Chapter 33: Interference and Diffraction

1
Chapter 33 Interferenceand Diffraction

• Section 33-1 Phase Difference and Coherence

2
A phase shift of 180º occurs when a light wave

1. is transmitted through a boundary surface into a
   medium that is more dense than the medium from
   which the wave came.
2. is transmitted through a boundary surface into a
   medium that is less dense than the medium from
   which the wave came.
3. reflects from the boundary surface of a medium
   that is less dense than the medium in which the
   wave is traveling.
4. reflects from the boundary surface of a medium
   that is more dense than the medium in which the
   wave is traveling.
5. Both c and d are correct.

3
A phase shift of 180º occurs when a light wave

1. is transmitted through a boundary surface into a
   medium that is more dense than the medium from
   which the wave came.
2. is transmitted through a boundary surface into a
   medium that is less dense than the medium from
   which the wave came.
3. reflects from the boundary surface of a medium
   that is less dense than the medium in which the
   wave is traveling.
4. reflects from the boundary surface of a medium
   that is more dense than the medium in which the
   wave is traveling.
5. Both c and d are correct.

4
Which, if any, of the following conditions is not
necessary for the light waves from two sources to
be coherent?

1. They must have the same frequency.
2. They must have the same amplitude.
3. They must have the same wavelength.
4. They must have a constant phase difference.
5. All of these conditions are necessary.

5
Which, if any, of the following conditions is not
necessary for the light waves from two sources to
be coherent?

1. They must have the same frequency.
2. They must have the same amplitude.
3. They must have the same wavelength.
4. They must have a constant phase difference.
5. All of these conditions are necessary.

6
Diffraction of sound waves is more readily
observable than that of light waves because

1. sound waves are longitudinal and not transverse.
2. sound waves have a higher frequency than light
   waves.
3. sound waves have a lower velocity than light
   waves.
4. sound waves have longer wavelengths than do light
   waves.
5. sound waves occur in air and light waves do not.

7
Diffraction of sound waves is more readily
observable than that of light waves because

1. sound waves are longitudinal and not transverse.
2. sound waves have a higher frequency than light
   waves.
3. sound waves have a lower velocity than light
   waves.
4. sound waves have longer wavelengths than do light
   waves.
5. sound waves occur in air and light waves do not.

8
In the figure, a beam of light from an underwater
source is incident on a layer of carbon disulfide
and the glass bottom of the container. The
container is surrounded by air. Some of the
refracted and reflected rays are shown in the
diagram. For the rays shown, the interface at
which the reflected light changes phase is

1. 1 only
2. 2 only
3. 3 only
4. 1 and 2
5. 2 and 3

9
In the figure, a beam of light from an underwater
source is incident on a layer of carbon disulfide
and the glass bottom of the container. The
container is surrounded by air. Some of the
refracted and reflected rays are shown in the
diagram. For the rays shown, the interface at
which the reflected light changes phase is

1. 1 only
2. 2 only
3. 3 only
4. 1 and 2
5. 2 and 3

10
The two waves shown come from a source where they
were initially coherent. The path difference
could be

1. ? ?
2. ½ ?
3. ¼ ?
4. ?
5. It is not possible to answer this question
   without additional information.

11
The two waves shown come from a source where they
were initially coherent. The path difference
could be

1. ? ?
2. ½ ?
3. ¼ ?
4. ?
5. It is not possible to answer this question
   without additional information.

12
The phase difference for the two waves shown in
the figure is

1. 2p
2. p
3. 2p/3
4. p/2
5. It is not possible to answer this question
   without additional information.

13
The phase difference for the two waves shown in
the figure is

1. 2p
2. p
3. 2p/3
4. p/2
5. It is not possible to answer this question
   without additional information.

14
Which of the following statements is true?

1. When two harmonic waves of the same frequency and
   wavelength but differing in phase combine, the
   resultant wave is a harmonic wave whose amplitude
   depends on the phase difference.
2. A phase difference between two waves can be the
   result of a difference in path length.
3. A path difference of one wavelength is equivalent
   to no phase difference at all.
4. A phase difference between two waves can be the
   result of reflection from a boundary surface.
5. All of these are correct.

15
Which of the following statements is true?

1. When two harmonic waves of the same frequency and
   wavelength but differing in phase combine, the
   resultant wave is a harmonic wave whose amplitude
   depends on the phase difference.
2. A phase difference between two waves can be the
   result of a difference in path length.
3. A path difference of one wavelength is equivalent
   to no phase difference at all.
4. A phase difference between two waves can be the
   result of reflection from a boundary surface.
5. All of these are correct.

16
Chapter 33 Interferenceand Diffraction

• Section 33-2 Interference in Thin Films

17
For us to see interference phenomena in a thin
film,

1. the incoming light must be monochromatic.
2. the index of refraction of the thin film must be
   greater than the index of refraction of the
   material below it.
3. the index of refraction of the thin film must be
   less than the index of refraction of the material
   below it.
4. the incoming light must be multicolored.
5. None of these conditions need exist.

18
For us to see interference phenomena in a thin
film,

1. the incoming light must be monochromatic.
2. the index of refraction of the thin film must be
   greater than the index of refraction of the
   material below it.
3. the index of refraction of the thin film must be
   less than the index of refraction of the material
   below it.
4. the incoming light must be multicolored.
5. None of these conditions need exist.

19
Why are fringes not observed if the angle of the
wedge of air in the diagram is too large?

1. For a large angle, the small-angle approximation
   (sin ? ?) is not valid.
2. The light passing through the wedge of air loses
   its coherence.
3. The fringes overlap.
4. The fringes are too close together to be seen
   individually.
5. None of these is correct.

20
Why are fringes not observed if the angle of the
wedge of air in the diagram is too large?

1. For a large angle, the small-angle approximation
   (sin ? ?) is not valid.
2. The light passing through the wedge of air loses
   its coherence.
3. The fringes overlap.
4. The fringes are too close together to be seen
   individually.
5. None of these is correct.

21
For two identical rays of light to interfere
destructively, their path lengths

1. must be equal.
2. must differ by an odd number of half wavelengths.
   
3. must differ by an integral number of wavelengths.

22
For two identical rays of light to interfere
destructively, their path lengths

1. must be equal.
2. must differ by an odd number of half wavelengths.
   
3. must differ by an integral number of wavelengths.

23
The main effect contributing to the production of
different colors seen on a soap bubble is

1. the dispersion of light by the water in the soap.
2. the interference of light reflected from the
   front and back of the soap film.
3. the polarization of light by the soap film.
4. total internal reflection of light in the soap
   film.
5. None of the statements is correct.

24
The main effect contributing to the production of
different colors seen on a soap bubble is

1. the dispersion of light by the water in the soap.
2. the interference of light reflected from the
   front and back of the soap film.
3. the polarization of light by the soap film.
4. total internal reflection of light in the soap
   film.
5. None of the statements is correct.

25
A wedge-shaped film of air is formed by placing
two flat glass plates with one end touching each
other and the other end spaced by a gold leaf.
The wedge is then illuminated using a
monochromatic light of wavelength 590 nm from
above and the complete fringe pattern is shown.
The thickness of the gold leaf is approximately

1. 7.1 ?m
2. 7.4 ?m
3. 6.5 ?m
4. 6.8 ?m
5. 7.8 ?m

26
A wedge-shaped film of air is formed by placing
two flat glass plates with one end touching each
other and the other end spaced by a gold leaf.
The wedge is then illuminated using a
monochromatic light of wavelength 590 nm from
above and the complete fringe pattern is shown.
The thickness of the gold leaf is approximately

1. 7.1 ?m
2. 7.4 ?m
3. 6.5 ?m
4. 6.8 ?m
5. 7.8 ?m

27
A wedge-shaped film of air is formed by placing a
glass plate of unknown flatness upon second glass
plate that is known to be perfectly flat. The
wedge is then illuminated using a monochromatic
light from above and a fringe pattern is shown.
The wedge of air is thicker on the right than on
the left. From the fringe pattern one can
conclude that the bottom surface of the first
glass plate is

1. perfectly flat.
2. concave.
3. convex.
4. No conclusion can be drawn about the shape.

28
A wedge-shaped film of air is formed by placing a
glass plate of unknown flatness upon second glass
plate that is known to be perfectly flat. The
wedge is then illuminated using a monochromatic
light from above and a fringe pattern is shown.
The wedge of air is thicker on the right than on
the left. From the fringe pattern one can
conclude that the bottom surface of the first
glass plate is

1. perfectly flat.
2. concave.
3. convex.
4. No conclusion can be drawn about the shape.

29
The interference pattern is from a lens placed on
a flat reflecting surface illuminate using a
monochromatic light from above. From the pattern
one can conclude that the lens

1. is more curved on the left and right sides
   compared to top and bottom.
2. is more curved on the top and bottom compared to
   the left and right sides.
3. has a spherical surface.
4. has a concave surface.
5. None of the above statements is correct.

30
The interference pattern is from a lens placed on
a flat reflecting surface illuminate using a
monochromatic light from above. From the pattern
one can conclude that the lens

1. is more curved on the left and right sides
   compared to top and bottom.
2. is more curved on the top and bottom compared to
   the left and right sides.
3. has a spherical surface.
4. has a concave surface.
5. None of the above statements is correct.

31
Chapter 33 Interferenceand Diffraction

• Section 33-3 Two-Slit Interference Pattern and
  Concept Check 33-1

32
Two narrow slits are illuminated by monochromatic
light. If the distance between the slits is equal
to 2.75 wavelengths, what is the maximum number
of dark fringes that can be seen on a screen?

1. 2
2. 3
3. 4
4. 5
5. 6

33
Two narrow slits are illuminated by monochromatic
light. If the distance between the slits is equal
to 2.75 wavelengths, what is the maximum number
of dark fringes that can be seen on a screen?

1. 2
2. 3
3. 4
4. 5
5. 6

34
Which of the following statements about Young's
double-slit experiment is false?

1. The bands of light are caused by the interference
   of the light coming from the two slits.
2. The results of the double-slit experiment support
   the particle theory of light.
3. Double-slit interference patterns can also be
   produced with sound and water waves.
4. If the slits are moved closer together, the bands
   of light on the screen are spread farther apart.
5. The pattern of light on the screen consists of
   many bands, not just two bands.

35
Which of the following statements about Young's
double-slit experiment is false?

1. The bands of light are caused by the interference
   of the light coming from the two slits.
2. The results of the double-slit experiment support
   the particle theory of light.
3. Double-slit interference patterns can also be
   produced with sound and water waves.
4. If the slits are moved closer together, the bands
   of light on the screen are spread farther apart.
5. The pattern of light on the screen consists of
   many bands, not just two bands.

36
The distance between the slits in a double-slit
experiment is increased by a factor of 4. If the
distance between the fringes is small compared
with the distance from the slits to the screen,
the distance between adjacent fringes near the
center of the interference pattern

1. increases by a factor of 2.
2. increases by a factor of 4.
3. depends on the width of the slits.
4. decreases by a factor of 2.
5. decreases by a factor of 4.

37
The distance between the slits in a double-slit
experiment is increased by a factor of 4. If the
distance between the fringes is small compared
with the distance from the slits to the screen,
the distance between adjacent fringes near the
center of the interference pattern

1. increases by a factor of 2.
2. increases by a factor of 4.
3. depends on the width of the slits.
4. decreases by a factor of 2.
5. decreases by a factor of 4.

38
In a double-slit experiment, the distance from
the slits to the screen is decreased by a factor
of 2. If the distance between the fringes is
small compared with the distance from the slits
to the screen, the distance between adjacent
fringes

1. increases by a factor of 2.
2. increases by a factor of 4.
3. depends on the width of the slits.
4. decreases by a factor of 2.
5. decreases by a factor of 4.

39
In a double-slit experiment, the distance from
the slits to the screen is decreased by a factor
of 2. If the distance between the fringes is
small compared with the distance from the slits
to the screen, the distance between adjacent
fringes

1. increases by a factor of 2.
2. increases by a factor of 4.
3. depends on the width of the slits.
4. decreases by a factor of 2.
5. decreases by a factor of 4.

40
In order to produce several easily visible
interference fringes from two narrow slits using
light of a single wavelength, the distance
between the slits must be of the order

1. of a few tenths of the wavelength.
2. of a few wavelengths.
3. of a few tens wavelengths.
4. of a few hundreds wavelengths.
5. The distance does not matter.

41
In order to produce several easily visible
interference fringes from two narrow slits using
light of a single wavelength, the distance
between the slits must be of the order

1. of a few tenths of the wavelength.
2. of a few wavelengths.
3. of a few tens wavelengths.
4. of a few hundreds wavelengths.
5. The distance does not matter.

42
When the slits in Youngs experiment are moved
closer together, the fringes

1. remains unchanged.
2. move closer together.
3. move further apart.

43
When the slits in Youngs experiment are moved
closer together, the fringes

1. remains unchanged.
2. move closer together.
3. move further apart.

44
A narrow, horizontal slit is 0.50 mm above a
horizontal plane mirror. The slit is illuminated
by light of wavelength 400 nm. The interference
pattern is viewed on a screen 10.0 m from the
slit. What is the vertical distance from the
mirror to the first bright line?

1. 1.0 mm
2. 2.0 mm
3. 3.0 mm
4. 4.0 mm
5. 1.2 mm

45
A narrow, horizontal slit is 0.50 mm above a
horizontal plane mirror. The slit is illuminated
by light of wavelength 400 nm. The interference
pattern is viewed on a screen 10.0 m from the
slit. What is the vertical distance from the
mirror to the first bright line?

1. 1.0 mm
2. 2.0 mm
3. 3.0 mm
4. 4.0 mm
5. 1.2 mm

46
Chapter 33 Interferenceand Diffraction

• Section 33-4 Diffraction Pattern of a Single Slit

47
When a parallel beam of light is diffracted at a
single slit,

1. the narrower the slit, the narrower the central
   diffraction maximum.
2. the narrower the slit, the wider the central
   diffraction maximum.
3. the width of the central diffraction maximum is
   independent of the width of the slit.

48
When a parallel beam of light is diffracted at a
single slit,

1. the narrower the slit, the narrower the central
   diffraction maximum.
2. the narrower the slit, the wider the central
   diffraction maximum.
3. the width of the central diffraction maximum is
   independent of the width of the slit.

49
The graphs are plots of relative intensities of
various diffraction patterns versus the sine of
the angle from the central maximum. Which graph
represents the diffraction pattern from the
widest single slit?
50
The graphs are plots of relative intensities of
various diffraction patterns versus the sine of
the angle from the central maximum. Which graph
represents the diffraction pattern from the
widest single slit?
51
The bending of light around an obstacle such as
the edge of a slit is called

1. diffraction
2. dispersion
3. reflection
4. refraction
5. polarization

52
The bending of light around an obstacle such as
the edge of a slit is called

1. diffraction
2. dispersion
3. reflection
4. refraction
5. polarization

53
The diffraction pattern of a single slit is shown
in the figure. At which point is the path
difference of the extreme rays approximately two
wavelengths?
54
The diffraction pattern of a single slit is shown
in the figure. At which point is the path
difference of the extreme rays approximately two
wavelengths?
55
As the width of the slit producing a single-slit
diffraction pattern is slowly and steadily
reduced (always remaining larger than the
wavelength of the light), the diffraction pattern

1. slowly and steadily gets wider.
2. slowly and steadily gets brighter.
3. does not change because the wavelength of the
   light does not change.
4. slowly and steadily gets narrower.
5. None of these is correct.

56
As the width of the slit producing a single-slit
diffraction pattern is slowly and steadily
reduced (always remaining larger than the
wavelength of the light), the diffraction pattern

1. slowly and steadily gets wider.
2. slowly and steadily gets brighter.
3. does not change because the wavelength of the
   light does not change.
4. slowly and steadily gets narrower.
5. None of these is correct.

57
The pattern of light and dark fringes formed in
Young's double-slit experiment is due to

1. interference and dispersion.
2. diffraction and refraction.
3. refraction and interference.
4. refraction and dispersion.
5. interference and diffraction.

58
The pattern of light and dark fringes formed in
Young's double-slit experiment is due to

1. interference and dispersion.
2. diffraction and refraction.
3. refraction and interference.
4. refraction and dispersion.
5. interference and diffraction.

59
The interference and diffraction envelopes of a
double slit are shown separately but to the same
scale in the figure. For this arrangement, the
number of fringes in one of the second
diffraction maxima is

1. 3
2. 4
3. 5
4. 7
5. 0

60
The interference and diffraction envelopes of a
double slit are shown separately but to the same
scale in the figure. For this arrangement, the
number of fringes in one of the second
diffraction maxima is

1. 3
2. 4
3. 5
4. 7
5. 0

61
The fringes shown are the result of

1. a single slit.
2. a double slit.
3. three slits.
4. five slits.
5. many slits.

62
The fringes shown are the result of

1. a single slit.
2. a double slit.
3. three slits.
4. five slits.
5. many slits.

63
Chapter 33 Interferenceand Diffraction

• Section 33-5 Using Phasors to Add Harmonic Waves

64
Which of the phasor diagrams shows the first
minimum for five equally spaced in-phase sources?
65
Which of the phasor diagrams shows the first
minimum for five equally spaced in-phase sources?
66
Five coherent sources are used to produce an
interference pattern. The phasor diagram shown
could be used to calculate the intensity of the

1. first minimum in the interference pattern.
2. second maximum in an interference pattern.
3. first maximum in an interference pattern.
4. second minimum in an interference pattern.
5. None of these is correct.

67
Five coherent sources are used to produce an
interference pattern. The phasor diagram shown
could be used to calculate the intensity of the

1. first minimum in the interference pattern.
2. second maximum in an interference pattern.
3. first maximum in an interference pattern.
4. second minimum in an interference pattern.
5. None of these is correct.

68
Chapter 33 Interferenceand Diffraction

• Section 33-6 Fraunhofer and Fresnel Diffraction

69
In demonstrating single-slit Fraunhofer
diffraction, decreasing the wavelength of the
light while keeping the slit width constant

1. does not affect the width of the central maximum.
   
2. increases the number of fringes within the
   central maximum.
3. decreases the number of fringes within the
   central maximum.
4. increases the width of the central maximum.
5. decreases the width of the central maximum

70
In demonstrating single-slit Fraunhofer
diffraction, decreasing the wavelength of the
light while keeping the slit width constant

1. does not affect the width of the central maximum.
   
2. increases the number of fringes within the
   central maximum.
3. decreases the number of fringes within the
   central maximum.
4. increases the width of the central maximum.
5. decreases the width of the central maximum

71
Chapter 33 Interferenceand Diffraction

• Section 33-7 Diffraction and Resolution and
  Concept Check 33-2

72
True or False Fraunhofer diffraction is a
limiting case of Fresnel diffraction.

1. True
2. False

73
True or False Fraunhofer diffraction is a
limiting case of Fresnel diffraction.

1. True
2. False

74
Rayleigh's criterion is most closely associated
with

1. diffraction
2. coherence
3. dispersion
4. polarization
5. reflection

75
Rayleigh's criterion is most closely associated
with

1. diffraction
2. coherence
3. dispersion
4. polarization
5. reflection

76
The pupil of the human eye has a diameter of
about 5 mm. When the wavelength of light
incident on the pupil is 500 nm, the smallest
angular separation of two resolvable sources is
approximately

1. 1"
2. 1'
3. 1º
4. 10º
5. 1 radian

77
The pupil of the human eye has a diameter of
about 5 mm. When the wavelength of light
incident on the pupil is 500 nm, the smallest
angular separation of two resolvable sources is
approximately

1. 1"
2. 1'
3. 1º
4. 10º
5. 1 radian

78
The white circles in the figure represent minima
of the diffraction pattern formed when a bright
point-source object is viewed through a small
circular opening. In accordance with Rayleigh's
criterion, the closest central maximum of another
point source that could lie in this pattern and
still be barely resolvable

1. would be at point A.
2. would be at point B.
3. would be at point C.
4. would be at point D.
5. must lie outside all discernible diffraction
   rings.

79
The white circles in the figure represent minima
of the diffraction pattern formed when a bright
point-source object is viewed through a small
circular opening. In accordance with Rayleigh's
criterion, the closest central maximum of another
point source that could lie in this pattern and
still be barely resolvable

1. would be at point A.
2. would be at point B.
3. would be at point C.
4. would be at point D.
5. must lie outside all discernible diffraction
   rings.

80
The diffraction image of the point object O is
indicated in the figure. Of the point objects A,
B, C, D, and E, which is the one closest to O and
whose diffraction image could just be resolved
from that of O according to the Rayleigh
criterion?
81
The diffraction image of the point object O is
indicated in the figure. Of the point objects A,
B, C, D, and E, which is the one closest to O and
whose diffraction image could just be resolved
from that of O according to the Rayleigh
criterion?
82
Diffraction occurs when light passes

1. by a small particle.
2. through a small hole.
3. through a double slit.
4. by a sharp edge.
5. Diffraction occurs in all of these conditions.

83
Diffraction occurs when light passes

1. by a small particle.
2. through a small hole.
3. through a double slit.
4. by a sharp edge.
5. Diffraction occurs in all of these conditions.

84
The size of the smallest things that can be seen
with an optical microscope is limited by
diffraction. Which of the following could help a
microscopist see smaller things?

1. A more powerful microscope could be used.
2. The microscope could have a lens with a shorter
   focal length.
3. The microscope could have a lens with a longer
   focal length.
4. The diameter of the lens could be smaller.
5. Light with a shorter wavelength could be used.

85
The size of the smallest things that can be seen
with an optical microscope is limited by
diffraction. Which of the following could help a
microscopist see smaller things?

1. A more powerful microscope could be used.
2. The microscope could have a lens with a shorter
   focal length.
3. The microscope could have a lens with a longer
   focal length.
4. The diameter of the lens could be smaller.
5. Light with a shorter wavelength could be used.

86
An antenna for receiving television signals from
a satellite has a diameter of 3 m. The signals
have a wavelength of 24 cm. If the diameter of
the antenna is reduced to 50 cm, for what signal
wavelengths does the antenna still have the same
angular resolution?

1. 4.0 cm
2. 6.0 cm
3. 8.0 cm
4. 1.4 m
5. 24 cm

87
An antenna for receiving television signals from
a satellite has a diameter of 3 m. The signals
have a wavelength of 24 cm. If the diameter of
the antenna is reduced to 50 cm, for what signal
wavelengths does the antenna still have the same
angular resolution?

1. 4.0 cm
2. 6.0 cm
3. 8.0 cm
4. 1.4 m
5. 24 cm

88
In accordance with the Rayleigh criterion, two
points can be just resolved if the centers of
their diffraction patterns are separated by

1. one wavelength.
2. twice the width of either central maximum.
3. one-half the width of either central maximum.
4. the width of the aperture.
5. the reciprocal of one wavelength.

89
In accordance with the Rayleigh criterion, two
points can be just resolved if the centers of
their diffraction patterns are separated by

1. one wavelength.
2. twice the width of either central maximum.
3. one-half the width of either central maximum.
4. the width of the aperture.
5. the reciprocal of one wavelength.

90
Chapter 33 Interferenceand Diffraction

• Section 33-8 Diffraction Gratings

91
The type of electromagnetic radiation that is
employed when crystals are used as diffraction
gratings is

1. infrared
2. X-rays
3. visible
4. ultraviolet
5. microwaves

92
The type of electromagnetic radiation that is
employed when crystals are used as diffraction
gratings is

1. infrared
2. X-rays
3. visible
4. ultraviolet
5. microwaves

93
Monochromatic light of wavelength l is normally
incident on a plane diffraction grating, and
three rays of light (A, B, and C) are observed.
Of these three rays

1. A is the first order, B is the second order, and
   C is the third order.
2. B is the first order, and A and C are the second
   order.
3. A is the zero order, B is the first order, and C
   is the second order.
4. B is the zero order, and A and C are the first
   order.
5. A, B, and C are all the first order.

94
Monochromatic light of wavelength l is normally
incident on a plane diffraction grating, and
three rays of light (A, B, and C) are observed.
Of these three rays

1. A is the first order, B is the second order, and
   C is the third order.
2. B is the first order, and A and C are the second
   order.
3. A is the zero order, B is the first order, and C
   is the second order.
4. B is the zero order, and A and C are the first
   order.
5. A, B, and C are all the first order.

95
A student looks through a transmission grating at
the light from a helium light source. He sees the
red, yellow, and green light from the source
superimposed on a meterstick. If the yellow lines
are the ones indicated in the figure, then

1. 1 and 2 are green 3 and 4 are red.
2. 1 and 4 are red 2 and 3 are green.
3. 1 and 4 are green 2 and 3 are red.
4. 1 and 3 are red 2 and 4 are green.
5. 1 and 3 are green 2 and 4 are red.

96
A student looks through a transmission grating at
the light from a helium light source. He sees the
red, yellow, and green light from the source
superimposed on a meterstick. If the yellow lines
are the ones indicated in the figure, then

1. 1 and 2 are green 3 and 4 are red.
2. 1 and 4 are red 2 and 3 are green.
3. 1 and 4 are green 2 and 3 are red.
4. 1 and 3 are red 2 and 4 are green.
5. 1 and 3 are green 2 and 4 are red.

97
If the prism spectrum of a source is a line
spectrum, the grating spectrum would

1. be an absorption spectrum.
2. also be a line spectrum.
3. be a continuous spectrum.

98
If the prism spectrum of a source is a line
spectrum, the grating spectrum would

1. be an absorption spectrum.
2. also be a line spectrum.
3. be a continuous spectrum.

99
White light is in one case dispersed by
refraction on passing through a glass prism and
in a second case diffracted by means of a
grating. When the red component and the blue
component are considered, it is found that

1. red is both refracted and diffracted at greater
   angles than blue.
2. blue is both refracted and diffracted at greater
   angles than red.
3. red is refracted at a greater angle than blue,
   but blue is diffracted at a greater angle than
   red.
4. blue is refracted at a greater angle than red,
   but red is diffracted at a greater angle than
   blue.
5. both red and blue are refracted at the same angle
   and diffracted at the same angle.

100
White light is in one case dispersed by
refraction on passing through a glass prism and
in a second case diffracted by means of a
grating. When the red component and the blue
component are considered, it is found that

1. red is both refracted and diffracted at greater
   angles than blue.
2. blue is both refracted and diffracted at greater
   angles than red.
3. red is refracted at a greater angle than blue,
   but blue is diffracted at a greater angle than
   red.
4. blue is refracted at a greater angle than red,
   but red is diffracted at a greater angle than
   blue.
5. both red and blue are refracted at the same angle
   and diffracted at the same angle.

101
Which of two diffraction gratings, one with N1
slits per centimeter and the other with N2 slits
per centimeter, has the greater resolving power
if N1 is greater than N2?

1. the grating with N1 slits per centimeter
2. the grating with N2 slits per centimeter
3. They both have the same resolving power, but the
   one with N1 slits per centimeter has sharper
   spectral lines.
4. They both have the same resolving power, but the
   one with N2 slits per centimeter has sharper
   spectral lines.
5. The width of the individual slits must be known
   to answer this question.

102
Which of two diffraction gratings, one with N1
slits per centimeter and the other with N2 slits
per centimeter, has the greater resolving power
if N1 is greater than N2?

1. the grating with N1 slits per centimeter
2. the grating with N2 slits per centimeter
3. They both have the same resolving power, but the
   one with N1 slits per centimeter has sharper
   spectral lines.
4. They both have the same resolving power, but the
   one with N2 slits per centimeter has sharper
   spectral lines.
5. The width of the individual slits must be known
   to answer this question.

103
The spacing between the adjacent lines of a
diffraction grating is the same as the distance
between the two slits in the Youngs double slit
experiment. Both are illuminated by light of the
same wavelength. In which way do the interference
fringes seen on the screen differ for the two
methods?

1. There is no difference in the interference
   fringes.
2. The fringes from the grating are farther apart.
3. The fringes from the double slit are farther
   apart.
4. Each of the fringes from the grating is narrower
   than the double slit.
5. Each of the fringes from the double slit is
   narrower than the grating.

104
The spacing between the adjacent lines of a
diffraction grating is the same as the distance
between the two slits in the Youngs double slit
experiment. Both are illuminated by light of the
same wavelength. In which way do the interference
fringes seen on the screen differ for the two
methods?

1. There is no difference in the interference
   fringes.
2. The fringes from the grating are farther apart.
3. The fringes from the double slit are farther
   apart.
4. Each of the fringes from the grating is narrower
   than the double slit.
5. Each of the fringes from the double slit is
   narrower than the grating.