Chapter 26: The Refraction of Light

Brewster angle

The angle of incidence for which the reflected light is 100% plane-polarized parallel to the reflecting surface.

You are sitting by the shore of a lake on a sunny and windless day. When are your Polaroid sunglasses most effective in reducing the glare of the sunlight reflected from the lake surface? When the angle of incidence of the sunlight on the lake is ________. (a)almost 90 because the sun is low in the sky (b) 0 because the sun is directly overhead (c)somewhere between 90 and 0

(c)somewhere between 0 and 90 (They are most effective when the angle of incidence is the Brewster angle and the reflected light is 100% polarized.)

A converging lens is used to produce a real image, as in Figure 26.27a. A piece of black tape is then placed over the upper half of the lens. Which one of the following statements is true concerning the image that results with the tape in place? (a)The image is of the entire object, although its brightness is reduced since fewer rays produce it. (b)The image is of the object's lower half only, but its brightness is not reduced. (c)The image is of the object's upper half only, but its brightness is not reduced.

A

Which one of the following statements concerning refraction of light by a prism is true? a) Light of higher frequency is refracted more than light of lower frequency. b) Light of lower frequency is refracted more than light of higher frequency. c) All light is refracted the same amount because the index of refraction of the prism is a constant for all frequencies.

A

Which one of the following statements concerning refraction of light by a prism is true? a) Light of higher frequency is refracted more than light of lower frequency. b) Light of lower frequency is refracted more than light of higher frequency. c) All light is refracted the same amount because the index of refraction of the prism is a constant for all frequencies.

A

When light travels from a higher to a lower index of refraction, the refracted ray is bent [TOWARDS / AWAY FROM ] the normal. n1>n2

Away

Two blocks, made from the same transparent material, are immersed in different liquids. A ray of light strikes each block at the same angle of incidence but the angle of refraction is greater in A than B. From the drawing, determine which liquid has the lower index of refraction.

B

Which of the following optical devices have the ability to produce an upright, virtual and smaller image? (Circle all that apply.) a) a converging lens b) a diverging lens c) a convex mirror d) a plane mirror e) a concave mirror f) None of the above.

B and C

A beam of light passes from air into water. Which is necessarily true? a) The frequency is unchanged and the wavelength increases. b) The frequency is unchanged and the wavelength decreases. c) The wavelength is unchanged and the frequency decreases. d) Both the wavelength and frequency increase. e) Both the wavelength and frequency decrease.

B) The frequency is unchanged and the wavelength decreases.

When an object is placed 25 cm from a lens, a virtual image is formed. Which one(s) of the following conclusions is incorrect? (There may be more than one answer.) a) The image is upright. b) The lens must be a converging lens. c) The image may be reduced or enlarged. d) If the lens is converging the image distance can be less than 25 cm. e) If the lens is diverging the image distance must be less than 25 cm.

B/D

White light enters a glass prism, but the color components of the light are observed to emerge from the prism. What phenomena is this due to?

Dispersion

A man is fishing from a dock, using a bow and arrow. To strike a fish that he sees beneath the water, should he aim (a)somewhat above the fish, (b)directly at the fish, or (c)somewhat below the fish

C

What does one observe on the screen in a Young's experiment if white light illuminates the double slit instead of light of a single wavelength? a) a white central fringe and no other fringes b) a dark central fringe and a series of alternating white and dark fringes on each side of the center c) a white central fringe and a series of colored and dark fringes on each side of the center d) a continuous band of colors with no dark fringes anywhere e) a dark screen since no constructive interference can occur

C

A mirror (R = 100 cm) produces an upright image whose distance from the mirror is three times the object distance. What type of mirror is being used?

Concave since the image is upright and further away

The various colors of visible light differ in a) frequency only. b) wavelength only. c) their speeds in a vacuum. d) both frequency and wavelength. e) both frequency and their speed in a vacuum

D

When an object is placed 20 cm from a diverging lens, a reduced image is formed. Which one of the following statements is necessarily true? a) The image is inverted. b) The image could be real. c) The image distance must be greater than 20 cm. d) The focal length of the lens may be less than 20 cm. e) The refractive power of the lens must be greater than 0.05 diopters.

D

Which one of the following statements concerning the index of refraction for a given material is true? a) The index of refraction may be less than 1. b) The index of refraction may be measured in nanometers. c) The index of refraction does not depend on the frequency of the incident light. d) For a given frequency, the index of refraction is inversely proportional to the wavelength of light in the material. e) For a given frequency, the index of refraction is inversely proportional to the wavelength of light in vacuum.

D

What optical phenomena we discussed is responsible for "chromatic aberration"? Do lenses, mirrors, both or neither, suffer from chromatic aberration? In a sentence, explain why.

Dispersion Applies only to lenses

T/F Changing the distance of an image from a lens causes the focal length of the lens to change

False The focal length only depends on the geometry and composition of the lens

Without his contact lenses, a student can focus from 0.80 m to infinity. The student is [ nearsighted / farsighted ] and needs [ converging / diverging ] lenses to correct this.

Farsighted converging

spherical aberration

Inability of spherical mirror to focus all parallel rays to a single point

If total internal reflection is to occur, what must the incident angle be relative to the critical angle?

It must be larger than or equal to the critical angle.

When light travels from one medium into another, which of the following parameters changes: speed, frequency, wavelength?

The speed and wavelength change but the frequency doesn't.

Snell's Law of Refraction

When light travels from a material with refractive index n1 into a material with refractive index n2, the refracted ray, the incident ray, and the normal to the interface between the materials all lie in the same plan

Farsightedness

a condition in which faraway objects are seen more clearly than near objects because the image of near objects is focused behind the retina -can be corrected by converging lenses

Nearsighted

a condition in which nearby objects are seen more clearly than distant objects because distant objects focus in front of the retina -can be corrected by diverging lenses

Explain how rainbows occur a) name the specific phenomena at work b) state what physically causes it

a) Caused by dispersion b) Light enters the raindrop, reflects off of the side of the drop and exits. In the process, it is broken into a spectrum just like it is in a triangular glass prism. Light is slowing down and bending as it goes from air to denser water.

At any value past the critical angle

all the light will be refracted into the medium

diverging lens

causes incident parallel rays to diverge after exiting the lens A lens that is thinner in the middle than at the edges, causing parallel rays passing through it to diverge as if from a point similar to a convex mirror

Converging lenses are ______ at the center than at the edges, whereas diverging lenses are _____ at the center

converging are thicker at the center diverging are thinner at the center

If the incident ray does not strike the interface at normal incidence, the transmitted ray has a ________ direction than the incident ray

different

The problem of resolution arises due to the optical phenomena of

diffraction

The index of refraction depends on _____ but ____ doesn't change when moving from one medium into the next

frequency but frequency doesn't change when moving from one medium to the next

Total internal reflection occurs only when the beam of light has an angle of incidence that is_______than the critical angle

greater

The ______ the index of refraction for a given color, the ______ the bending

greater the index of refraction the greater the bending

chromatic aberration

the focusing of different colors of light at different distances behind a lens

If n1>n2, then the angle of refraction is ________ than the angle of incidence

larger

Lenses differ from mirrors, in that light can pass through a lens from

left to right or from right to left

converging lens

lens such that a beam of light passing through it is brought to a point or focus a lens that is thickest in the middle causing parallel light rays to come together at a point similar to a concave mirror

If values of n are greater than unity the speed of light in a material medium is ______ than it is in a vacuum

less than

Light travels through the material at a speed that is ______ , the actual speed depending on the nature of the material.

less than

If you are farsighted, your [ NEAR POINT / FAR POINT ] is not what it should be, and your eye focuses light [ IN FRONT / BEHIND ] your retina. To correct this problem, you'd need corrective lenses that were [ CONVERGING / DIVERGING ].

near point behind converging

When the object is placed between 2F and F , for a converging lens, the image is

real, inverted, but enlarged

When the object is located OUTSIDE the focal point (2F), the image generated by a converging lens will be [ REAL / VIRTUAL ], [UPRIGHT / INVERTED] and [SMALLER /SAME SIZE / LARGER]

real, inverted, smaller

refraction

the bending of a wave as it enters a new medium at an angle It is the change in direction of wave when it passes through a medium.

Total internal reflection

the complete reflection that takes place within a substance when the angle of incidence of light striking the surface boundary is less than the critical angle -occurs only when light travels from a higher-index medium toward a lower-index medium

index of refraction

the extent to which the speed of light in a material medium differs from that in a vacuum

Dispersion of light

the separation of light into its component colors using a prism or diffraction grating spreading of light into its color components

The higher index of refraction

the smaller the angle (bends towards normal)

If n1<n2 then the angle of refraction is ______ than the angle of incidence

then the angle of refraction is always smaller than the angle of incidence.

When light travels from a lower to a higher index of refraction, the refracted ray is bent [TOWARDS / AWAY FROM ] the normal. n1<n2

towards

When light strikes the interface between two transparent materials, the light generally divides into ________ parts. Part of the light is ________ and the remainder is

two parts part is reflected and the other part is refracted

When the object is located INSIDE the focal point, the image generated by a converging lens will be [ REAL / VIRTUAL ], [UPRIGHT / INVERTED] and [SMALLER /SAME SIZE / LARGER]

virtual, upright, enlarged

The image generated by a diverging lens will always be [ REAL / VIRTUAL ], [UPRIGHT / INVERTED] and [SMALLER /SAME SIZE / LARGER]

virtual, upright, smaller