Deck 34: The Wave Nature of Light; Interference

Question 1

Interference of light is evidence supporting

A)the wave theory of light.
B)the wave theory except in the case of constructive interference.
C)both the particle and wave theories of light.
D)the particle theory of light.
E)the wave theory except in the case of destructive interference.

Answer 1

the wave theory of light.

Question 2

According to Huygens' principle, each point on a wave can be considered as the source of a new wave that propagates from that point onward.

Answer 2

True

Question 3

State Huygen's principle.

Answer 3

Every point on a wave front can be considered as a source of tiny wavelets that spread out in the forward direction at the speed of the wave itself. The new wave front is the envelope of all the wavelets - that is, tangent to all of them.

Question 4

In the two-slit experiment, for the condition of bright fringes, the value of m = +2 corresponds to a path difference of λ.

Question 5

Radio waves are diffracted by large objects such as buildings, whereas light is not noticeably diffracted. Why is this?

A)Radio waves are unpolarized, whereas light is plane polarized.
B)The wavelength of light is much smaller than the wavelength of radio waves.
C)The wavelength of light is much greater than the wavelength of radio waves.
D)Radio waves are coherent and light is usually not coherent.
E)Light is coherent and radio waves are usually not coherent.

Question 6

Huygen's principle indicates

A)each point on a wavefront is a source of wavelets.
B)materials are isotropic.
C)light travels with speed c.
D)all of the above.
E)none of the above.

Question 7

When a light wave enters into a medium of different optical density,

A)only its speed changes.
B)its speed and frequency change.
C)its speed and wavelength change.
D)its frequency and wavelength change.
E)its speed, frequency, and wavelength change.

Question 8

What principle is responsible for alternating light and dark bands when light passes through two or more narrow slits?

A)reflection
B)refraction
C)polarization
D)dispersion
E)interference

Question 9

The interference pattern observed in Newton's rings experiment is because of the path difference between the top surface and the bottom surface of the air between the pieces of glass.

Question 10

In Young's double-slit experiment, light coming from each slit arrives in phase at the first maximum on either side of the central bright fringe.

Question 11

What principle is responsible for light spreading as it passes through a narrow slit?

A)reflection
B)refraction
C)polarization
D)diffraction
E)interference

Question 12

The wavelength of light is important for thin film interference to occur within the film itself.

Question 13

When light travels from a larger index of refraction towards a smaller index of refraction, there is no phase change upon reflection at the boundary.

Question 14

A wave that travels from a medium of lower index of refraction to a medium of higher index of refraction undergoes 180° phase changes relative to the incident wave.

Question 15

In the two-slit experiment, for the condition of dark fringes, the value of m = +2 corresponds to a path difference of 3λ/2.

Question 16

In the two-slit experiment, for the condition of dark fringes, the value of m = +1 corresponds to a path difference of 3λ/2.

Question 17

In the experiment for interference using the concept of air wedge, the point where the glass plates touch in an air wedge is a dark fringe.

Question 18

A wave front is not a surface of constant phase within a wave.

Question 19

If two or more sources of light are to show interference patterns, they must be coherent.

Question 20

For two beams of light traveling different distances in reaching a point, and to form maximum constructive interference at that point, the beams must travel paths that differ by a whole number of wavelengths.

Question 21

The maximum intensity using coherent sources compared to the maximum intensity using random sources for sources of equal strength is that the maximum in the coherent case is

A)0.707 times the incoherent.
B)triple the incoherent.
C)the same as the incoherent.
D)half the incoherent.
E)double the incoherent.

Question 22

Which one of the following experiments is the justification for the wave theory of light?

A)Frank-Hertz experiment
B)Newton's rings experiment
C)Huygens' experiment
D)Young's double slit experiment
E)none of the above

Question 23

At the second maxima on either side of the central bright spot in a double-slit experiment, light from

A)each opening travels the same distance.
B)one opening travels twice as far as light from the other opening.
C)one opening travels one wavelength of light farther than light from the other opening.
D)one opening travels two wavelengths of light farther than light from the other opening.
E)one opening travels four wavelength of light farther than light from the other opening.

Question 24

Two light sources are said to be coherent if they

A)are of the same frequency.
B)are of the same amplitude.
C)are of the same frequency, and maintain a constant phase difference.
D)are of the same amplitude, and maintain a constant phase difference.
E)are of the same frequency and amplitude.

Question 25

Sources are coherent if

A)the distance to them is the same.
B)they do not come from lasers.
C)they have a zero phase difference.
D)they have a constant phase difference.
E)they only come from lasers.

Question 26

If in a double-slit experiment the wavelength of light is increased, which of the following happens to the interference pattern shown on the screen?

A)The maxima get further apart.
B)The maxima stay at the same position.
C)The minima and maxima stay at the same position.
D)The minima get closer together.
E)The minima stay at the same position.

Question 27

When a beam of light, which is traveling in glass, strikes an air boundary, there is

A)a 90° phase change in the reflected beam.
B)no phase change in the reflected beam.
C)a 180° phase change in the reflected beam.
D)a 60° phase change in the reflected beam.
E)a 45° phase change in the reflected beam.

Question 28

If a wave from one slit of a Young's double slit experiment arrives at a point on the screen one-half wavelength behind the wave from the other slit, which is observed at that point?

A)bright fringe
B)dark fringe
C)gray fringe
D)multi-colored fringe

Question 29

At the first minima on either side of the central bright spot in a double-slit experiment, light from each opening arrives

A)in phase.
B)45° out of phase.
C)90° out of phase.
D)180° out of phase.
E)none of the given answers

Question 30

One beam of coherent light travels path P₁ in arriving at point Q and another coherent beam travels path P₂ in arriving at the same point. If these two beams are to interfere destructively, the path difference P₁ - P₂ must be equal to

A)an odd number of half-wavelengths.
B)an even number of half-wavelengths.
C)zero.
D)a whole number of wavelengths.
E)a whole number of half-wavelengths.

Question 31

The colors on an oil slick are caused by reflection and

A)diffraction.
B)interference.
C)refraction.
D)polarization.

Question 32

When light in medium 1 is reflected from the surface of medium 2 with the indices of refraction of the media being n₁ and n₂ respectively, the reflected light has a phase difference of 180° if

A)n₁ > 3 n₂.
B)n₁ = n₂.
C)n₁ < n₂.
D)n₁ > n₂.
E)n₁ > 2 n₂.

Question 33

At the first maxima on either side of the central bright spot in a double-slit experiment, light from each opening arrives

A)in phase.
B)45° out of phase.
C)90° out of phase.
D)180° out of phase.
E)none of the given answers

Question 34

When a beam of light, which is traveling in air, is reflected by a glass surface, there is

A)a 90° phase change in the reflected beam.
B)no phase change in the reflected beam.
C)a 180° phase change in the reflected beam.
D)a 60° phase change in the reflected beam.
E)a 45° phase change in the reflected beam.

Question 35

Waves that are emitted in phase from two sources will undergo destructive interference when the paths from the sources differ by

A)an odd half-integer number of wavelengths.
B)a whole integer number of wavelengths.
C)an odd one-third-integer number of wavelengths.
D)any quarter-integer number of wavelengths.
E)none of the above.

Question 36

Waves that are emitted in phase from two sources will undergo constructive interference when the paths from the sources differ by

A)an odd half-integer number of wavelengths.
B)a whole integer number of wavelengths.
C)an odd one-third-integer number of wavelengths.
D)any quarter-integer number of wavelengths.
E)none of the above.

Question 37

Two beams of coherent light travel different paths arriving at point P. If the maximum destructive interference is to occur at point P, what should be the phase difference between the two waves?

A)The phase difference between the two waves is π/4.
B)The phase difference between the two waves is π/2.
C)The phase difference between the two waves is π.
D)The phase difference between the two waves is 2π.
E)The two waves are in phase.

Question 38

If in a double-slit experiment the slit separation is increased, which of the following happens to the interference pattern shown on the screen?

A)The minima get closer together.
B)The maxima stay at the same position.
C)The minima and maxima stay at the same position.
D)The minima stay at the same position.
E)The maxima get further apart.

Question 39

If in a double-slit experiment the distance to the screen is increased, which of the following happens to the interference pattern shown on the screen?

A)The minima get closer together.
B)The maxima stay at the same position.
C)The minima and maxima stay at the same position.
D)The maxima get further apart.
E)The minima stay at the same position.

Question 40

Two beams of coherent light travel different paths arriving at point P. If the maximum constructive interference is to occur at point P, what should be the phase difference between the two waves?

A)The phase difference between the two waves is π/4.
B)The phase difference between the two waves is π/2.
C)The phase difference between the two waves is π.
D)The phase difference between the two waves is 2π.
E)The phase difference between the two waves is 5π/2.

Question 41

In a Newton's rings apparatus, the interference effect observed between the rays occurs because of the path difference between

A)the top and bottom surfaces of the top piece of glass.
B)the top and bottom surfaces of the bottom piece of glass.
C)the top and bottom surfaces of the air between the pieces of glass.
D)the top and bottom surfaces of the oil between the pieces of glass.
E)the top surfaces between the top and bottom pieces of glass.

Question 42

Light has a wavelength of 600 nm in a vacuum. It passes into glass, which has an index of refraction of 1.50. What is the wavelength of the light in the glass?

A)600 nm
B)500 nm
C)400 nm
D)300 nm
E)200 nm

Question 43

In a Young's double slit experiment, the slit separation is made to be exactly 4λ. At what angle will the third bright fringe to the side of the central fringe occur? Caution: the angles involved are such that the approximation sinθ ≈ θ is not valid.

A)48.6°
B)75.0°
C)67.5°
D)36.9°
E)43.0°

Question 44

In the two-slit experiment, monochromatic light of wavelength 600 nm passes through a pair of slits separated by 2.20 x 10^-5 m.
(a) What is the angle corresponding to the first bright fringe?
(b) What is the angle corresponding to the second dark fringe?

Question 45

In a Young's double slit experiment, what is the ratio of the intensity at a point where the electric fields are out of phase by 30° to the central intensity.

A)0.93
B)1.9
C)2.1
D)0.47
E)0.75

Question 46

In the two-slit experiment, the distance between the slits and the screen is 1.1 m and the distance between the slits is 0.040 mm. If the first-order bright fringe is measured to be 3.4 cm from the centerline, what is the distance between the adjacent bright fringes?

A)1.7 cm
B)5.1 cm
C)7.0 cm
D)6.8 cm
E)3.4 cm

Question 47

In a Young's double slit experiment, if the separation between the two slits is 0.050 mm and the distance from the slits to a screen is 2.5 m, find the spacing between the first-order and second-order bright fringes for light with wavelength of 600 nm.

A)1.5 cm
B)3.0 cm
C)4.5 cm
D)6.0 cm
E)9.0 cm

Question 48

A monochromatic light is incident on a Young's double slit setup that has a slit separation of 30.0 μm. The resultant bright fringe separation is 2.15 cm on a screen 1.20 m from the double slit. What is the separation between the third-order bright fringe and the zeroth-order bright fringe?

A)8.60 cm
B)7.35 cm
C)6.45 cm
D)4.30 cm
E)2.70 cm

Question 49

Light from a monochromatic source shines through a double slit onto a screen 5.0 m away. The slits are 0.18 mm apart. The dark bands on the screen are measured to be 1.7 cm apart. What is the wavelength of the incident light?

A)457 nm
B)306 nm
C)392 nm
D)612 nm
E)784 nm

Question 50

Light from a 600 nm source goes through two slits 0.080 mm apart. What is the angular separation of the two first order maxima occurring on a screen 2.0 m from the slits?

A)0.15°
B)0.86°
C)0.015°
D)0.0075°
E)1.75°

Question 51

In a double-slit experiment, the slit separation is 2.0 mm, and two wavelengths, 750 nm and 900 nm, illuminate the slits. A screen is placed 2.0 m from the slits. At what distance from the central maximum on the screen will a bright fringe from one pattern first coincide with a bright fringe from the other?

A)1.5 mm
B)3.0 mm
C)4.5 mm
D)6.0 mm
E)9.0 cm

Question 52

Light of wavelength 575 nm falls on a double-slit and the third order bright fringe is seen at an angle of 6.5°. What is the separation between the double slits?

A)5.0 μm
B)10 μm
C)15 μm
D)20 μm
E)25 μm

Question 53

In a two-slit experiment, the third bright fringe away from the central fringe is observed at an angle of 7.0°. If the wavelength of the light is 490 nm, what is the distance between the two slits?

A)3.6 × 10^-5 m
B)4.0 × 10^-6 m
C)2.1 × 10^-6 m
D)2.1 × 10^-5 m
E)1.2 × 10^-5 m

Question 54

What is the phase difference in a Young's double slit experiment where the intensity is half that of the central maximum?

A)45°
B)180°
C)90°
D)23°
E)245°

Question 55

Light of wavelength 550 nm in air is found to travel at 1.96 × 10⁸ m/s in a certain liquid. Determine the wavelength of the light in the liquid.

A)550 nm
B)442 nm
C)359 nm
D)281 nm
E)303 nm

Question 56

Two light sources individually provide intensity I_o at a point. If the sources are operated at the same time and are coherent but out of phase 30°, what is the intensity at that point?

A)3.7 I_o
B)2.0 I_o
C)3.0 I_o
D)2.8 I_o
E)1.0 I_o

Question 57

A soap bubble has an index of refraction of 1.33. What minimum thickness of this bubble will ensure maximum reflectance of normally incident 530 nm wavelength light?

A)24.9 nm
B)56.7 nm
C)99.6 nm
D)199 nm
E)398 nm

Question 58

In a double-slit experiment, the intensity of light at the center of the central fringe is measured to be 6.2 × 10^-6 W/ m². What is the intensity halfway between the center of the fringe and the first dark band?

A)6.2 × 10^-6 W/ m²
B)3.1 × 10^-6 W/ m²
C)4.7 × 10^-6 W/ m²
D)1.6 × 10^-6 W/ m²
E)0.12 × 10^-6 W/ m²

Question 59

A beam splitter in a Michelson interferometer is

A)an extremely sharp knife edge.
B)two transparent pipes.
C)a half-silvered mirror.
D)made of two mirrors.
E)made of three mirrors.

Question 60

In a two-slit experiment, the slit separation is 3.00 × 10^-5 m. The interference pattern is created on a screen that is 2.00 m away from the slits. If the seventh bright fringe on the screen is a linear distance of 10.0 cm away from the central fringe, what is the wavelength of the light?

A)100 nm
B)204 nm
C)214 nm
D)224 nm
E)234 nm

Question 61

A thin layer of oil (n = 1.25) is on top of a puddle of water (n = 1.33). If normally incident 500 nm light is strongly reflected, what is the minimum thickness of the oil layer?

A)200 nm
B)250 nm
C)100 nm
D)400 nm
E)150 nm

Question 62

Two pieces of optically flat glass (n = 1.50) touch at one edge and a separated by a thin stretched fiber at the opposite edge. Light of wavelength 500 nm is shone from above and 100 dark fringes are counted. How thick is the fiber?

A)13 μm
B)100 μm
C)5 μm
D)50 μm
E)25 μm

Question 63

A puddle of water has a thin film of gasoline floating on it. A beam of light is shining perpendicular on the film. If the wavelength of light incident on the film is 560 nm and the indices of refraction of gasoline and water are 1.40 and 1.33, respectively, what is the minimum thickness of the film to see a bright reflection?

A)100 nm
B)200 nm
C)300 nm
D)400 nm
E)500 nm

Question 64

White light incident normal to a thin soap film with n = 1.34 reflects with an interference maximum at 684 nm and an interference minimum at 570 nm with no minima between those two values. What is the thickness of the soap film?

A)766 nm
B)627 nm
C)638 nm
D)894 nm
E)510 nm

Question 65

A coating is being applied to reduce the reflectivity of a pane of glass to light with a wavelength of 522 nm incident near the normal to the pane. If the material has an index of refraction of 1.375, how thick should the coating be?

A)60 nm
B)95 nm
C)145 nm
D)65 nm
E)80 nm

Question 66

Light of wavelength 500 nm is incident on a thin sheet of plastic film (n= 1.50) in air. What is the thinnest the sheet can be so that the reflected light from the surfaces undergoes constructive interference?

A)50 nm
B)250 nm
C)333 nm
D)167 nm
E)83 nm

Question 67

Light of wavelength 500 nm illuminates a soap film ( n = 1.33). What is the minimum thickness of film that will give an interference maximum when the light is incident normally on it?

A)24 nm
B)94 nm
C)188 nm
D)279 nm
E)376 nm

Question 68

Light of wavelength 500 nm is incident on a thin sheet of plastic film (n= 1.50) in air. What is the thinnest the sheet can be so that the reflected light from the surfaces undergoes destructive interference?

A)50 nm
B)250 nm
C)83 nm
D)333 nm
E)167 nm

Question 69

Two flat glass plates, 10.0 cm wide, touch at one end but are separated by a thin wire at the other end, forming a wedge. Light with a wavelength of 450 nm shines almost perpendicularly on the glass and forms fringes which are 1.80 mm apart. What is the diameter of the wire?

A)25.0 μm
B)17.5 μm
C)20.0 μm
D)12.5 μm
E)10.0 μm

Question 70

A very fine thread is placed between two glass plates on one side and the other side is touching to form a wedge. A beam of monochromatic light of wavelength 600 nm illuminates the wedge and 178 bright fringes are observed. What is the thickness of the thread?

A)22.3 μm
B)26.7 μm
C)32.3 μm
D)53.3 μm
E)76.3 μm

Question 71

If the movable mirror in a Michelson interferometer is moved 120 microns, how many fringes would be counted for 600 nm light?

A)200
B)720
C)100
D)300
E)400

Question 72

A soap bubble film (n=1.42) of thickness 106 nm results in a constructive interference in the reflected light if this film is illuminated by a beam of light with a wavelength of 601 nm. What are the next three thicknesses of this film that will also result in a constructive interference?

A)212 nm, 318 nm, 424 nm
B)53.0 nm, 35.3 nm, 26.5 nm
C)212 nm, 424 nm, 636 nm
D)67.0 nm, 42.4 nm, 22.3 nm
E)318 nm, 530 nm, 742 nm

Question 73

What is the minimum thickness of a nonreflecting film coating (n = 1.30) on a glass lens (n = 1.50) for wavelength 500 nm?

A)250 nm
B)192 nm
C)167 nm
D)96.2 nm
E)83.6 nm

Question 74

A piece of glass has a thin film of gasoline floating on it. A beam of light is shining perpendicular on the film. If the wavelength of light incident on the film is 560 nm and the indices of refraction of gasoline and glass are 1.40 and 1.50, respectively, what is the minimum thickness of the film to see a bright reflection?

A)500 nm
B)400 nm
C)300 nm
D)200 nm
E)100 nm

Question 75

Light with λ = 420 nm in incident normally onto the flat side of a plano-convex lens which is resting on a glass plate parallel to the flat side of the lens and forms a pattern of concentric luminous and dark rings (Newton's rings). The radius of the second dark ring is 2.0 mm. What is the radius of curvature of the curved side of the lens?

A)9.6 m
B)2.4 m
C)4.8 m
D)7.2 m
E)1.2 m

Question 76

Light with λ = 590 nm enters a Michelson interferometer. How many fringes traverse the field of view if the mirror of one arm of the interferometer is moved 0.44 mm?

A)1066
B)1812
C)2004
D)1776
E)1492

Question 77

How far would the movable mirror in a Michelson interferometer need to be moved for 800 fringes to be counted using 633 nm light?

A)0.253 mm
B)0.506 mm
C)1.11 mm
D)0.760 mm
E)2.23 mm