Q1) Diffraction occurs when light passes a:
1) pinhole.
2) narrow slit.
3) wide slit.
4) sharp edge.
5) all of the above
Q2) Diffraction plays an important role in which of the following
phenomena?
1) The sun appears as a disk rather than a point to the naked eye
2) Light is bent as it passes through a glass prism
3) A cheerleader yells through a megaphone
4) A farsighted person uses eyeglasses of positive focal length
5) A thin soap film exhibits colors when illuminated with white light
Q3) No fringes are seen in a single-slit diffraction pattern if:
1) the screen is far away
2) the wavelength is less than the slit width
3) the wavelength is greater than the slit width
4) the wavelength is less than the distance to the screen
5) the distance to the screen is greater than the slit width
Q4) The pattern on the screen is due to a narrow
slit that is
1) horizontal
2) vertical
Q5) Diffraction occurs when light passes through a single slit.
Rank the following three choices in decreasing order, according to
the extent of the diffraction that occurs (largest diffraction first).
A – blue light, narrow slit
B – red light, narrow slit
C – blue light, wide slit
1) A, B, C
4) A, C, B
2) B, A, C
5) B, C, A
3) C, A, B
Q6) You are conducting a single-slit diffraction experiment with
light of wavelength . What appears, on a distant viewing screen,
at a point at which the top and bottom rays through the slit have a
path length difference equal to (a)  and (b) 4.?
1)
2)
3)
4)
(a) dark fringe
(a) dark fringe
(a) approximately a bright fringe
(a) approximately a bright fringe
(b) dark fringe
(b) approximately a bright fringe
(b) approximately a bright fringe
(b) dark fringe
Q7) The diagram shows a single slit with the direction to a point P on a
distant screen shown. At P, the pattern has its second minimum (from its
central maximum). If X and Y are the edges
of the slit, what is the path length difference (PX) - (PY)?
1) λ/2
2) λ
3) 3λ/2
4) 2λ
5) 5λ/2
Q8) The diagram shows a single slit with the direction to a point P on a
distant screen shown. At P, the pattern has its maximum nearest the central
maximum. If X and Y are the edges of the
slit, what is the path length difference (PX) - (PY)?
1) λ/2
2) λ
3) 3λ/2
4) 2λ
5) 5λ/2
Q9) A student wishes to produce a single-slit diffraction pattern in
a ripple tank experiment. He considers the following parameters:
1. frequency
2. wavelength
3. water depth
4. slit width
Which two of the above should be decreased to produce more
bending?
1) 1, 3
4) 2, 4
2) 1, 4
5) 3, 4
3) 2, 3
Q10) The intensity at a secondary maximum of a single-slit diffraction
pattern is less than the intensity at the central maximum chiefly because:
1) some Huygens wavelets sum to zero at the secondary maximum but not
at the central maximum
2) the secondary maximum is further from the slits than the central
maximum and intensity decreases as the square of the distance
3) the Huygens construction is not valid for a secondary maximum
4) the amplitude of every Huygens wavelet is smaller when it travels to a
secondary maximum than when it travels to the central maximum
5) none of the above
Q11) In a single-slit diffraction pattern, the central maximum is
about twice as wide as the other maxima. This is because:
1) half the light is diffracted up and half is diffracted down
2) the central maximum has both electric and magnetic fields
present
3) the small angle approximation applies only near the central
maximum
4) the screen is flat instead of spherical
5) none of the above
Q12) Light of frequency f illuminating a long narrow slit produces
a diffraction pattern. (a) If we switch to light of frequency 1.3 f,
does the pattern expand away from the center or contract toward
the center? (b) Does the pattern expand or contract if, instead, we
submerge the equipment in clear corn syrup?
1)
2)
3)
4)
(a) expand
(a) expand
(a) contract
(a) contract
(b) expand
(b) contract
(b) contract
(b) expand
Q13) We produce a diffraction pattern on a viewing screen by
means of a long narrow slit illuminated by blue light. Does the
pattern expand away from the bright center or contract toward it if
we (a) switch to yellow light or (b) decrease the slit width?
1) (a) expand
2) (a) expand
3) (a) contract
4) (a) contract
(b) expand
(b) contract
(b) contract
(b) expand
Q14) Violet light of wavelength  passes through a single slit of
width D and forms a diffraction pattern on a screen. If the violet
light is replaced with red light of wavelength 2, the original
pattern on the screen is reproduced if the slit width is changed to
1) D/2
2) D/4
3) 2D
4) 4D
5) no change necessary.
Q15) Blue light of wavelength passes through a single slit of
width a and forms a diffraction pattern on a screen. If the blue light
is replaced by red light of wavelength 2, the original diffraction
pattern is reproduced if the slit width is changed to
1) a/4.
2) a/2.
3) No change is necessary.
4) 2a.
5) 4a.
Q16) A laser shines through a single slit and a diffraction pattern is seen
on a screen. Then a single thing about the experiment is changed , so that
the pattern looks similar, but covers a smaller portion on the screen.
Select all answers that could account for the smaller pattern.
1) The screen was moved further away from the slit.
2) The wavelength of the laser light was decreased.
3) The slit was changed to a smaller width slit.
4)The laser was moved closer to the slit.
1) 2, 3
4) No answer is correct
2) 1, 2, 3, 4
5) some other answer.
3) 2, 3, 4
Q17) Two wavelengths, 650 and 430 nm, are used separately in a
single-slit diffraction experiment. The figure shows the results as
graphs of intensity I versus angle  for the two diffraction patterns.
If both wavelengths are then used simultaneously, what color will
be seen in the combined diffraction pattern at (a) angle A and (b)
angle B?
1) (a) red
(b) violet
2) (a) violet (b) red
Q18) Imagine holding a circular disk in a beam of monochromatic
light. If diffraction occurs at the edge
of the disk, the center of the shadow of
the disk is
1) a bright spot.
2) darker than the rest of the shadow.
3) bright or dark, depending on the
distance between the disk and the screen.
4) as dark as the rest of the shadow, but less dark than if there is no
diffraction.
Q19) In a double-slit diffraction experiment the number of
interference fringes within the central diffraction maximum can be
increased by:
1) increasing the wavelength
2) decreasing the wavelength
3) decreasing the slit separation
4) increasing the slit width
5) decreasing the slit width
Q20) Consider a double-slit experiment where d/a = 4. How many
bright fringes are within the central peak of the diffraction
envelope?
1) 3
2) 4
3) 7
4) 8
5) 9
Q21) Two slits in an opaque barrier each have a width of 0.020mm
and are separated by 0.050mm. When coherent monochromatic
light passes through the slits the number of interference maxima
within the central diffraction maximum:
1) is 1
2) is 2
3) is 4
4) is 5
5) cannot be determined unless the wavelength is given
Q22) When 450-nm light is incident normally on a certain doubleslit system the number of interference maxima within the central
diffraction maximum is 5. When 900-nm light is incident on
the same slit system the number is:
1) 2
2) 3
3) 5
4) 9
5) 10
Q23) The figure below shows the bright fringes that lie within the
central diffraction envelope in two-slit diffraction experiments
using the same wavelength of light. Are (a) the slit width a, and (b)
the slit separation d in experiment B greater than, or the same as
those in experiment A?
1) (a) greater than
2) (a) greater than
3) (a) less than
4) (a) less than
(b) greater than
(b) less than
(b) less than
(b) greater than
Q24) The figure below shows the bright fringes that lie within the
central diffraction envelope in two-slit diffraction experiments
using the same wavelength of light. Is the ratio d/a in experiment B
greater than, or the same as those in experiment A?
1) greater than
2) less than
Q25) A light spectrum is formed on a screen using a diffraction
grating. The entire apparatus (source, grating and screen) is now
immersed in a liquid of refractive index 1.33. As a result, the
pattern on the screen:
1) remains the same
2) spreads out
3) crowds together
4) becomes reversed, with the previously blue end becoming red
5) disappears because the refractive index isn’t an integer
Q26) In order to obtain a good single-slit diffraction pattern, the
slit width could be:
1) λ
2) λ/10
3) 10λ
4) 104λ
5) λ/104
Q27) The figure below shows a red line and a green line of
the same order in the pattern produced by a diffraction
grating. If we increased the grating spacing d, would the
lines shift to the right, shift to the left, or remain in place.
1) to the right
2) to the left
3) remain in place
Q28) 600-nm light is incident on a diffraction grating with a ruling
separation of 1.7 × 10-6 m. The second order line occurs at a
diffraction angle of:
1) 0
2) 10
3) 21
4) 42
5) 45
Q29) A diffraction grating is illuminated with yellow light at normal
incidence. The pattern seen on a screen behind the grating consists
of three yellow spots, one at zero degrees (straight through) and one each
at ±45°.You now add red light of equal intensity, coming in the same
direction as the yellow light. The new pattern consists of
1) red spots at 0° and ±45°.
2) yellow spots at 0° and ±45°.
3) orange spots at 0° and ±45°.
4) an orange spot at 0°, yellow spots at ±45°, and red spots slightly farther out.
5) an orange spot at 0°, yellow spots at ±45°, and red spots slightly closer in.
Q30) The figure below shows lines of two orders produced by
a single diffraction grating using light of two wavelengths,
both in the red region of the spectrum. Is the center of the
diffraction pattern to the left or to the right?
1) to the left
2) to the right
Q31) The figure shows lines of different orders produced by a diffraction
grating in monochromatic red light. (a) Is the center of the pattern to the
left or right? (b) If we switch to monochromatic green light, will the halfwidths of the lines then produced in the same orders be greater than, less
than, or the same as the half-widths of the lines shown?
1) (a) left (b) greater than
2) (a) left (b) less than
3) (a) right (b) greater than
4) (a) right (b) less than
5) (a) right (b) the same as
Q32) The “D-line” in the spectrum of sodium is a “doublet” with
wavelengths 589.0 nm and 589.6 nm. What is the minimum
number of slits in the grating necessary to just resolve this doublet
in the second order?
1) 982
2) 491
3) 245
4) 123
5) 61
Q33) Monochromatic light is normally incident on a diffraction
grating. The mth order line is at a diffraction angle θ and has
width w. A wide single slit is now placed in front of the grating
and its width is then slowly reduced. As a result:
1) both θ and w increase
2) both θ and w decrease
3) θ remains the same and w increases
4) θ remains the same and w decreases
5) θ decreases and w increases
Q34) Suppose that you can barely resolve two red dots, owing to
diffraction by the pupil of your eye. If we increase the general
illumination around you so that the pupil decreases in diameter,
does the resolvability of the dots improve or diminish? Consider
only diffraction. (You might experiment to check your answer.)
1) improve
2) diminish
Q35) Two nearly equal wavelengths of light are incident on an Nslit grating. The two wavelengths are not resolvable. When N is
increased they become resolvable. This is because:
1) more light gets through the grating
2) the lines get more intense
3) the entire pattern spreads out
4) there are more orders present
5) the lines become more narrow
Q36) The widths of the lines produced by monochromatic light
falling on a diffraction grating can be reduced by:
1) increasing the wavelength of the light
2) increasing the number of rulings without changing their spacing
3) decreasing the spacing between adjacent rulings without
changing the number of rulings
4) decreasing both the wavelength and the spacing between rulings
by the same factor
5) increasing the number of rulings and decreasing their spacing so
the length of the grating remains the same
Q37) Two stars that are close together are photographed through a
telescope. Which situation would results in the most clearly
separated images of the stars?
1) small lens, red stars
2) small lens, blue stars
3) large lens, red stars
4) large lens, blue stars
Q38) The headlights of a car are 1.6 m apart and produce light of
wavelength 575 nm in vacuum. The pupil of the eye of the
observer has a diameter of 4.0 mm and a refractive index of 1.4.
What is the maximum distance from the observer that the two
headlights can be distinguished?
1) 8.0 km
2) 9.1 km
3) 11 km
4) 13 km
5) 16 km
Q39) A spy satellite is in orbit at a distance of 1.0 × 106 m above the
ground. It carries a telescope that can resolve the two rails of a
railroad track that are 1.4 m apart using light of wavelength 600 nm.
Which one of the following statements best describes the diameter
of the lens in the telescope?
1) It is less than 0.14 m.
2) It is greater than 0.14 m and less than 0.23 m.
3) It is greater than 0.23 m and less than 0.35 m.
4) It is greater than 0.35 m and less than 0.52 m.
5) It is greater than 0.52 m.
Q40) An x-ray beam of wavelength 3.0  10-11m is incident on a
calcite crystal of lattice spacing 0.3 nm. The smallest angle
between crystal planes and the x-ray beam that will result in
constructive interference is:
1) 2.87o
2) 5.73o
3) 11.63o
4) 23.27o
5) none of the above
Q41) Which of the following is true for Bragg diffraction but not
for diffraction from a grating?
1) Two different wavelengths may be used
2) For a given wavelength, a maximum may exist in several directions
3) Long waves are deviated more than short ones
4) There is only one grating spacing
5) Maxima occur only for particular angles of incidence