Deck 23: Reflection and Refraction of Light

Question 1

According to Huygens's principle, every point on a wave front acts as a source of a new waves of what kind?

A) transverse
B) spherical
C) longitudinal
D) sinusoidal
E) plane

Answer 1

spherical

Question 2

A diver below the surface of a lake notices that no light appears to be coming toward her from angles greater than θ, measured from the vertical. If the index of refraction of water is 1.33, what is the angle θ?

A) 30.0°
B) 36.9°
C) 41.2°
D) 48.8°
E) 53.1°

Answer 2

48.8°

Question 3

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?

A) 60°
B) 70°
C) 120°
D) 130°
E) 140°

Answer 3

130°

Question 4

A light ray reflects from a surface. If the angle of incidence is 24°, what is the angle that the reflected ray makes with the surface?

A) 24°
B) 12°
C) 66°
D) 48°
E) 102°

Question 5

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 speed of light in the glass?

A) 3.00 × 10⁸ m/s
B) 2.50 × 10⁸ m/s
C) 2.33 × 10⁸ m/s
D) 2.05 × 10⁸ m/s
E) 1.50 × 10⁸ m/s

Question 6

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?

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

Question 7

A ray of light enters an equilateral prism made of material with n = 1.45 at an angle of incidence θ. The internally refracted ray is parallel to the base of the prism. What is the angle of refraction for the ray leaving the prism?

A) 46.5°
B) 30.0°
C) 20.2°
D) 15.7°
E) the ray won't leave the prism

Question 8

A small object is encased in an acrylic block (n = 1.5). The object appears to be 4.0 cm below the surface. What is the actual distance of the object below the surface?

A) 2.0 cm
B) 2.7 cm
C) 4.0 cm
D) 5.5 cm
E) 6.0 cm

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?

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

Which of the following best describes the greatest known value for index of refraction?

A) 1.5
B) just less than 2
C) 2
D) a value greater than 2 but not greater than 3
E) a value greater than 3

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?

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

Question 12

When a light ray in water (n = 1.33) enters glass with index of refraction 1.60, what is the greatest angle of refraction that can occur?

A) 90.0°
B) 56.2°
C) 52.2°
D) 38.7°
E) 0.0°

Question 13

A ray of light enters a pane of glass with an angle of incidence of 37°. The index of refraction of the glass is 1.48. What is the angle of refraction as the ray emerges from the other side of the pane after traveling through the glass?

A) 21°
B) 24°
C) 53°
D) 37°
E) 16°

Question 14

When a light ray in air enters glass with index of refraction 1.60, what is the greatest angle of refraction that can occur?

A) 90.0°
B) 56.2°
C) 52.2°
D) 38.7°
E) 0.0°

Question 15

What is the critical angle for diamond (n = 2.42) in air?

A) 2.42°
B) 67.5°
C) 65.6°
D) 24.4°
E) 37.1°

Question 16

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?

A) 24°
B) 12°
C) 66°
D) 48°
E) 102°

Question 17

Specular reflection occurs whenever

A) rays reflect from a surface.
B) rays reflect in all directions from a surface.
C) rays reflect at only one angle from a surface.
D) parallel rays all reflect at the same angle from a surface.
E) visible light rays reflect.

Question 18

A ray of light enters a pane of glass with an angle of incidence of 37°. The index of refraction of the glass is 1.48. What is the angle of incidence as the ray reaches the glass-air interface on the far side of the pane coming from inside the glass?

A) 21°
B) 24°
C) 53°
D) 37°
E) 16°

Question 19

A light ray in material 1 goes into material 2. The angle of incidence in material 1 is 40.0° and the angle of refraction in material 2 is 31.0°. If the index of refraction of material 1 is 1.60, what is the index of refraction of material 2?

A) 3.20
B) 2.00
C) 1.88
D) 1.41
E) 1.20

Question 20

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?

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

Question 21

When light is totally polarized by reflection at an interface between two materials where the index of refraction for the incident medium is n₁ and for the other is n₂, the incident angle is given by θ = tan^-1(n₂/n₁). This equation holds

A) only when n₂ > n₁.
B) only when n₁ > n₂.
C) only when n₂ > n₁ + 1.
D) only when n₂ < n₁ + 1.
E) for all values of n₁ and n₂.

Question 22

A 6.0 cm tall object is placed 20 cm in front of a convex mirror with focal length −100 cm. What is the size of the image formed?

A) 5.0 cm
B) 7.2 cm
C) 7.5 cm
D) 30 cm
E) 12 cm

Question 23

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?

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

Question 24

A 9.0 cm object is placed in front of a mirror and the image formed is upright, behind the mirror, and 3.0 cm in size. Which of the following statements is true?

A) the magnification is 1/3 and the image is real
B) the magnification is −1/3 and the image is real
C) the magnification is 1/3 and the image is virtual
D) the magnification is −1/3 and the image is virtual

Question 25

A 6.0 cm tall object is placed 20 cm in front of a convex mirror with focal length −100 cm. Where is the image formed?

A) 80 cm behind the mirror
B) 25 cm behind the mirror
C) 17 cm behind the mirror
D) 17 cm in front of the mirror
E) 25 cm in front of the mirror

Question 26

A convex mirror has a radius of 10 cm. What is its focal length?

A) 10 cm
B) 5.0 cm
C) 20 cm
D) −5.0 cm
E) −10 cm

Question 27

At what angle above the horizon would the sun appear if its reflected light from a lake, viewed at the same time, were completely polarized? (n_water = 1.333)

A) 53.12°
B) 36.88°
C) 48.75°
D) 41.25°
E) 23.52°

Question 28

When you see your image in a plane mirror, your image appears to be

A) in front of the mirror.
B) at the surface of the mirror.
C) behind the surface of the mirror at a distance equal to your distance from the mirror.
D) behind the surface of the mirror at a distance equal to half your distance from the mirror.

Question 29

An object is placed 60 cm in front of a mirror and the image is upright and ¼ the size of the object. What is the focal length of the mirror?

A) −12 cm
B) −20 cm
C) −45 cm
D) −75 cm
E) some positive value not given

Question 30

A concave mirror has an object placed 40 cm in front of it. An image forms 60 cm in front of the mirror. What is the focal length of the mirror?

A) 60 cm
B) 120 cm
C) −120 cm
D) 100 cm
E) 24 cm

Question 31

A light ray goes through two thick rectangular slabs of glass, each of the same uniform thickness. The first slab has index of refraction n₁ and the second n₂. If n₁ < n₂. How does the original angle of incidence θ_i into the first slab compare to the final angle of refraction θ_f where the ray leaves the second slab going back into air?

A) θ_i > θ_f
B) θ_i < θ_f
C) θ_i = θ_f
D) θ_i = (n₁/n₂)θ_f
E) more information is needed

Question 32

If a reflected ray in air at an angle of reflection of 60° is totally polarized, what is the index of refraction of the reflecting material?

A) 1.50
B) 2.00
C) 1.73
D) 1.15
E) this angle is not possible for an incident ray in air

Question 33

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?

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

Question 34

When total internal reflection happens at a glass-air interface

A) half the light is refracted.
B) half the light is reflected.
C) light hits the interface from the air side.
D) light hits the interface from the glass side.
E) the law of reflection ceases to hold.

Question 35

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?

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

Question 36

As you walk at 1.5 m/s toward a mirrored wall in a department store, how fast are approaching your image?

A) 1.5 m/s
B) 3.0 m/s
C) 6.0 m/s
D) 0.75 m/s
E) 0.0 the image stays at a constant distance

Question 37

A concave mirror has a 12 cm tall object placed 40 cm in front of it. An image forms 60 cm in front of the mirror. What is the size and orientation of the image?

A) 8.0 cm, inverted
B) 8.0 cm, upright
C) 18 cm, inverted
D) 18 cm, upright
E) 24 cm, upright

Question 38

In a camera, the image focused on the film is

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

Question 39

The critical angle for Lucite is 41.8°. What is Brewster's angle for Lucite?

A) 33.7°
B) 26.3°
C) 48.2°
D) 56.3°
E) Brewster's angle does not exist for this material

Question 40

A 6.0 cm tall object is placed 20 cm in front of a convex mirror with focal length −100 cm. Which of the following describes the image?

A) real and inverted
B) real and upright
C) virtual and inverted
D) virtual and upright
E) not possible to determine

Question 41

A building 30 m tall is being photographed with a camera with a lens of focal length 50 mm. How tall is the image if the building is 100 m away?

A) 30 mm
B) 15 mm
C) 10 mm
D) 3.0 mm
E) 1.0 mm

Question 42

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?

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

Question 43

A thin lens of focal length −12.5 cm has a 5.0 cm tall object placed 10 cm in front of it. What are the size and orientation of the image?

A) 4.0 cm, inverted
B) 4.0 cm, upright
C) 2.8 cm, inverted
D) 2.8 cm, upright
E) 100 cm, inverted

Question 44

It is found that at a laser bounced off the surface of a liquefied gas is completely polarized when the angle of incidence of the laser beam is 45.70 degrees from the vertical. What is the index of refraction of this material?

A) 1.43
B) 1.397
C) 1.412
D) 1.091
E) 1.025

Question 45

Which of these statements is true for the image formed by an object placed in front of a thin lens?

A) Convex lenses never produce virtual images.
B) Real images are always enlarged.
C) Real images are always inverted.
D) Virtual images are always inverted.

Question 46

A point-like object is placed at the focal point of a converging lens, so the light rays emerging from the lens will be parallel to the principal axis. The object is now moved closer to the lens. Which statement is true about the light rays from the lens?

A) They will remain parallel to the principal axis.
B) They converge toward each other.
C) They emerge parallel to each other but not to the principal axis.
D) They diverge from each other.

Question 47

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

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

Question 48

A laser beam is directed at a horizontal glass surface with an angle of incidence of 57 degrees. If the angle of refraction is 38 degrees, at what incident angle will the reflected beam be fully polarized?

A) 46°
B) 36°
C) 54°
D) 43°

Question 49

A thin lens of focal length −12.5 cm has a 5.0 cm tall object placed 10 cm in front of it. Where is the image located?

A) 2.5 cm behind the lens
B) 5.6 cm behind the lens
C) 5.6 cm in front of the lens
D) 50 cm behind the lens
E) 50 cm in front of the lens

Question 50

A thin lens of focal length 12.5 cm has a 5.0 cm tall object placed 10 cm in front of it. What are the size and orientation of the image?

A) 4.0 cm, inverted
B) 4.0 cm, upright
C) 8.9 cm, inverted
D) 8.9 cm, upright
E) 25 cm, upright

Question 51

A laser beam reflected from a horizontal glass surface is found to be totally polarized when the angle of incidence of the beam is 57 degrees. What is the angle of refraction of the transmitted beam in this case?

A) 29°
B) 43°
C) 33°
D) 40°

Question 52

Which of these statements is true for the image formed by a spherical mirror?

A) Real images are always inverted.
B) Virtual images of real objects are always in front of the mirror.
C) Virtual images of real objects are always upright.
D) Real images are always behind the mirror.

Question 53

How does Brewster's angle for a given interface compare to the critical angle for total internal reflection from the same surface (assuming n2 < n1, so that total internal reflection is possible)?

A) Brewster's angle is always greater than the critical angle.
B) Brewster's angle can be either greater than or less than the critical angle.
C) Brewster's angle is always less than the critical angle.
D) The two angles are always equal.

Question 54

Fiber optic cable is in the form of a cylindrical core of fiber with index of refraction 1.67 surrounded by a layer of cladding of index 1.45. What is the maximum angle for light rays inside the fiber core with respect to the cable's axis for which the light will be fully transmitted thanks to total internal reflection?

A) 29.7°
B) 60.3°
C) 36.8°
D) 53.2°

Question 55

In order to produce an image twice the size of an object with a converging lens of focal length f, what object distance should be used?

A) f
B) f/2
C) 2f
D) 2f/3
E) 3f/2

Question 56

The critical angle for total internal reflection is the

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 57

A thin lens of focal length 12.5 cm has a 5.0 cm tall object placed 10 cm in front of it. Where will the image be formed?

A) 2.5 cm behind the lens
B) 5.6 cm behind the lens
C) 5.6 cm in front of the lens
D) 50 cm behind the lens
E) 50 cm in front of the lens

Question 58

A 25 cm focal length mirror has a 3.0 cm tall object placed 20 cm in front of it. Where is the image, and is it real or virtual?

A) 5.0 cm behind the mirror, virtual
B) 11 cm in front of the mirror, real
C) 100 cm in front of the mirror, real
D) 100 cm behind the mirror, virtual
E) 45 cm behind the mirror, virtual

Question 59

A lens of focal length f is used to project an image of a solar eclipse onto a flat sheet of paper. To get the clearest image, how far from the lens should be paper be?

A) f/2
B) f
C) 2f
D) more than 10f
E) less than f/10

Question 60

A 25 cm focal length mirror has a 3.0 cm tall object placed 20 cm in front of it. What is the size of the image and is it upright or inverted?

A) 1.0 cm, upright
B) 3.8 cm, inverted
C) 2.4 cm, inverted
D) 15 cm, upright
E) 12 cm, upright

Question 61

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?

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

Question 62

You are conducting an experiment with a converging lens and have set it up to produce a real image of a distant tree. If you cover the top half of the lens with opaque paper, what occurs?

A) The bottom half of the image is missing.
B) Nothing happens.
C) The image becomes half as large.
D) The image is complete, but dimmer than it was.
E) The top half of the image is missing.

Question 63

When a real object is reflected in a plane mirror, the image is always

A) virtual.
B) real.
C) inverted.
D) None of these

Question 64

Of the following distances, which is the closest an object can be to a lens of focal length f and still produce a real image? (Note this is not the smallest possible distance, just the smallest of the provided choices.)

A) 3f
B) 2f
C) 1.2f
D) 0.8f
E) 0.49f

Question 65

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

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

Question 66

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 horizontally toward the vertically oriented transparent polycarbonate side wall of the pool. The laser is shone on the pool wall at an angle of incidence of 42 degrees with respect to the normal, and at that angle the reflected ray is found to be completely polarized. What is the index of refraction of the polycarbonate side wall?

A) 1.11
B) 1.28
C) 1.20
D) 1.48

Question 67

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?

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

Question 68

If an object is placed before a single thin lens

A) real images are always enlarged.
B) virtual images are always inverted.
C) real images are always inverted.
D) convex lenses never create virtual images.

Question 69

The image of a real object formed by a diverging lens is always

A) real.
B) inverted.
C) larger than the object.
D) virtual.

Question 70

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?

A) 23°
B) 68°
C) 43°
D) 22°

Question 71

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.

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

Question 72

When a light ray meets an interface between two media, how does the angle of refraction (assuming there is a transmitted ray) compare to the angle of incidence?

A) The angle of refraction is always less than the angle of incidence.
B) The angle of refraction is always greater than the angle of incidence.
C) It may be greater than, equal to, or less than the angle of incidence.
D) The angles are equal.

Question 73

An innovative physics professor conducts laboratory exercises in the college swimming pool. The professor places a submersible laser under water (n = 1.3) and aims the beam at a block of glass (n = 1.5), which is also under water. At what angle of incidence will the reflected beam be totally polarized?

A) 61°
B) 49°
C) 41°
D) 39°

Question 74

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

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

Question 75

A fish looking straight upward spots a berry on a tree branch above the surface of a pond. The fish is at rest 15 cm below the surface, while the berry is positioned 1.5 m above the surface. The index of refraction of water is 1.33. How far away does the berry appear to be from the fish's perspective?

A) 2.15 m
B) 2.0 m
C) 1.65 m
D) 1.5 m

Question 76

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?

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

Question 77

When looking at your own reflection in a plane mirror, you notice that you can't see your whole body. You adjust the position of the mirror on the wall, but you still can't see yourself completely. In order to see a larger fraction of your body, what could you do?

A) can do nothing about it with this mirror
B) get farther from the mirror
C) tilt the mirror
D) get closer to the mirror