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 109.
The exam period was 90 minutes; the average score was 70.5; the median
score was 71. Click here to see page1
page2 of the formula sheet that came
with the exam.
Consider the following arrangement of 4 polarizers. The first has a
horizontal transmission axis, the second is oriented at 30° with
respect to the horizontal, the third at 60° to the horizontal, and
the fourth at 90° to the horizontal. The light incident on the
first polarizer from the left is unpolarized.
The ratio of the final intensity of the transmitted light to the
intensity of the incident light is:
(b) remain the same.
(a) larger by a factor of 2.
(b) smaller by a factor of 1/2.
(c) larger by a factor of 1/cos230°.
(d) smaller by a factor of cos230°.
(e) the same as in the original situation.
(a) right circularly polarized.
(b) left circularly polarized.
A laser sends a beam of light from water toward a plastic slab at the
surface of the water. Above the plastic slab there is air.
What is the maximum value of the angle θ that the laser
beam can make with the vertical and still have the beam of light emerge
into the air above the plastic?
(a) 2.73 × 10-10 s
(b) 3.27 × 10-10 s
(c) 4.49 × 10-10 s
(d) 4.73 × 10-10 s
(e) 5.97 × 10-10 s
(a) 63.3 μH
(b) 126.7 μH
(c) 190.0 μH
(d) 253.3 μH
(e) 316.6 μH
A typical electric guitar pickup consists of a coil of several
thousand turns of very thin, enamel-coated copper wire wound around a
fiber bobbin holding 6 rod-shaped permanent magnets. The figure below
shows the 3 (neck, middle, bridge) pickups from a vintage 1959 Fender
'Stratocaster' guitar. A simplified model of an electric guitar pickup
is the so-called RLC 'tank' circuit - as shown in the circuit
diagram below on the right. The '59 Strat pickup coil has an inductance
L = 2.6 H, in series with a resistance R = 5.5 KΩ,
and a small capacitance C = 10-10 F in parallel with
L and R, as shown. The electric guitar pickups are
mounted in proximity to the 6 strings of the electric guitar,
magnetizing them. When a magnetized guitar string vibrates, the
magnetic flux Φm in the pickup coil varies in time
with the string vibrations, inducing a small EMF,
V(t), in the electric guitar pickup, which is then
amplified in a guitar amplifier to produce an audible sound at the
frequency of vibration of the guitar string!
The impedances, Z(ω), of the electric guitar pickup
at ω = 0 and at ω = ∞ are:
(a) Z(ω=0) = 0 ohms and Z(ω=∞) = 0 ohms
(b) Z(ω=0) = 0 ohms and Z(ω=∞) = R ohms
(c) Z(ω=0) = R ohms and Z(ω=∞) = 0 ohms
(a) fo = 9.9 × 103 Hz
(b) fo = 6.2 × 104 Hz
(c) fo = 7.1 × 104 Hz
This question and the next two refer to this situation:
A series RLC circuit is shown in the figure on the right The
resistance R = 200 Ω, inductance L = 2 H and
capacitance C = 2 μF.
The instantaneous voltage, V(t), of the sine-wave
generator and instantaneous current, I(t), flowing through the
RLC circuit are 90° out of phase with each other at the resonant
frequency, fo, of the series RLC circuit.
The voltage amplitude VC across the capacitor at
the resonant frequency, fo, of the series RLC circuit
(a) 100 V
(b) 500 V
(c) 1000 V
(a) 0.0 J
(b) 0.35 J
(c) 0.50 J
(d) 0.71 J
(e) 1.00 J
A sinusoidally-varying voltage V(t) =
Vosinωt with amplitude
Vo = 10 V and frequency of f =
ω/(2π) = 100 Hz is impressed across the plates of
a circular-shaped parallel plate air-gap capacitor of radius a =
1.0 cm and plate separation d= 0.01 mm.
The amplitude of Maxwell's displacement current ID
flowing across the gap between the plates of this capacitor is:
(a) 0.28 × 10-6 A
(b) 1.75 × 10-6 A
(c) 3.50 × 10-6 A
(d) 6.30 × 10-6 A
(e) 9.45 × 10-6 A
(a) decrease by a factor of four.
(b) decrease by a factor of two.
(c) remain the same.
(d) increase by a factor of two.
(e) increase by a factor of four.
A plane electromagnetic wave is propagating in free space. The
instantaneous electric field vector is given by
electric field amplitude associated with this plane wave is
Eo = 100 V/m.
The corresponding instantaneous magnetic field vector is given by:
(a) B(r,t) = Bocos(kz+ωt) x
(b) B(r,t) = -Bosin(kz+ωt) x
(c) B(r,t) = -Bocos(kz+ωt) y
(d) B(r,t) = Bosin(kz+ωt) y
(e) B(r,t) = -Bosin(kz+ωt) z
(a) 8.85 × 10-12 T
(b) 3.33 × 10-7 T
(c) 100 T
(a) 6.6 watts/m2
(b) 13.3 watts/m2
(c) 26.6 watts/m2
(a) UA = ¼ UB
(b) UA = ½ UB
(c) UA = UB
(d) UA = 2 UB
(e) UA = 4 UB
In the circuit below, V = 6 volts, R = 10 ohms,
L = 100 mH. The switch has been open for a long time. Then, at
time t = 0, the switch is closed.
What is the current I∞ through L for
t → ∞ ?
(a) 0.0 A
(b) 0.3 A
(c) 0.6 A
(a) R / L
(b) R / (2L)
(c) L / R
(d) 2L / R
(e) L / (2R)
Calculate the impedance, Z, of the circuit.
(a) 7.48 Ω
(b) 10.14 Ω
(c) 15.24 Ω
(d) 22.42 Ω
(e) 32.24 Ω
(a) VAC and VR are in phase.
(b) VAC leads VR.
(c) VAC lags VR.
(a) 0.005 A
(b) 0.100 A
(c) 0.500 A
(d) 1.000 A
(e) 4.000 A
(a) VC(t1) > VR(t1) >
(b) VC(t1) > VL(t1) >
(c) VR(t1) > VC(t1) >
(d) VR(t1) > VL(t1) >
(e) Cannot be determined from the information given.