Question 1

When projected through a single lens, the image of a movie on a screen is

Accepted Answer

A)  real and inverted. 
B)  virtual and inverted. 
C)  real and upright. 
D)  virtual and upright. 
E)  virtual and enlarged.

Question 2

The critical angle for total internal reflection is the

Accepted Answer

A)  single angle for which transmission through the boundary is zero. 
B)  maximum angle of incidence, below which no light is transmitted through the boundary. 
C)  minimum angle of incidence, above which no light is transmitted through the boundary. 
D)  minimum or maximum angle, depending on which of the indices of refraction is larger.

Question 3

An innovative physics professor conducts laboratory exercises in the college swimming pool. The professor places a submersible laser under water (n = 1.33) and aims the beam at a crystal, which is also under water. The reflected beam is found to be totally polarized when the angle of incidence of the beam is 57 degrees. What is the index of refraction of the crystal?

Accepted Answer

A)  1.17 
B)  1.12 
C)  1.54 
D)  2.05

Question 4

A 1.76 m tall man looks at his reflection in a plane mirror. He stands 4.2 m away from the mirror. How far from his eyes are the images of his feet? Assume his eyes are 5 cm below the top of his head.

Accepted Answer

A)  8.4 m 
B)  11.1 m 
C)  4.2 m 
D)  4.53 m 
E)  8.57 m

Question 5

In a laboratory experiment, a rectangular tank made of a transparent solid is filled with an unknown liquid. A submersible laser is placed in the tank, with the beam directed toward the liquid-solid interface at the bottom. By adjusting the aim of the laser, you find that the reflected ray is fully polarized when the angle of incidence is 54°. What is the angle of refraction of the ray transmitted into the solid tank bottom in this case?

Accepted Answer

A)  39° 
B)  47° 
C)  can't answer this without knowing the indices of refraction. 
D)  36°

Question 6

You are experimentally determining the critical angle for a novel transparent solid whose index of refraction is less than that of water (n=1.33) but greater than that of air (n=1.00). Your experimental method involves underwater work in which you observe whether there is any transmitted ray at the water/solid interface as you vary the angle of incidence on the solid surface. When your device reaches an incident angle of 53 degrees you find that the transmitted ray inside the solid vanishes. What is the index of refraction for this new solid?

Accepted Answer

A)  1.16 
B)  0.57 
C)  1.06 
D)  0.53

Question 7

A coin has been dropped inadvertently into a bucket full of cleaning fluid (n=1.13). The bottom of the bucket is 15 cm below the surface. How far beneath the surface does the coin appear to be?

Accepted Answer

A)  17.0 cm 
B)  13.3 cm 
C)  More information is needed 
D)  7.5 cm

Question 8

An optical fiber having index of refraction 1.40 is clad with a material of index of refraction 1.25. What is the critical angle in the fiber at the fiber-cladding interface?

Accepted Answer

A)  63.2° 
B)  26.8° 
C)  41.8° 
D)  73.0° 
E)  16.5°

Question 9

When light goes from a material with a lower index of refraction n1 into a material with a higher index of refraction n2 with an angle of incidence of 30.0°, which of the following is true?

Accepted Answer

A)  the angle of refraction is more than 30.0° and total internal reflection is not possible 
B)  the angle of refraction is less than 30.0° and total internal reflection is not possible 
C)  the angle of refraction is more than 30.0° and total internal reflection may occur 
D)  the angle of refraction is less than 30.0° and total internal reflection may occur

Question 10

In a camera, the image focused on the film is

Accepted Answer

A)  real and upright. 
B)  real and inverted. 
C)  virtual and upright. 
D)  virtual and inverted. 
E)  technically a mirage.

Question 11

A light ray strikes the surface of sapphire (n = 1.77) at an angle of incidence of 40.0°. What angle of refraction results?

Accepted Answer

A)  21.3° 
B)  50.0° 
C)  59.7° 
D)  57.0° 
E)  17.7°

Question 12

A light ray in air strikes a glass surface with an angle of incidence of 30.0°. The angle of refraction in the glass is 20.0°. What is the index of refraction of the glass?

Accepted Answer

A)  1.67 
B)  1.55 
C)  1.52 
D)  1.46 
E)  1.24

Question 13

An object placed farther from a converging lens than the focal point always produces an image that is

Accepted Answer

A)  the same size as the object. 
B)  inverted. 
C)  virtual. 
D)  smaller than the object.

Question 14

When light in material 1, which is in contact with material 2, undergoes total internal reflection, what condition is necessary for their indices of refraction?

Accepted Answer

A)  n1 = 2 n2 
B)  n1 > n2 
C)  n1 2 
D)  n1 = n2 + 1 
E)  n2 = 1.5

Question 15

A ray of light enters an equilateral prism made of material with n = 1.45 What angle of incidence θ will cause the internally refracted ray to be parallel to the base of the prism?

Accepted Answer

A)  46.5° 
B)  30.0° 
C)  20.2° 
D)  5.70° 
E)  this cannot happen

Question 16

A light ray in air strikes a glass surface with an angle of incidence of 30.0°. The angle of refraction in the glass is 20.0°. What is the angle between the reflected ray and the refracted ray?

Accepted Answer

A)  60° 
B)  70° 
C)  120° 
D)  130° 
E)  140°

Question 17

An object placed closer to a converging lens than the focal point always produces an image that is

Accepted Answer

A)  the same size as the object. 
B)  smaller than the object. 
C)  virtual. 
D)  inverted.

Question 18

A light ray reflects from a surface. If the angle of incidence is 24°, what is the angle between the reflected ray and the incident ray at the surface?

Accepted Answer

A)  24° 
B)  12° 
C)  66° 
D)  48° 
E)  102°

Question 19

Two vertical plane mirrors are joined at a right angle. A horizontal beam of light is shone on one of the mirrors at an angle of incidence of 22 degrees, such that the reflected ray strikes the other mirror. What is the angle of incidence of the beam that strikes the second mirror?

Accepted Answer

A)  23° 
B)  68° 
C)  43° 
D)  22°

Question 20

A mirror has a focal length −20 cm. If an object is placed 10 cm in front of the mirror, where will the image form?

Accepted Answer

A)  20 cm in front of the mirror 
B)  20 cm behind the mirror 
C)  6.7 in front of the mirror 
D)  6.7 behind the mirror 
E)  no image will form

Exam 23: Reflection and Refraction of Light