This exam consists of 28 questions; 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 122. The exam period was 90 minutes; the
mean was 104.8; the median was 108. Click here to see
of the formula sheet that came with the exam.
An object of 2 cm height is at a position 6 cm away from a spherical
concave mirror. The radius of curvature of the mirror is 8 cm. The
locations of the center of curvature (C) and the focal point (F) are
How far is the image from the mirror?
(a) 4 cm
(b) 6 cm
(c) 8 cm
(d) 10 cm
(e) 12 cm
(a) 1 cm
(b) 2 cm
(c) 4 cm
(d) 8 cm
(e) 16 cm
(a) upright relative to the object.
(b) inverted relative to the object.
(a) closer to the mirror.
(b) farther from the mirror.
(a) at point F.
(b) at point C.
(c) such a point does not exist.
What is the maximum value of θ for which no light emerges into
the air outside the fiber?
A person 2 m high stands at the edge of a swimming pool 3 m deep,
looking for a lost watch on the bottom of the pool. The watch is
located a distance x from the edge of the pool. The actual ray which
travels from the watch to the person’s eye emerges from the water 1m
from the edge of the pool. See the figure.
Find the angle θ. This is the angle between the ray emerging
in air and the normal to the pool surface.
(a) 0.82 m
(b) 1.69 m
(c) 2.07 m
(d) 3.61 m
(e) 4.34 m
(a) 2.5 m
(b) 5.0 m
(c) 7.5 m
What thickness should the MgF2 layer be in order to make an
anti-reflection (AR) coating, so that none of the 532 nm light is
reflected from the surface? An AR coating requires destructive
interference between the light reflected from the air / MgF2
interface and light reflected from the MgF2 / glass
(a) 12 nm
(b) 250 nm
(c) 45 nm
(d) 120 nm
(e) 96 nm
Light is incident from the horizontal direction. It goes through the
prism and emerges back into air, at an angle θ, measured with
respect to the normal of the second surface of the prism. Find
An object is placed an unknown distance (x cm) in front of a convex
mirror with a focal length f = -8 cm. The locations of the focal point
(F) and the center of curvature (C) are shown.
The image is always
(a) closer to the mirror than the object.
(b) farther from the mirror than the object.
(a) 6 cm
(b) 8 cm
(c) 10 cm
(d) 12 cm
(e) 16 cm
What is the correct equation to use for destructive interference
between the two paths? In these equations, m is an integer.
(a) 2 r – L = mλ
(b) 2 r – L = (m+1/2) λ
Two lenses are separated by 16 cm. Both Lens #1 and Lens #2 are
converging lenses and have a focal length of 5 cm. An object (arrow) is
located 10 cm to the left of Lens #1.
If lens #2 were not present, the image formed by lens #1 would
(a) 5 cm to the right of lens #1.
(b) 10 cm to the right of lens #1.
(c) 15 cm to the right of lens #1.
(d) 20 cm to the right of lens #1.
(e) 25 cm to the right of lens #1.
(a) 25 cm to the left of lens #2
(b) 15 cm to the left of lens #2
(c) 10 cm to the left of lens #2
(d) 20 cm to the right of lens #2
(e) 30 cm to the right of lens #2
(a) inverted relative to the object.
(b) upright relative to the object.
A glass cell filled with a gas of atoms emits light onto a
diffraction grating, as in the diagram below. The screen is 1 m from
the grating, and the bright fringes are used to identify the atoms in
the gas and to learn about the electronic structure of the atoms.
A grating with 1200 lines/cm is used, and the first order bright
fringe appears at a distance y = 9.4 cm above the center of the screen.
If Cs atoms emit light at 852 nm, Rb atoms at 780 nm, and Na atoms at
589 nm, which type of atom is in the glass cell?
(a) 8.2 nm
(b) 15 nm
(c) 42 nm
(d) 0.35 nm
(e) 78 nm
Light with wavelength 633 nm from a laser is incident on a slit with
diameter 1 cm. The light is projected onto a special mirror designed by
Jim Faller that was left on the moon 3.77x108 m away from the
slit by astronauts.
Which one of the following diagrams best represents the intensity
profile of the light at the moon?
(a) 1.0 μm
(b) 48 km
(c) 1.0 cm
(d) 56 km
(e) 1.0 m
Electromagnetic waves with a 517 m wavelength are emitted in
phase from two radio towers that are 3 km apart as in the figure
below. The radio towers are located at points D and E,
and someone is trying to pickup the radio station at point A.
The reception will be best when the transmissions from D and
E constructively interfere at A. For what minimum
distance y greater than zero does this occur?
(a) 1.75 km
(b) 2.07 km
(c) 0.95 km
(a) 259 m
(b) 3.04 m
(c) 117 m
(d) 890 m
(e) 1000 m
Two flat pieces of quartz are separated by an air gap of width
d. Light from a laser with a 780 nm wavelength (in air) travels
in the quartz and hits the quartz/air interfaces at normal incidence.
Which of the following is the minimum separation d for which the
light reflected from the two quartz/air surfaces will destructively
(a) 187 nm
(b) 390 nm
(c) 125 nm
(d) 893 nm
(e) 795 nm
(a) 77 nm
(b) 12 nm
(c) 130 nm
(d) 250 nm
(e) 170 nm