Question 1

In a Young's double-slit experiment the center of a bright fringe occurs wherever waves from the slits differ in the distance they travel by a multiple of:

Accepted Answer

A) a fourth of a wavelength 
B) a half a wavelength 
C) three-fourths of a wavelength 
D) a wavelength 
E) none of the above 
A) a fourth of a wavelength 
B) a half a wavelength 
C) three-fourths of a wavelength 
D) a wavelength 
E) none of the above

Question 2

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 
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 3

Light from a point source X contains only blue and red components.After passing through a mysterious box, the light falls on a screen.Red and blue hands are observed as shown.The box must contain:

Accepted Answer

A) a lens 
B) a mirror 
C) a prism 
D) a double slit 
E) a blue and red filter 
A) a lens 
B) a mirror 
C) a prism 
D) a double slit 
E) a blue and red filter

Question 4

An air wedge is formed using two glass plates that are in contact along their left edge.When viewed by highly monochromatic light, there are exactly 4001 dark bands in the reflected light.The air is now evacuated (with the glass plates remaining rigidly fixed)and the number of dark bands decreases to exactly 4000.The index of refraction of the air is:

Accepted Answer

A) 0.00025 
B) 0.00050 
C) 1.00025 
D) 1.00050 
E) 1.00000, by definition 
A) 0.00025 
B) 0.00050 
C) 1.00025 
D) 1.00050 
E) 1.00000, by definition

Question 5

If the speed of light is c, and the index of refraction of a material is n, what is the speed of light in the material?

Accepted Answer

A) c 
B) c/n 
C) nc 
D) n 
E) n/c 
A) c 
B) c/n 
C) nc 
D) n 
E) n/c

Question 6

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 7

The light waves represented by the three rays shown in the diagram all have the same frequency.4.7 wavelengths fit into layer 1, 3.2 wavelengths fit into layer 2, and 5.3 wavelengths fit into layer 3.Rank the layers according to the speeds of the waves, least to greatest.

Accepted Answer

A) 1, 2, 3 
B) 2, 1, 3 
C) 3, 1, 2 
D) 3, 2, 1 
E) 1, 3, 2 
A) 1, 2, 3 
B) 2, 1, 3 
C) 3, 1, 2 
D) 3, 2, 1 
E) 1, 3, 2

Question 8

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 
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 9

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 10

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

Question 11

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 12

Huygens' construction can be used only:

Accepted Answer

A) for light 
B) for an electromagnetic wave 
C) if one of the media is vacuum (or air) 
D) for transverse waves 
E) for all of these and other situations 
A) for light 
B) for an electromagnetic wave 
C) if one of the media is vacuum (or air) 
D) for transverse waves 
E) for all of these and other situations

Question 13

If the wavelength of a particular beam of light in vacuum is λ, and the index of refraction of a material is n, what is the wavelength of the light in the material?

Accepted Answer

A) λ 
B) λ/n 
C) nλ 
D) n 
E) n/λ 
A) λ 
B) λ/n 
C) nλ 
D) n 
E) n/λ

Question 14

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 15

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 16

In a Young's double-slit experiment, the slit separation is doubled.To maintain the same fringe spacing on the screen, the screen-to-slit distance D must be changed to:

Accepted Answer

A) D/2 
B)    
C)    
D) 2D 
E) 4D 
A) D/2 
B)    
C)    
D) 2D 
E) 4D

Question 17

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$\lambda$

Question 18

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. 
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 19

Waves from two slits are in phase at the slits and travel to a distant screen to produce the second minimum of the interference pattern.The difference in the distance traveled by the wave is:

Accepted Answer

A) half a wavelength 
B) a wavelength 
C) three halves of a wavelength 
D) two wavelengths 
E) three wavelengths 
A) half a wavelength 
B) a wavelength 
C) three halves of a wavelength 
D) two wavelengths 
E) three wavelengths

Question 20

Red light is viewed through a thin vertical soap film.At the third dark area shown, the thickness of the film, in terms of the wavelength $\lambda$within the film, is:

Accepted Answer

A) "$\lambda$/4" 
B) "$\lambda$/2" 
C) "$\lambda$" 
D) "3$\lambda$/4" 
E) "5$\lambda$/4" 
A) "$\lambda$/4" 
B) "$\lambda$/2" 
C) "$\lambda$" 
D) "3$\lambda$/4" 
E) "5$\lambda$/4"

Exam 35: Interference 1

In a Young's double-slit experiment the center of a bright fringe occurs wherever waves from the slits differ in the distance they travel by a multiple of:

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:

Light from a point source X contains only blue and red components.After passing through a mysterious box, the light falls on a screen.Red and blue hands are observed as shown.The box must contain:

If the speed of light is c, and the index of refraction of a material is n, what is the speed of light in the material?

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?

The light waves represented by the three rays shown in the diagram all have the same frequency.4.7 wavelengths fit into layer 1, 3.2 wavelengths fit into layer 2, and 5.3 wavelengths fit into layer 3.Rank the layers according to the speeds of the waves, least to greatest.

If two light waves are coherent:

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:

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 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?

Huygens' construction can be used only:

If the wavelength of a particular beam of light in vacuum is λ, and the index of refraction of a material is n, what is the wavelength of the light in the material?

Interference of light is evidence that:

In a Young's double-slit experiment, the slit separation is doubled.To maintain the same fringe spacing on the screen, the screen-to-slit distance D must be changed to:

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?

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

Waves from two slits are in phase at the slits and travel to a distant screen to produce the second minimum of the interference pattern.The difference in the distance traveled by the wave is:

Red light is viewed through a thin vertical soap film.At the third dark area shown, the thickness of the film, in terms of the wavelength λ\lambdaλ within the film, is:

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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 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: