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 107.
The exam period was 90 minutes; the mean was 63.7; the median was 64.
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.
Which one of the following phasor diagrams can
correctly represent the voltages across the inductor, resistor, and
capacitor at some particular time t > 0 ?
Which one of the arrows below best indicates the
direction in which the wave is traveling as it passes
through this point in space?
(a) In an electromagnetic wave the oscillations of the electric field differ
in phase from the oscillations of the magnetic field by 1/4 cycle.
(b) An electromagnetic wave is a transverse wave because the
electric and magnetic field are both perpendicular to the wave's
direction of travel.
(c) Light from a distant star found to be moving away from the
Earth at half the speed of light is Doppler shifted towards
shorter wavelengths when viewed from the Earth.
(a) 3.33 × 10-10 V/m
(b) 0.1 V/m
(c) 30 MV/m
(a) Erms = 377 V/m
(b) Erms = 8.99 MV/m
(c) Erms = 120 V/m
(d) Erms = 5.37 kV/m
(e) Erms = 6.13 kV/m
(a) In an electromagnetic wave the energy density of the magnetic field
cancels the energy density of the magnetic field so that the net energy
density in any electromagnetic wave is zero.
(b) The relationship between the energy density uB of the
magnetic field in an electromagnetic wave and the energy density
uE of the electric field is uB =
(c) The average energy density in an electromagnetic wave whose electric and
magnetic fields vary sinusoidally with time depends on the amplitudes of
the wave's electric and magnetic fields but not on the fields'
If the intensity of light leaving the last filter in the four-filter
stack is Ifour and the intensity of light leaving the
last filter in the seven-filter stack is Iseven what
is the ratio Ifour / Iseven?
(a) Ifour / Iseven = 0.51
(b) Ifour / Iseven = 0.64
(c) Ifour / Iseven = 0.80
(d) Ifour / Iseven = 1.00
(e) Ifour / Iseven is undefined since it is 0/0
How many reflected images of the object are visible to the
Which one of the following pairs of values of darc
and dmatch will ignite the match most rapidly?
(a) darc = 5.00, dmatch = 5.00
(b) darc = 3.14, dmatch = 3.14
(c) darc = 2.50, dmatch = 2.50
What distance must separate the two lenses so that the rays out of the
divergent lens are parallel?
(a) 20 cm
(b) 52.5 cm
(c) 95 cm
(d) 105 cm
(e) 500 cm
The angle θ is:
A ray of white light passes through a glass prism, dispersing into
the colors of the rainbow. The index of refraction of the prism
nglass = 1.33 at the wavelength of red
Calculate the angle the red ray of light makes relative to the
(a) nred < nblue
(b) nred > nblue
(a) less than 1.33
(b) 1.414 or greater
(c) The light can never be internally reflected.
A magnifying glass is used to read the fine print on a document. The
focal length of the lens is f = 10 mm.
At what distance from the lens must the document be held in order to
obtain an image magnified by 5 that is NOT
(a) 1.7 mm
(b) 8 mm
(c) 12 mm
(d) 40 mm
(e) 60 mm
We learned in class that mirrors can be used to focus light. The
same principle also applies to sound.
You are eavesdropping on your neighbor's conversation using a concave
spy dish of focal length f = 50 cm to focus his voice onto a
microphone. As shown in the figure, the neighbor is 20 m away from the
dish, and his mouth is 1.7 m above the ground. The center of the dish is
at a height of 1m from the ground. Ignore any effects from
You're adjusting the distance between the microphone and the dish.
At what height from the ground should you ideally place
(a) 104.4 cm
(b) 101.8 cm
(c) 100.0 cm
(d) 98.2 cm
(e) 95.6 cm
(a) Move the microphone to the right and up.
(b) Move the microphone to the right and down.
(c) Keep the microphone where it is.
(d) Move the microphone to the left and up.
(e) Move the microphone to the left and down.
Light of 500 nm wavelength due to a light source far away is
impingent on the slits from the left. The two slits are separated by
0.01 mm, and an interference pattern is formed on a screen placed a
distance L from the slits. The first minimum of
the interference pattern is found to be 10 cm above the center of the
What is the distance L between the slits and the screen?
(a) 2.5 meter
(b) 4.0 meter
(c) 10 meter
(a) Move up by 2 cm.
(b) Move up by 6 cm.
(c) Move down by 2 cm.
(d) Move down by 6 cm.
(e) It does not move
A thin layer of oil with index of refraction n1 = 1.45 is
placed on top of a glass slab with index of refraction n2 =
1.5. Light with a wavelength of 532 nm is incident on the thin oil film
(thickness t) nearly normal to the surface (note that
deviation from the normal is exaggerated!). An observer is right above the
film looking at the light reflected from the air-oil interface (labeled 1)
and reflected from the oil-glass interface (labeled 2).
What is the minimal thickness t of the oil layer that would
allow destructive interference between the reflections off the two
(a) 91.7 nm
(b) 133 nm
(c) 183 nm
(d) 266 nm
(e) 532 nm
(a) constructive interference
(b) destructive interference
These intensity distributions were observed from two different
multiple slit devices illuminated by light of the same wavelength.
Which device has the larger number of slits?
(a) The patterns would expand (larger spacing between peaks).
(b) The patterns would compress (smaller spacing between peaks).
(c) The patterns would not shift (same spacing) but will become sharper.