes an angle of 37° with the bd (and ac)
sides of the loop, as in the figure.
What is the magnitude of the magnetic force on the cd side of
(a) 4.3 × 10-3 N
(b) 6.7 × 10-2 N
(c) 9.6 × 10-2 N
(d) 1.3 × 10-1 N
(e) 2.6 × 10-1 N
(a) out of the page.
(b) into the page.
(a) 7.2 × 10-3 Nm
(b) 1.1 × 10-2 Nm
(c) 2.9 × 10-2 Nm
(d) 4.6 × 10-2 Nm
(e) 1.8 × 10-1 Nm
A constant magnetic field is pointing into the page within the region
indicated by "x" marks in the figure below.
Three identical rectangular loops of conducting wire are lying flat on
the page and are moving to the right with the same constant velocity.
The resistance is the same for each loop.
Which one of the following statements is true about the induced emf
ε in the loops?
(a) εB > εA > εC
(b) εA > εC > εB
(c) εC > εA > εB
(a) flows clockwise.
(b) flows counterclockwise.
(c) is zero.
What is the magnitude of the emf in the circuit composed of the two
moving conductors and the part of the rails between the two conductors?
(a) 20.9 mV
(b) 13.2 mV
(c) 7.7 mV
(d) 5.5 mV
(e) 0.0 mV
What is the peak electric field of the laser beam at the atom?
(a) 1230 V/m
(b) 1.23 × 109 V/m
(c) 1.32 V/m
(d) 7.42 × 105 V/m
(e) 8.68 × 105 V/m
Two polarizers are arranged as in the diagram above. In between the
polarizers is a perfectly transparent crystal that rotates the
polarization of light that passes through it by 45° in the direction
indicated on the diagram by the large filled arrow. Unpolarized light
with intensity I0 is sent from point A in the positive z
direction (toward point C).
What is the intensity at point B?
(b) I0 / 3
(c) I0 / 2
(b) I0 / 2
(c) I0 / √2
(c) I0 / √2
An antenna is connected to a tunable capacitor with capacitance C and
a resistor in order to make the circuit in the diagram. The fixed
capacitor, inductor, and resistor have values 0.03 μF, 1 μH, and
What capacitance C should an engineer tune the capacitor to in order
to make the circuit resonant with a broadcast at 580 kHz (local station
(a) 4.5 × 10-8 F
(b) 1.5 × 10-9 F
(c) 7.3 × 10-8 F
(d) 1.7 × 10-8 F
(e) 1.2 × 10-8 F
(a) 25 Ω
(b) 50 Ω
(c) 100 Ω
(d) 10 Ω
(e) 12 Ω
(a) 1.10 m
(b) 517 m
(c) 0.350 m
(d) 605 m
(e) 1050 m
A mechanical crank is used to turn a rectangular loop with area 0.5
m2 at angular frequency Ω in the presence of a magnetic
field B = 2 T as shown above. The 30 V peak EMF produced
in the loop results in a peak voltage across the primary of the
transformer of Vp = 30 V. The secondary windings are
connected to a 10 Ω resistor. The secondary coil has three times
as many windings as the primary coil.
What is the peak voltage across the secondary of the
(a) Vs = 30 V
(b) Vs = 90 V
(c) Vs = 10 V
(a) 565 W
(b) 103 W
(c) 405 W
(d) 210 W
(e) 698 W
A series RLC circuit is connected to a generator that operates at a
frequency of 1 Hz. This circuit is used to run a pacemaker, which is
connected in parallel to the inductor (the pacemaker has a very high
resistance and does not change the operation of the circuit). The
resistor, capacitor, and inductor have values R = 10 Ω, C = 1 mF,
and L = 20 H.
What is the rms current in the circuit when the rms voltage across
the inductor is 1 kV?
(a) 7.96 A
(b) 1.23 A
(c) 10.3 A
(d) 1.05 A
(e) 6.54 A
(a) 305 V
(b) 278 V
(c) 126 V
(d) 558 V
(e) 1.00 V