Question 1

In a Michelson interferometer, in order to shift the pattern by half a fringe, one of the mirrors at the end of an arm must be moved by:

Accepted Answer

A) one wavelength 
B) half a wavelength 
C) one-quarter wavelength 
D) It depends on the wavelength. 
E) It depends on which mirror is moved. 
A) one wavelength 
B) half a wavelength 
C) one-quarter wavelength 
D) It depends on the wavelength. 
E) It depends on which mirror is moved.

Question 2

To obtain an observable double-slit fringe pattern:

Accepted Answer

A) the light must be incident normally on the slits 
B) the light must be monochromatic 
C) the light must consist of plane waves 
D) the light must be coherent 
E) the screen must be far away from the slits 
A) the light must be incident normally on the slits 
B) the light must be monochromatic 
C) the light must consist of plane waves 
D) the light must be coherent 
E) the screen must be far away from the slits

Question 3

In a Young's double-slit experiment, the separation between slits is d and the screen is a distance D from the slits.D is much greater than d and $\lambda$is the wavelength of the light.The number of bright fringes per unit length on the screen is:

Accepted Answer

A) "Dd/$\lambda$" 
B) "D$\lambda$/d" 
C) "D/d$\lambda$" 
D) "$\lambda$/Dd" 
E) "d/D$\lambda$" 
A) "Dd/$\lambda$" 
B) "D$\lambda$/d" 
C) "D/d$\lambda$" 
D) "$\lambda$/Dd" 
E) "d/D$\lambda$"

Question 4

A thin film with an index of refraction of 1.60 is placed in one of the beams of a Michelson interferometer.If this causes a shift of 8 bright fringes in the pattern produced by light of wavelength 580 nm, what is the thickness of the film?

Accepted Answer

A) 1.5 µm 
B) 2.9 µm 
C) 3.9 µm 
D) 7.7 µm 
E) 16 µm 
A) 1.5 µm 
B) 2.9 µm 
C) 3.9 µm 
D) 7.7 µm 
E) 16 µm

Question 5

The reason there are two slits, rather than one, in a Young's experiment is:

Accepted Answer

A) to increase the intensity 
B) one slit is for frequency, the other for wavelength 
C) to create a path length difference 
D) one slit is for fields, the other is for fields 
E) two slits in parallel offer less resistance 
A) to increase the intensity 
B) one slit is for frequency, the other for wavelength 
C) to create a path length difference 
D) one slit is for fields, the other is for fields 
E) two slits in parallel offer less resistance

Question 6

The phase difference between the two waves which give rise to a dark spot in a Young's double-slit experiment is (where m = integer):

Accepted Answer

A) 2 $\pi$m 
B) 2 $\pi$m +  $\pi$/8 
C) 2 $\pi$m +  $\pi$/4 
D) 2 $\pi$m +  $\pi$/2 
E) 2 $\pi$m +  $\pi$ 
A) 2 $\pi$m 
B) 2 $\pi$m +  $\pi$/8 
C) 2 $\pi$m +  $\pi$/4 
D) 2 $\pi$m +  $\pi$/2 
E) 2 $\pi$m +  $\pi$

Question 7

In a Young's experiment, it is essential that the two beams:

Accepted Answer

A) have exactly equal intensity 
B) be exactly parallel 
C) travel equal distances 
D) come originally from the same source 
E) be composed of a broad band of frequencies 
A) have exactly equal intensity 
B) be exactly parallel 
C) travel equal distances 
D) come originally from the same source 
E) be composed of a broad band of frequencies

Question 8

The three factors that determine the interference of reflected waves from a thin film are:

Accepted Answer

A) incoming wavelength, speed of light in vacuum, thickness of the film 
B) shifts in wavelength on reflection, path length difference, index of refraction of the film 
C) incoming wavelength, index of refraction of the external medium, index of refraction of the film 
D) shifts in wavelength on reflection, index of refraction of the film, speed of light in vacuum 
E) path length difference, thickness of the film, index of refraction of the film 
A) incoming wavelength, speed of light in vacuum, thickness of the film 
B) shifts in wavelength on reflection, path length difference, index of refraction of the film 
C) incoming wavelength, index of refraction of the external medium, index of refraction of the film 
D) shifts in wavelength on reflection, index of refraction of the film, speed of light in vacuum 
E) path length difference, thickness of the film, index of refraction of the film

Question 9

Three experiments involving a thin film (in air)are shown.If t denotes the film thickness and $\lambda$ denotes the wavelength of the light in the film, which experiments will produce constructive interference as seen by the observer?

Accepted Answer

A) I only 
B) II only 
C) III only 
D) I and III only 
E) II and III only 
A) I only 
B) II only 
C) III only 
D) I and III only 
E) II and III only

Question 10

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 so that the center is now occupied by what was the 30th dark band.The wavelength of the light in this experiment is 480 nm and the index of the mica is 1.60.The mica thickness is:

Accepted Answer

A) 0.009 mm 
B) 0.012 mm 
C) 0.014 mm 
D) 0.024 mm 
E) 0.062 mm 
A) 0.009 mm 
B) 0.012 mm 
C) 0.014 mm 
D) 0.024 mm 
E) 0.062 mm

Question 11

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:

Accepted Answer

A) " $\pi$/4" 
B) " $\pi$/2" 
C) "3 $\pi$/4" 
D) " $\pi$" 
E) 2 $\pi$" 
A) " $\pi$/4" 
B) " $\pi$/2" 
C) "3 $\pi$/4" 
D) " $\pi$" 
E) 2 $\pi$"

Question 12

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:

Accepted Answer

A) the fringe system disappears 
B) the bright fringes get brighter and the dark ones get darker 
C) the fringes just get dimmer 
D) the dark fringes just get brighter 
E) the dark fringes get brighter and the bright ones get darker 
A) the fringe system disappears 
B) the bright fringes get brighter and the dark ones get darker 
C) the fringes just get dimmer 
D) the dark fringes just get brighter 
E) the dark fringes get brighter and the bright ones get darker

Question 13

Two light waves are initially in phase and have the same wavelength, 470 nm.They enter two different media of identical lengths of 2.50 µm.If n1 = 1.2 and n2 = 1.5, what is the effective phase difference of the waves when they exit the media?

Accepted Answer

A) 0 rad 
B) 0.6 rad 
C) 1.6 rad 
D) 3.7 rad 
E) 10 rad 
A) 0 rad 
B) 0.6 rad 
C) 1.6 rad 
D) 3.7 rad 
E) 10 rad

Question 14

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:

Accepted Answer

A) halve the slit separation 
B) double the slit separation 
C) double the width of each slit 
D) halve the width of each slit 
E) none of these 
A) halve the slit separation 
B) double the slit separation 
C) double the width of each slit 
D) halve the width of each slit 
E) none of these

Question 15

Interference of light is evidence that:

Accepted Answer

A) the speed of light is very large 
B) light is a transverse wave 
C) light is electromagnetic in character 
D) light is a wave phenomenon 
E) light does not obey conservation of energy 
A) the speed of light is very large 
B) light is a transverse wave 
C) light is electromagnetic in character 
D) light is a wave phenomenon 
E) light does not obey conservation of energy

Question 16

A light wave with an electric field amplitude of 2E0 and a phase constant of zero is to be combined with one of the following waves.Which of these combinations produces the least intensity?

Accepted Answer

A) wave A has an amplitude of E0 and a phase constant of zero 
B) wave B has an amplitude of E0 and a phase constant of  $\pi$ 
C) wave C has an amplitude of 2E0 and a phase constant of zero 
D) wave D has an amplitude of 2E0 and a phase constant of  $\pi$ 
E) wave E has an amplitude of 3E0 and a phase constant of  $\pi$ 
A) wave A has an amplitude of E0 and a phase constant of zero 
B) wave B has an amplitude of E0 and a phase constant of  $\pi$ 
C) wave C has an amplitude of 2E0 and a phase constant of zero 
D) wave D has an amplitude of 2E0 and a phase constant of  $\pi$ 
E) wave E has an amplitude of 3E0 and a phase constant of  $\pi$

Question 17

In a thin film experiment, a wedge of air is used between two glass plates.If the wavelength of the incident light in air is 480 nm, how much thicker is the air wedge at the 16th dark fringe than it is at the 6th?

Accepted Answer

A) 240 nm 
B) 480 nm 
C) 2400 nm 
D) 4800 nm 
E) none of these 
A) 240 nm 
B) 480 nm 
C) 2400 nm 
D) 4800 nm 
E) none of these

Question 18

Light from a small region of an ordinary incandescent bulb 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?

Accepted Answer

A) Use slits that are closer together 
B) Use a light source of lower intensity 
C) Use a light source of higher intensity 
D) Use a blue filter instead of a yellow filter 
E) Move the light source further away from the slits 
A) Use slits that are closer together 
B) Use a light source of lower intensity 
C) Use a light source of higher intensity 
D) Use a blue filter instead of a yellow filter 
E) Move the light source further away from the slits

Question 19

Two point sources, vibrating in phase, produce an interference pattern in a ripple tank.If the frequency is increased by 20%, the number of nodal lines:

Accepted Answer

A) is increased by 20% 
B) is increased by 40% 
C) remains the same 
D) is decreased by 20% 
E) is decreased by 40% 
A) is increased by 20% 
B) is increased by 40% 
C) remains the same 
D) is decreased by 20% 
E) is decreased by 40%

Question 20

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 $\lambda$ denotes the wavelength of the incident light in air, what is the thinnest possible such coating?

Accepted Answer

A) 0.5$\lambda$ 
B) 0.417$\lambda$ 
C) 0.3$\lambda$ 
D) 0.25$\lambda$ 
E) 0.208$\lambda$ 
A) 0.5$\lambda$ 
B) 0.417$\lambda$ 
C) 0.3$\lambda$ 
D) 0.25$\lambda$ 
E) 0.208$\lambda$

Exam 35: Interference

In a Michelson interferometer, in order to shift the pattern by half a fringe, one of the mirrors at the end of an arm must be moved by:

To obtain an observable double-slit fringe pattern:

In a Young's double-slit experiment, the separation between slits is d and the screen is a distance D from the slits.D is much greater than d and λ\lambdaλ is the wavelength of the light.The number of bright fringes per unit length on the screen is:

A thin film with an index of refraction of 1.60 is placed in one of the beams of a Michelson interferometer.If this causes a shift of 8 bright fringes in the pattern produced by light of wavelength 580 nm, what is the thickness of the film?

The reason there are two slits, rather than one, in a Young's experiment is:

The phase difference between the two waves which give rise to a dark spot in a Young's double-slit experiment is (where m = integer):

In a Young's experiment, it is essential that the two beams:

The three factors that determine the interference of reflected waves from a thin film are:

Three experiments involving a thin film (in air)are shown.If t denotes the film thickness and λ\lambdaλ denotes the wavelength of the light in the film, which experiments will produce constructive interference as seen by the observer?

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:

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:

Two light waves are initially in phase and have the same wavelength, 470 nm.They enter two different media of identical lengths of 2.50 µm.If n1 = 1.2 and n2 = 1.5, what is the effective phase difference of the waves when they exit the media?

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:

Interference of light is evidence that:

A light wave with an electric field amplitude of 2E0 and a phase constant of zero is to be combined with one of the following waves.Which of these combinations produces the least intensity?

In a thin film experiment, a wedge of air is used between two glass plates.If the wavelength of the incident light in air is 480 nm, how much thicker is the air wedge at the 16th dark fringe than it is at the 6th?

Light from a small region of an ordinary incandescent bulb 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?

Two point sources, vibrating in phase, produce an interference pattern in a ripple tank.If the frequency is increased by 20%, the number of nodal lines:

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\lambdaλ denotes the wavelength of the incident light in air, what is the thinnest possible such coating?

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Filters

In a Young's double-slit experiment, the separation between slits is d and the screen is a distance D from the slits.D is much greater than d and $\lambda$ is the wavelength of the light.The number of bright fringes per unit length on the screen is:

Two light waves are initially in phase and have the same wavelength, 470 nm.They enter two different media of identical lengths of 2.50 µm.If n₁ = 1.2 and n₂ = 1.5, what is the effective phase difference of the waves when they exit the media?

A light wave with an electric field amplitude of 2E₀ and a phase constant of zero is to be combined with one of the following waves.Which of these combinations produces the least intensity?