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 87;
the mean score was 65.9; the median was 69.
The exam period was 75 minutes. Click here to see page1
page3 of the formula sheet that came
with the exam.
Some helpful information: • A reminder about prefixes: p
(pico) = 10-12; n (nano) = 10-9; μ (micro) =
10-6; m (milli) = 10-3; k (kilo) =
10+3; M or Meg (mega) = 10+6; G or Gig (giga) =
The diagram, not necessarily drawn to scale, shows two chambers, the
first with a magnetic field whose absolute value B1 =
0.028 T and the second with a magnetic field of absolute value
B2 = 0.092 T. These fields are perpendicular to the
A particle with a mass m = 4.4 × 10-27 kg
enters the first chamber in its lower left corner, moving with an
initial speed v = 105 m/s directed upward (in the
positive y-direction). It is moving due rightward (in the
positive x-direction) as it passes into the second chamber, and
moving straight upward as it exits the second chamber.
What is true regarding W1, the work done on the
charge by the magnetic field in the first chamber?
(a) W1 < 0
(b) W1 = 0
(c) W1 > 0
(a) 9.8 × 10-20 C
(b) 2.0 × 10-19 C
(c) 3.2 × 10-19 C
(a) into the page
(b) out of the page
(a) 6.4 cm
(b) 9.8 cm
(c) 21 cm
The diagram shows two wires perpendicular to the page. At x =
- 6 cm on the x-axis, a wire carries a current
I1 = 2.2 A into the page; at x = 6 cm on the
x-axis, a wire carries a current I2 = 2.2 A out
of the page. The questions below will refer to a point A at
y = 16 cm on the y-axis, and a point B at x
= 10 cm on the x-axis.
What is the direction of the magnetic field at point A?
(a) to the right (positive x-direction)
(b) to the left (negative x-direction)
(c) upward along the page (positive y-direction)
(d) downward along the page (negative y-direction)
(e) perpendicular to the page
(a) into the page
(b) out of the page
(c) neither of the above; the force vector lies in the plane of the page
(a) 4.4 × 10-7 N
(b) 8.4 × 10-7 N
(c) 1.9 × 10-6 N
(d) 3.7 × 10-6 N
(e) 8.0 × 10-6 N
A transformer 840 turns of wire in its primary and 660 turns of wire
in its secondary. A voltage Vrms = 120 volts is
applied to the primary. A current Irms = 0.16 A flows
into the primary. A light bulb -- acting like an ideal resistor -- is
attached to the secondary.
What is the resistance of the light bulb?
(a) 460 Ω
(b) 90 Ω
(c) 750 Ω
(d) 950 Ω
(a) Yes, sometimes the bulb has to go dark.
(b) No, there is no reason that the bulb ever has to go dark.
(a) The magnet slows the coin as it enters the field and speeds it back up as it leaves.
(b) The magnet slows the coin as it enters and slows the coin as it leaves.
(c) The magnet has no noticeable effect on copper.
A bar is free to slide along a pair of metal tracks separated by a
distance of L = 19 cm. (You may ignore friction between the bar
and the tracks.) At one end, the tracks are connected electrically by a
resistor R = 0.27 Ω. You should assume the metal bar
completes an electric circuit. An unknown magnetic field
B points out of the page. The bar moves at 3.4 m/s,
resulting in an electromotive force of 0.055 volts across the resistor.
What magnetic force acts on the sliding bar?
(a) 3.3 × 10-3 N
(b) 0.87 N
(c) 0.17 N
(a) 0.023 T
(b) 0.046 T
(c) 0.085 T
(a) clockwise (left to right through the resistor)
(b) counter-clockwise (right to left through the resistor)
True or False:
at the instant shown, the voltage across the capacitor is decreasing
(becoming more negative).
The diagram shows a single loop of wire spinning in the presence of a
magnetic field B = 0.6 T. The width w = 18 cm, the length
L = 15 cm, and the loop is rotating at 26 revolutions per second.
You should assume that the loop has a total resistance of 6.8 Ω.
At the instant shown, the segment marked "L" is moving toward the
back of the page. (It will soon be behind the vertical dashed axis
around which the loop is rotating.) At this instant shown, which way is
the induced current in that segment flowing?
(a) It is flowing upward in the segment marked "L".
(b) It is flowing downward in the segment marked "L".
(c) At the instant shown, no current flows in the segment marked "L".
(a) 0 Nm
(b) 1.0 × 10-3 Nm
(c) 6.3 × 10-3 Nm
(d) 0.23 Nm
(e) 0.39 Nm
In the RLC circuit shown, R = 140 Ω,
XL = 30 Ω and XC = 110
Ω. A function generator applies an alternating voltage of
frequency f = 240 Hz and peak voltage Vmax = 11
What rms current Irms is delivered to the above
(a) 0.042 A
(b) 0.048 A
(c) 0.059 A
(d) 0.068 A
(e) 0.084 A
(a) These peaks occur at the same time.
(b) These peaks are separated by one half cycle.
(c) Neither of the above is true for this circuit.
(a) 0.33 W
(b) 0.38 W
(c) 0.43 W
(a) 240 Hz
(b) 460 Hz
(c) 600 Hz
(d) 880 Hz
(e) 1200 Hz
A solenoid connected to a battery produces a magnetic field of 0.004
T. The solenoid has 300 turns of wire along an axis of length 10 cm and
diameter of 3 cm. The picture shows a typical solenoid, before the
battery has been attached.
How much current must flow for this coil to produce the required
(a) 0.01 A
(b) 0.1 A
(c) 1 A
(a) 1.4 × 10-4 V
(b) 5.6 × 10-3 V
(c) 7.1 × 10-3 V
(a) The inductance of both will be the same.
(b) The new solenoid has twice the inductance of the original one.
(c) The new solenoid has four times the inductance of the original one.