Question 1

A monochromatic light source illuminates a double slit and the resulting interference pattern is observed on a distant screen. Let d be the center-to-center slit spacing, a the individual slit width, D the screen-to-slit distance, and ℓ the adjacent dark line spacing in the interference pattern. The wavelength of the light is then:

Accepted Answer

A)   
B)   
C)   
D)   
E)    A

Question 2

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

Question 3

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 D

Question 4

When light travels from one medium into a different medium with a different index of refraction,

Accepted Answer

A)   the frequency, wavelength, and speed all change.
B)   the frequency and wavelength change but the speed stays the same.
C)   the speed and wavelength change but the frequency stays the same.
D)   the speed and frequency change but the wavelength stays the same.
E)   only the speed changes; the frequency and the wavelength stay the same.

Question 5

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

Question 6

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

Question 7

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)     π\piπ /4
B)     π\piπ /2
C)   3  π\piπ /4
D)     π\piπ 
E)   2  π\piπ

Question 8

A glass (n = 1.6) lens is coated with a thin film (n = 1.3) to reduce reflection of certain incident light. If $\lambda$ is the wavelength of the light in the film, the least film thickness is:

Accepted Answer

A)   less than  λ\lambdaλ /4
B)    λ\lambdaλ /4
C)    λ\lambdaλ /2
D)    λ\lambdaλ 
E)   more than  λ\lambdaλ

Question 9

An air wedge is formed from two glass plates which are in contact at their left edges. There are ten dark bands when viewed by reflection using monochromatic light. The left edge of the top plate is now slowly lifted until the plates are parallel. During this process:

Accepted Answer

A)   the dark bands crowd toward the right edge
B)   the dark bands remain stationary
C)   the dark bands crowd toward the left edge
D)   the dark bands spread out, disappearing off the right edge
E)   the dark bands spread out, disappearing off the left edge

Question 10

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

Question 11

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

Question 12

A soap film is illuminated by white light normal to its surface. The index of refraction of the film is 1.50. Wavelengths of 480 nm and 800 nm and no wavelengths between are intensified in the reflected beam. The thickness of the film is:

Accepted Answer

A)   1.5 *10-5 cm
B)   2.4 * 10-5 cm
C)   3.6 *10-5 cm
D)   4.0*10-5 cm
E)   6.0* 10-5 cm

Question 13

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:

Accepted Answer

A)   increases by a factor of 4/3
B)   increases by a factor of 3
C)   remains the same
D)   decreases to 3/4 of its original value
E)   decreases to 1/3 of its original value

Question 14

Yellow light is viewed by reflection from a thin vertical soap film. Let $\lambda$ be the wavelength of the light within the film. Why is there a large dark space at the top of the film?

Accepted Answer

A)   no light is transmitted through this part of the film
B)   the film thickness there is λ\lambdaλ /4
C)   the light reflected from exactly one of the two surfaces undergoes a 180  °\degree°  phase change
D)   the film is too thick in this region for thin film formulas to apply
E)   the reflected light is in the infrared

Question 15

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

Question 16

A light wave with an electric field amplitude of E0 and a phase constant of zero is to be combined with one of the following waves. Which of these combinations produces the greatest 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   π\piπ 
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   π\piπ 
E)   wave E has an amplitude of 3E0 and a phase constant of   π\piπ

Question 17

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

Question 18

If two light waves are coherent:

Accepted Answer

A)   their amplitudes are the same
B)   their frequencies are the same
C)   their wavelengths are the same
D)   their phase difference is constant
E)   the difference in their frequencies is constant

Question 19

Binoculars and microscopes are frequently made with coated optics by adding a thin layer of transparent material to the lens surface as shown, in order to improve light transmission. One wants:

Accepted Answer

A)   constructive interference between waves 1 and 2
B)   destructive interference between waves 3 and 4
C)   constructive interference between waves 3 and 4
D)   the coating to be more transparent than the lens
E)   the speed of light in the coating to be less than that in the lens

Question 20

In a Young's double-slit experiment, light of wavelength 500 nm illuminates two slits which are separated by 1 mm. The separation between adjacent bright fringes on a screen 5 m from the slits is:

Accepted Answer

A)   0.10 cm
B)   0.25 cm
C)   0.50 cm
D)   1.0 cm
E)   none of the above

Exam 35: Interference

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:

To obtain an observable double-slit fringe pattern:

When light travels from one medium into a different medium with a different index of refraction,

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

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:

A glass (n = 1.6) lens is coated with a thin film (n = 1.3) to reduce reflection of certain incident light. If $\lambda$ is the wavelength of the light in the film, the least film thickness is:

An air wedge is formed from two glass plates which are in contact at their left edges. There are ten dark bands when viewed by reflection using monochromatic light. The left edge of the top plate is now slowly lifted until the plates are parallel. During this process:

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:

A soap film is illuminated by white light normal to its surface. The index of refraction of the film is 1.50. Wavelengths of 480 nm and 800 nm and no wavelengths between are intensified in the reflected beam. The thickness of the film is:

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:

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

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?

If two light waves are coherent:

Binoculars and microscopes are frequently made with coated optics by adding a thin layer of transparent material to the lens surface as shown, in order to improve light transmission. One wants:

In a Young's double-slit experiment, light of wavelength 500 nm illuminates two slits which are separated by 1 mm. The separation between adjacent bright fringes on a screen 5 m from the slits is:

Exam 35: Interference

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:

To obtain an observable double-slit fringe pattern:

When light travels from one medium into a different medium with a different index of refraction,

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

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:

A glass (n = 1.6) lens is coated with a thin film (n = 1.3) to reduce reflection of certain incident light. If λ\lambdaλ is the wavelength of the light in the film, the least film thickness is:

An air wedge is formed from two glass plates which are in contact at their left edges. There are ten dark bands when viewed by reflection using monochromatic light. The left edge of the top plate is now slowly lifted until the plates are parallel. During this process:

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:

A soap film is illuminated by white light normal to its surface. The index of refraction of the film is 1.50. Wavelengths of 480 nm and 800 nm and no wavelengths between are intensified in the reflected beam. The thickness of the film is:

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:

Yellow light is viewed by reflection from a thin vertical soap film. Let λ\lambdaλ be the wavelength of the light within the film. Why is there a large dark space at the top of the film?

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:

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

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?

If two light waves are coherent:

Binoculars and microscopes are frequently made with coated optics by adding a thin layer of transparent material to the lens surface as shown, in order to improve light transmission. One wants:

In a Young's double-slit experiment, light of wavelength 500 nm illuminates two slits which are separated by 1 mm. The separation between adjacent bright fringes on a screen 5 m from the slits is:

A glass (n = 1.6) lens is coated with a thin film (n = 1.3) to reduce reflection of certain incident light. If $\lambda$ is the wavelength of the light in the film, the least film thickness is:

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