Q1) Two speakers, A and B, are separated by a distance of
2.0 m. The speakers emit sound waves of wavelength
0.25 m that are exactly out of phase. What type of
interference will there be at a point 0.5 m to the right of
speaker A?
1) constructive interference
2) destructive interference
Q2) A laser emits light with a wavelength of 600 nm. A beam
splitter and mirrors are used to direct the light to a receiver along
two different paths. If the length of path one is 2.40 µm and the
length of path two is 1.20 µm, the waves arrive
1) in phase.
2) out of phase, but not by  radians.
3)  radians out of phase.
Q3) The light waves of the rays in the figure have the same
wavelength and amplitude and are initially in phase. (a) If 7.60
wavelengths fit within the length of the top material and 5.50
wavelengths fit within that of the bottom material, which material
has the greater index of refraction?
1) top
2) bottom
Q4) When an electromagnetic wave travels from a vacuum to a
material with an index of refraction n > 1, what changes?
1) the wavelength of the EM wave
2) the frequency of the EM wave
3) both the wavelength and the frequency
4) neither the wavelength or the frequency
Q5) The figure below shows four situations in which light reflects
perpendicularly from a thin film of thickness L, with indexes of
refraction as given. For which situations will the film be dark if the
path length difference 2L causes a phase difference of 0.5
wavelengths.
1) only 1
2) only 4
3) 1 and 4
4) 2 and 3
Q6) Monochromatic light, at normal incidence, strikes a thin film
in air. If λ denotes the wavelength in the film, what is the thinnest
film in which the reflected light will be a maximum?
1) Much less than λ
4) 3λ/4
2) λ/4
5) λ
3) λ/2
Q7) A lens with a refractive index of 1.5 is coated with a material of
refractive index 1.2 in order to minimize reflection. If λ denotes
the wavelength of the incident light in air, what is the thinnest
possible such coating?
1) 0.5λ
2) 0.416λ
3) 0.3λ
4) 0.208λ
5) 0.25λ
Q8) A glass (n = 1.6) lens is coated with a thin film (n = 1.3) to
reduce reflection of certain incident light. If λ is the wavelength
of the light in the film, the least film thickness is:
1) less than λ/4
4) λ
2) λ/4
5) more than λ
3) λ/2
2Ln
2
Q9) For which of the situations does the expression   m for
m = 1, 2, 3, … give the wavelengths of the transmitted light that
undergoes fully constructive interference?
1) only a
2) only b
3) a and c
4) b and d
5) none of the above
Q10) Three experiments involving a thin film (in air) are shown. If
t denotes the film thickness and λ denotes the wavelength of the
light in the film, which experiments will produce constructive
interference as seen by the observer? The incident light is nearly
normal to the surface.
1) I only
2) II only
3) III only
4) I and III only
5) II and III only
Q11) A wedge-shaped air space is formed between two flat slabs
of glass. The glass has index of refraction n. The reflected light of
wavelength  forms an interference pattern. What is the condition
for a bright fringe?
1) 2d = m
2) 2d sin = m
3) 2d = (m + ½)
4) 2d sin = (m + ½)
5) None of these/don't know
Q12) Consider two identical microscope slides in air illuminated
with monochromatic light. The bottom slide is rotated
(counterclockwise about the point of contact in the side view) so
that the wedge angle gets a bit smaller. What happens to the
fringes?
1) They are spaced farther apart.
2) They are spaced closer together.
3) They don’t change.
Q13) A liquid of refractive index n = 4/3 replaces the air between a
fixed wedge formed from two glass plates as shown. As a result, the
spacing between adjacent dark bands in the interference pattern:
1) increases by a factor of 4/3
2) increases by a factor of 3
3) remains the same
4) decreases to 3/4 of its original value
5) decreases to 1/3 of its original value
Q14) Which one of the following statements best explains why
interference patterns are not usually observed for light from two
ordinary light bulbs?
1) The two sources are out of phase.
2) The two sources are not coherent.
3) The interference pattern is too small to observe.
4) Light from ordinary light bulbs is not polarized.
5) None of the above
Q15) If two light waves are coherent:
1) their amplitudes are the same
2) their frequencies are the same
3) their wavelengths are the same
4) their phase difference is constant
5) the difference in their frequencies is constant
Q16) Waves from two slits are in phase at the slits and travel to a
distant screen to produce the second minimum of the interference
pattern. The difference in the distance traveled by the waves is:
1) half a wavelength
2) a wavelength
3) three halves of a wavelength
4) two wavelengths
5) five halves of a wavelength
Q17) In a Young’s double-slit experiment the center of a bright
fringe occurs wherever waves from the slits differ in phase by a
multiple of:
1) π/4
2) π/2
3) π
4) 3π/4
5) 2π
Q18) In a Young’s double slit experiment, green light is incident
on the two slits. The interference pattern is observed on a screen.
Which one of the following changes would cause the fringes to be
more closely spaced?
1) Reduce the slit separation distance.
2) Use red light instead of green light.
3) Use blue light instead of green light.
4) Move the screen farther away from the slits.
5) Move the light source farther away from the slits
Q19) A laser shines through a double slit aperture and a 2-slit
interference pattern is observed on a screen. The room is then
filled with water and the experiment is repeated (the laser is waterproof). The separation of intensity maxima on the screen...
1) increases
2) decreases
3) stays the same.
Q20) A two-slit interference pattern is
viewed on a screen. The separation
of the slits, d, is slowly increased.
What happens to the pattern on the
screen?
fringes
d
1) The fringes move closer together.
2) The fringes move further apart.
3) There is no change in the fringe separation.
screen
Q21) In an experiment to measure the wavelength of light using a
double slit, it is found that the fringes are too close together to
easily count them. To spread out the fringe pattern, one could:
1) decrease the slit separation
2) increase the slit separation
3) increase the width of each slit
4) decrease the width of each slit
5) none of these
Q22) White light is passed through a yellow filter and then serves
as the source for a Young’s double-slit experiment. Which of the
following changes would cause the interference pattern to be more
closely spaced?
1) use slits that are closer together
2) use a light source of lower intensity
3) use a red filter instead of a yellow filter
4) use a blue filter instead of a yellow filter
5) move the light source further away from the slits
Q23) (a) How would the pattern of bright and dark fringes
produced in a Young's double slit experiment change in the light
rays coming from both slits had their phases shifted by an amount
equivalent to a half wavelength? (b) How would the pattern
change if the light coming from only one of the slits had its phase
shifted by an amount equivalent to a half wavelength?
1) (a) no change (b) bright and dark fringes interchanged
2) (a) bright and dark fringes interchanged (b) no change
3) none of the above
Q24) A two-slit experiment is performed in the air. Later, the
same apparatus is placed in a vacuum chamber and the experiment
is repeated under a high vacuum. The interference fringes are now
1) more widely spaced.
2) spaced the same.
3) more closely spaced.
Q25) A standard double-slit experiment is modified by placing a
small piece of glass in front the right slit (diagram below). The
effect of the glass is to shift the phase of the light from the right slit
so that the two slits no longer emit wavefronts in sync. Instead, the
right slit emits a wavefront a little later than the left slit. After the
glass is inserted, the intensity pattern on the screen is...
1) unchanged
2) shifts to the right
3) shifts left.
4) None of these.
glass
Q26) In a Young’s double-slit experiment, the separation between
slits is d and the screen is a distance D from the slits. The number
of bright fringes per unit width on the screen is
1) Dd/
4) /Dd
2) D/d
5) d/D
3) D/d
Q27) A double slit is illuminated with monochromatic light of
wavelength 6.00  102 nm. The m = 0 and m = 1 bright fringes are
separated by 3.0 cm on a screen which is located 4.0 m from the
slits. What is the separation between the slits?
1) 4.0  10-5 m
2) 8.0  10-5 m
3) 1.2  10-5 m
4) 1.6  10-5 m
5) 2.4  10-5 m
Q28) A monochromatic light source illuminates a double slit and
the resulting interference pattern is observed on a distant screen.
Let d = center-to-center slit spacing, a = individual slit width,
D = screen-to-slit distance, and L = adjacent dark line spacing in
the interference pattern. The wavelength of the light is then:
1) Ld/D
4) LD/a
2) Ld/a
5) Dd/L
3) da/D
Q29) In a Young’s double-slit experiment, the slit separation is
doubled. To maintain the same fringe spacing on the screen, the
screen-to-slit distance D must be changed to:
1) D/2
2) D /2
3) D2
4) 2D
5) 4D
Q30) One of the two slits in a Young’s experiment is painted over
so that it transmits only one-half the intensity of the other slit. As a
result:
1) the fringe system disappears
2) the bright fringes get brighter and the dark ones get darker
3) the fringes just get dimmer
4) the dark fringes just get brighter
5) the dark fringes get brighter and the bright ones get darker
Q31) In a Young’s double-slit experiment, a thin sheet of mica is
placed over one of the two slits. As a result, the center of the fringe
pattern (on the screen) shifts by an amount corresponding to 30 dark
bands. The wavelength of the light in this experiment is 480 nm and
the index of the mica is 1.60. The mica thickness is:
1) 0.090mm
4) 0.024mm
2) 0.012mm
5) 0.062mm
3) 0.014mm
Q32) What does one observe on the screen in a Young’s
experiment if white light illuminates the double slit instead of light
of a single wavelength?
1) a white central fringe and no other fringes
2) a dark central fringe and a series of alternating white and dark
fringes on each side of the center
3) a white central fringe and a series of colored and dark fringes on
each side of the center
4) a continuous band of colors with no dark fringes anywhere
5) a dark screen since no constructive interference can occur
Q33) In two separate double slit experiments, an interference
pattern is observed on a screen. In the first experiment, violet light
(λ = 754 nm) is used and a second-order bright fringe occurs at the
same location as a third-order dark fringe in the second
experiment. Determine the wavelength of the light used in the
second experiment.
1) 1320 nm
4) 431 nm
2) 862 nm
5) 388 nm
3) 594 nm
Q34) Light is incident on two slits that are separated by 0.2 mm.
The figure shows the resulting interference pattern observed on a
screen 1.0 m from the slits. Determine the wavelength of light
used in this experiment.
1) 0.05 nm
2) 0.50 nm
3) 50 nm
4) 500 nm
5) 5000 nm