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 143.
The exam period was 90 minutes; the mean score was 109.9; the median was
114. 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) = 10+9.
Two positively charged particles enter a region of uniform
magnetic field B. The B field is oriented perpendicular to the page.
The paths of the two charged particles are shown.
Which direction is the B field pointing?
(a) into the page
(b) out of the page
(a) particle a
(b) particle b
(a) L = 0.33 m
(b) L = 0.50 m
(c) L = 1.50 m
(d) L = 2.67 m
(e) L = 7.50 m
(a) magnet A
(b) magnet B
(c) They hit at the same time.
(a) 2.75 Hz
(b) 4.42 Hz
(c) 8.84 Hz
(d) 30.31 Hz
(e) 55.56 Hz
A circular loop (radius r = 0.25 m) is sitting (not moving) in a
spatially-uniform magnetic field (as shown below). The loop has a
resistance per unit length of 5 Ω/m. The strength of the field is
B(t)= (1.5 +(0.2)t)
where B is in tesla and t is in seconds.
What is the flux Φ through the loop at time t = 0 s?
(a) 0 T-m2
(b) 0.03 T-m2
(c) 0.26 T-m2
(d) 0.75 T-m2
(e) 1.31 T-m2
(a) 0 T-m2
(b) 0.46 T-m2
(c) 1.20 T-m2
(d) 2.73 T-m2
(e) 5.10 T-m2
(a) 4.3 mA
(b) 2.5 mA
(c) 7.0 mA
(d) 10.3 mA
(e) 25.0 mA
(a) a1 / a2 = ¼
(b) a1 / a2 = ½
(c) a1 / a2 = 1
(d) a1 / a2 = 2
(e) a1 / a2 = 4
Which of the following would decrease the magnetic flux through
the coil? (Allow the circuit to reach new steady conditions
(a) increasing battery voltage
(b) increasing the resistance
(c) increasing the number of loops around the tube
A conducting bar slides along metal rails 6 meters apart at a
constant speed of v = 3 m/s. A resistor with resistance R = 100 Ω
is connected across the rails. The bar and rails are in a magnetic
field of magnitude B = 2.5 × 10-4 T, pointing out of
In which direction does the induced current flow through the resistor
R in the above picture?
(a) 2.0 × 10-7 W
(b) 4.0 × 10-7 W
(c) 4.5 × 10-5 W
(d) 2.0 × 10-3 W
(e) 4.0 × 10-3 W
(a) increases by a factor of 4
(b) increases by a factor of 2
(c) remains the same
(d) decreases by a factor of ½
(e) decreases by a factor of ¼
A charged particle is traveling at speed v. It encounters a static
magnetic field oriented perpendicular to its path. The particle changes
(a) speed ( = magnitude of the velocity).
(c) both its speed and direction.
(d) neither its speed or direction.
(e) All of the above scenarios are possible.
The diagram below shows a generator consisting of a square loop of 5
coils of area 0.1 m2 in a magnetic field of 0.05 T. The loop
is rotating at an angular frequency ω = 20 rad/s.
What is the maximum induced emf, Vmax?
(a) 0.1 V
(b) 5 V
(c) 0.5 V
(d) 1 V
(e) 1.5 V
(a) Vmax2 / R
(b) Vmax2 / (√2R)
(c) Vmax2 / (2R)
(d) Vmax R
(e) Vmax R2
(a) 7.5 H
(b) 15 H
(c) 30 H
(d) 100 H
(e) 225 H
A particle is placed in a uniform magnetic field of strength 1 T. The
particle has a velocity of 400 m/s, perpendicular to the magnetic field.
If the particle moves in a circle of radius 4 m, what is its ratio of
charge to mass (q/m), in Coulombs per kg?
(a) q/m = 0 C/kg
(b) q/m = 25 C/kg
(c) q/m = 50 C/kg
(d) q/m = 100 C/kg
(e) q/m = 200 C/kg
(a) 200 V
(b) 400 V
(c) 800 V
(d) 1200 V
(e) 1600 V
Given are two long wires carrying currents. The first is located at
(x = 0, y = 1 m) and carries a current of 2 A directed out of the page.
The second is located at (x = 0, y = -1 m) and carries a current of 1 A
directed into the page. (See the figure.)
What is the magnitude of the magnetic field at the origin?
(a) 1 × 10-7 T
(b) 3 × 10-7 T
(c) 6 × 10-7 T
(d) 12 × 10-7 T
(e) 20 × 10-7 T
(b) 1 × 10-9 T in the +y direction
(c) 2 × 10-9 T in the +y direction
(d) 1 × 10-9 T in the +x direction
(e) 2 × 10-9 T in the -y direction
(e) There is no magnetic field there.
(b) qμ0Iv / 2mR in the -y direction
(c) qμ0Iv / 2mR out of the page
(d) qμ0Iv / 2mR in the +y direction
(e) qμ0Iv / 2mR into the page
Which one of the following is true?
(a) The needles will not deflect.
(b) The needles will deflect in opposite directions.
(c) Both the needles will deflect in the same direction.
A mass spectrometer analyzes the elemental composition of a sample by
sending it through a magnetic field. In the figure below, an unknown
chemical compound traveling at velocity v through a magnetic
field B = 1 T pointing into the page is deflected to the right,
tracing a circular path of radius R = 10 cm. An analyzer
collects the molecules.
What is the sign of the charge?
(a) 102 m/s
(b) 103 m/s
(c) 104 m/s
(d) 106 m/s
(e) 108 m/s
(a) 0.05 m
(b) 0.25 m
(c) 0.5 m
(d) 1 m
(e) 2 m