Question 1

What do we mean when we say that two light rays striking a screen are in phase with each other?

Accepted Answer

A)  When the electric field due to one is a maximum, the electric field due to the other is also a maximum, and this relation is maintained as time passes. 
B)  They are traveling at the same speed. 
C)  They have the same wavelength. 
D)  They alternately reinforce and cancel each other. 
A)  When the electric field due to one is a maximum, the electric field due to the other is also a maximum, and this relation is maintained as time passes. 
B)  They are traveling at the same speed. 
C)  They have the same wavelength. 
D)  They alternately reinforce and cancel each other.

Question 2

When a beam of light that is traveling in glass strikes an air boundary at the surface of the glass, there is

Accepted Answer

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. 
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 3

A single-slit diffraction pattern is formed on a distant screen. Assuming the angles involved are small, by what factor will the width of the central bright spot on the screen change if the wavelength of the illuminating light is doubled?

Accepted Answer

A)  It will be cut to one-quarter its original size. 
B)  It will be cut in half. 
C)  It will double. 
D)  It will become four times as large. 
E)  It will become eight times as large. 
A)  It will be cut to one-quarter its original size. 
B)  It will be cut in half. 
C)  It will double. 
D)  It will become four times as large. 
E)  It will become eight times as large.

Question 4

Monochromatic coherent light shines through a pair of slits. If the distance between these slits is decreased, which of the following statements are true of the resulting interference pattern? (There could be more than one correct choice.)

Accepted Answer

A)  The distance between the maxima stays the same. 
B)  The distance between the maxima decreases. 
C)  The distance between the minima stays the same. 
D)  The distance between the minima increases. 
E)  The distance between the maxima increases. 
A)  The distance between the maxima stays the same. 
B)  The distance between the maxima decreases. 
C)  The distance between the minima stays the same. 
D)  The distance between the minima increases. 
E)  The distance between the maxima increases.

Question 5

When light travels from air into water,

Accepted Answer

A)  its velocity, wavelength and frequency all change. 
B)  its velocity changes, but its frequency and wavelength do not change. 
C)  its frequency changes, but its velocity and wavelength do not change. 
D)  its velocity and wavelength change, but its frequency does not change. 
E)  its wavelength changes, but its velocity and frequency do not change. 
A)  its velocity, wavelength and frequency all change. 
B)  its velocity changes, but its frequency and wavelength do not change. 
C)  its frequency changes, but its velocity and wavelength do not change. 
D)  its velocity and wavelength change, but its frequency does not change. 
E)  its wavelength changes, but its velocity and frequency do not change.

Question 6

A beam of light of wavelength 600 nm is incident normally on a diffraction grating with a spacing between slits of 1.70 × 10-4 cm. At what angle away from the centerline does a first-order maximum occur?

Accepted Answer

A)  10.5° 
B)  12.1° 
C)  16.4° 
D)  18.2° 
E)  20.7° 
A)  10.5° 
B)  12.1° 
C)  16.4° 
D)  18.2° 
E)  20.7°

Question 7

A round 0.85-mm-diameter hole is illuminated by infrared light of wavelength 2.5 μm What is the angle of the first dark fringe in the resulting pattern?

Accepted Answer

A)  0.21 degrees 
B)  3.6 × 10-3 degrees 
C)  1.2 × 10-2 degrees 
D)  4.8 × 10-2 degrees 
A)  0.21 degrees 
B)  3.6 × 10-3 degrees 
C)  1.2 × 10-2 degrees 
D)  4.8 × 10-2 degrees

Question 8

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

Accepted Answer

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. 
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 9

In a double-slit interference experiment you are asked to use laser light of different wavelengths and determine the separation between adjacent maxima. You observe that this separation is greatest when you illuminate the double slit with

Accepted Answer

A)  blue light. 
B)  green light. 
C)  yellow light. 
D)  red light. 
E)  The separation is the same for all wavelengths. 
A)  blue light. 
B)  green light. 
C)  yellow light. 
D)  red light. 
E)  The separation is the same for all wavelengths.

Question 10

An optical engineer needs to ensure that the bright fringes from a double-slit are 15.7 mm apart on a detector that is 1.70 ${~m}$ from the slits. If the slits are illuminated with coherent light of wavelength 633 nm, how far apart should the slits be?

Accepted Answer

A)  68.5 μm 
B)  74.0 μm 
C)  79.5 μm 
D)  63.0 μm 
A)  68.5 μm 
B)  74.0 μm 
C)  79.5 μm 
D)  63.0 μm

Question 11

When a beam of light, originally traveling in air, enters a piece of glass having an index of refraction of 3/2, its frequency

Accepted Answer

A)  increases by a factor of 3/2. 
B)  is reduced to 2/3 its original value. 
C)  is unaffected. 
A)  increases by a factor of 3/2. 
B)  is reduced to 2/3 its original value. 
C)  is unaffected.

Question 12

The wavelength of light in a thin film is 360 nm and the wavelength of light in vacuum is 469 nm. What is the index of refraction for the film?

Accepted Answer

A)  1.10 
B)  1.30 
C)  1.50 
D)  1.70 
E)  1.90 
A)  1.10 
B)  1.30 
C)  1.50 
D)  1.70 
E)  1.90

Question 13

A 360-nm thick oil film floats on the surface of a pool of water water. The indices of refraction of the oil and the water are 1.5 and 1.33, respectively. When the surface of the oil is illuminated from above at normal incidence with white light, what are the two wavelengths of light between 400 nm to 800 nm wavelength that are most strongly reflected?

Accepted Answer

A)  410 nm and 700 nm 
B)  430 nm and 720 nm 
C)  450 nm and 740 nm 
D)  470 nm and 760 nm 
E)  490 nm and 780 nm 
A)  410 nm and 700 nm 
B)  430 nm and 720 nm 
C)  450 nm and 740 nm 
D)  470 nm and 760 nm 
E)  490 nm and 780 nm

Question 14

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 nonzero thickness of the film to see a bright reflection?

Accepted Answer

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

Question 15

Monochromatic light of wavelength 500 nm is incident normally on a diffraction grating. If the third-order maximum of the diffraction pattern is observed at 32.0°, what is the total number of maxima can be seen?

Accepted Answer

A)  5 
B)  7 
C)  10 
D)  11 
E)  8 
A)  5 
B)  7 
C)  10 
D)  11 
E)  8

Question 16

Red light with a wavelength of 650 nm travels from air into a liquid with an index of 1.33. What are the frequency and wavelength of the light in the liquid? (c = 3.0 × 108 m/s)

Accepted Answer

4.61 × 10¹⁴

Question 17

A pair of narrow slits that are 1.8 mm apart is illuminated by a monochromatic coherent light source. A fringe pattern is observed on a screen 4.8 m from the slits. If there are 5.0 bright fringes/cm on the screen, what is the wavelength of the monochromatic light?

Accepted Answer

A)  550 nm 
B)  600 nm 
C)  650 nm 
D)  700 nm 
E)  750 nm 
A)  550 nm 
B)  600 nm 
C)  650 nm 
D)  700 nm 
E)  750 nm

Question 18

A metallic sheet has a large number of parallel slits, 5.0 mm wide and 20 cm apart. This sheet is used as a diffraction grating for microwaves. A wide parallel beam of microwaves is incident normally on the sheet. What is the smallest microwave frequency for which only the central maximum will occur? (c = 3.00 × 108 m/s)

Accepted Answer

A)  0.50 GHz 
B)  0.70 GHz 
C)  1.0 GHz 
D)  1.5 GHz 
E)  2.0 GHz 
A)  0.50 GHz 
B)  0.70 GHz 
C)  1.0 GHz 
D)  1.5 GHz 
E)  2.0 GHz

Question 19

In a two-slit experiment using coherent light, the distance between the slits and the screen is 1.10 m, and the distance between the slits is 0.0400 mm. If the second order bright fringe is measured to be 4.20 cm from the centerline on the screen, what is the wavelength of light?

Accepted Answer

A)  200 nm 
B)  381 nm 
C)  401 nm 
D)  620 nm 
E)  763 nm 
A)  200 nm 
B)  381 nm 
C)  401 nm 
D)  620 nm 
E)  763 nm

Question 20

If a sheet containing a single thin slit is heated (without damaging it) and therefore expands, what happens to the width of the central bright diffraction region on a distant screen?

Accepted Answer

A)  It gets narrower. 
B)  It gets wider. 
C)  It doesn't change. 
A)  It gets narrower. 
B)  It gets wider. 
C)  It doesn't change.

Exam 17: Wave Optics

What do we mean when we say that two light rays striking a screen are in phase with each other?

When a beam of light that is traveling in glass strikes an air boundary at the surface of the glass, there is

A single-slit diffraction pattern is formed on a distant screen. Assuming the angles involved are small, by what factor will the width of the central bright spot on the screen change if the wavelength of the illuminating light is doubled?

Monochromatic coherent light shines through a pair of slits. If the distance between these slits is decreased, which of the following statements are true of the resulting interference pattern? (There could be more than one correct choice.)

When light travels from air into water,

A beam of light of wavelength 600 nm is incident normally on a diffraction grating with a spacing between slits of 1.70 × 10-4 cm. At what angle away from the centerline does a first-order maximum occur?

A round 0.85-mm-diameter hole is illuminated by infrared light of wavelength 2.5 μm What is the angle of the first dark fringe in the resulting pattern?

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

In a double-slit interference experiment you are asked to use laser light of different wavelengths and determine the separation between adjacent maxima. You observe that this separation is greatest when you illuminate the double slit with

An optical engineer needs to ensure that the bright fringes from a double-slit are 15.7 mm apart on a detector that is 1.70 m{~m} m from the slits. If the slits are illuminated with coherent light of wavelength 633 nm, how far apart should the slits be?

When a beam of light, originally traveling in air, enters a piece of glass having an index of refraction of 3/2, its frequency

The wavelength of light in a thin film is 360 nm and the wavelength of light in vacuum is 469 nm. What is the index of refraction for the film?

Monochromatic light of wavelength 500 nm is incident normally on a diffraction grating. If the third-order maximum of the diffraction pattern is observed at 32.0°, what is the total number of maxima can be seen?

Red light with a wavelength of 650 nm travels from air into a liquid with an index of 1.33. What are the frequency and wavelength of the light in the liquid? (c = 3.0 × 108 m/s)

A pair of narrow slits that are 1.8 mm apart is illuminated by a monochromatic coherent light source. A fringe pattern is observed on a screen 4.8 m from the slits. If there are 5.0 bright fringes/cm on the screen, what is the wavelength of the monochromatic light?

In a two-slit experiment using coherent light, the distance between the slits and the screen is 1.10 m, and the distance between the slits is 0.0400 mm. If the second order bright fringe is measured to be 4.20 cm from the centerline on the screen, what is the wavelength of light?

If a sheet containing a single thin slit is heated (without damaging it) and therefore expands, what happens to the width of the central bright diffraction region on a distant screen?

Representing Motion

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Thermal Properties of Matter

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Relativity

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Filters

A beam of light of wavelength 600 nm is incident normally on a diffraction grating with a spacing between slits of 1.70 × 10^-4 cm. At what angle away from the centerline does a first-order maximum occur?

An optical engineer needs to ensure that the bright fringes from a double-slit are 15.7 mm apart on a detector that is 1.70 ${~m}$ from the slits. If the slits are illuminated with coherent light of wavelength 633 nm, how far apart should the slits be?

Red light with a wavelength of 650 nm travels from air into a liquid with an index of 1.33. What are the frequency and wavelength of the light in the liquid? (c = 3.0 × 10⁸ m/s)