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 112.
The exam period was 90 minutes; the mean score was 83.8; the median was
86. Click here to see page1
page2 of the formula sheet that came
with the exam.
Some helpful information:
• A physics 102 light bulb acts just like a resistor: its resistance
is constant, independent of the current flowing through the light bulb.
The bulb's brightness increases with increasing current.
• 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.
A pair of conducting rails is connected to a resistor and a 5 V battery as
shown in the following figure. A movable conducting bar is placed in contact
with the rails. Initially the position of the conducting bar is held fixed.
The entire device lies in a plane perpendicular to a magnetic field of
strength 0.5 T.
The conducting bar is now moved slowly to the
right. Relative to the current that had been flowing through
the resistor while the bar was stationary, the current I
(a) 0.625 m/s
(b) 2.5 m/s
(c) 12.5 m/s
(d) 40 m/s
(e) 62.5 m/s
A conducting metal band containing a 5 Ω resistor is formed into a
circle of radius R = 2 m as shown in the diagram. The band passes
through a current sensor that also controls the strength of an adjustable,
externally created magnetic field. (The electromagnet that creates this
uniform field is not shown in the diagram.) The circle always lies in the
plane of the paper, perpendicular to the magnetic field.
The current sensor/magnet power supply is programmed to adjust the
external magnetic field so that a constant current of 0.1 A flows around the
loop. At time t = 0 the magnetic field happens to have the value
B = 0. What is the value of B at t = 1 second?
(a) B = 0.040 T
(b) B = 0.100 T
(c) B = 0.314 T
(d) B = 1.687 T
(e) B = 2.000 T
(a) ΔB/Δt would need to increase by a factor of 2.
(b) ΔB/Δt would need to increase by a factor of 4.
(c) ΔB/Δt would need to decrease by a factor of 2.
(d) ΔB/Δt would need to decrease by a factor of 4.
(e) ΔB/Δt would not need to change.
A rectangular loop (made from a single turn of wire) has sides a =
0.2 m and b = 0.1 m. The coil rotates about the y axis with
angular velocity Ω = 20 rad/s in a uniform magnetic field
B = 0.05 T that is parallel to the x axis. A light
bulb with resistance 12 Ω is connected in series with the loop as shown
in the diagram.
What is the maximum current that flows through the light bulb?
(a) 65.8 mA
(b) 12.2 mA
(c) 1.67 mA
(a) 320 Hz
(b) 2010 Hz
(c) 50.9 Hz
The peak power delivered to the resistor attached to the
transformer's secondary is 75 W. What is the signal generator's peak
(a) 1.5 V
(b) 5.0 V
(c) 20.4 V
(d) 3750 V
(e) 36000 V
What is the inductance of this solenoid?
(a) 0.612 H
(b) 62000 H
(c) 1.344 mH
In order to make the maximum value of VL become
less than the maximum value of VC one
(a) increase the maximum voltage of the sine wave generator.
(b) decrease the frequency of the sine wave generator.
(c) increase the value of R used in the circuit.
In the circuit shown the switch S is initially open and the two
capacitors are fully discharged.
At time t = 0 the switch S is closed. What is the current
through the resistor R immediately after S is closed?
(a) 10000 A
(b) 2.5 mA
(c) 0.0025 mA
(d) 2.5 A
(e) 10 mA
(a) I(25 msec) / I(0) = 0.361
(b) I(25 msec) / I(0) = 0.010
(c) I(25 msec) / I(0) = 0.650
(d) I(25 msec) / I(0) = 0.249
(e) I(25 msec) / I(0) = 0.189
In the circuit shown the switch S1 is initially open and
the capacitor C is fully discharged.
Switch S1 is now closed. Which one of the following
represents the correct time-dependence of the current through resistor
(a) 1.5 ms
(b) 6 ms
(c) 45 ms
(d) 18 μs
(e) 2.2 s
A charged particle, q, is moving in a uniform magnetic field and
travels in a circle of radius R, as shown.
What is the sign of q?
(a) 2.26 ×10-11 kg
(b) 3.02 ×10-13 kg
(c) 2.46 × 10-12 kg
A proton with charge q = +1.6 × 10-19 C and mass
m = 1.67 × 10-27 kg is initially traveling
horizontally in a magnetic field with velocity v = 800 m/s, as shown
below. The proton experiences a downward acceleration due to gravity of
g = 9.8 m/s2. If the magnetic field were zero, the proton
would follow the downward, parabolic trajectory shown in the dashed line.
How large a magnetic field would have to be applied to force the proton to
move in a straight line?
(a) 5 × 10-8 T
(b) 4.44 ×10-12 T
(c) 1.5 T
(d) 1.28 ×10-10 T
(e) 23 mT
How large would the current have to be to lift the cable off the ground?
Recall, g = 9.8 m/s2.
(a) 2.2 × 106 A
(b) 18600 A
(c) 5325 A
(d) 340 A
(e) 52.9 A
In an RLC circuit, the following three elements are connected in
series: a 10 mH inductor L, a 20 Ω resistor R, and a 120
μF capacitor C. The AC generator has a peak voltage of 1V, and a
frequency of 50 Hz. Assume the resistance of the inductor is zero.
Across which of the following elements of the circuit is the maximum
voltage drop the greatest?
The following drawing indicates the voltage across the circuit
elements as a function of time. The voltage drop across the resistor is
labeled A (solid line). The voltage drops across which elements are
shown by the dashed and dotted lines?
(a) C = generator; B = capacitor
(b) C = inductor; B = capacitor
(c) C = inductor; B = generator
(a) 1.29 A
(b) 0.39 A
(c) 32.5 mA
(d) 92.8 mA
(e) 0.21 mA
(e) 100. 3°
(a) The current leads the generator voltage.
(b) The generator voltage leads the current.
(a) 42.0 Hz
(b) 145 Hz
(c) 2.34 kHz
(c) remain the same.