Deck 22: Electromagnetic Waves

Question 1

Choose the one alternative that best completes the statement or answers the question.
Which one of the following sets of characteristics describes the image formed by a plane mirror?

A) virtual and larger than the object
B) virtual and inverted
C) real and upright
D) virtual and upright
E) real and inverted

Answer 1

D

Question 2

Choose the one alternative that best completes the statement or answers the question.
A light beam has speed $c$ in vacuum and speed $v$ in a certain plastic. The index of refraction $n$ of this plastic is

A) $n = ( c / v ) ^ { 2 }$ .
B) $n = c / v$ .
C) $n = ( v / c ) ^ { 2 }$ .
D) $n = v / c$ .
E) $n = c v$ .

Answer 2

B

Question 3

Choose the one alternative that best completes the statement or answers the question.
Suppose you place an object in front of a concave mirror. Which of the following statements must be true? (There could be more than one correct choice.)

A) If you position the object between the mirror and the focal point of the mirror, its image must be upright and virtual.
B) No matter where you place the object, a real image of the object will be formed.
C) The image of the object will always be smaller than the object.
D) The image of the object will always be inverted.
E) No matter where you place the object, the image of the object will always be virtual and upright.

Answer 3

A

Question 4

A) Mirrors always produce real images because they reflect light.
B) A virtual image cannot be photographed.
C) A virtual image cannot be viewed by the unaided eye.
D) A real image must be erect.
E) A virtual image cannot be formed on a screen.
Answer: E
The focal length of a concave mirror has a magnitude of 20 cm. What is its radius of curvature?

A) -20 cm
B) 20 cm
C) -40 cm
D) 10 cm
E) 40 cm

Question 5

Choose the one alternative that best completes the statement or answers the question.
If the index of refraction of a material is 2, this means that light travels

A) 2 times as fast in air as it does in vacuum.
B) 2 times as fast in vacuum as it does in the material.
C) 2 times as fast in the material as it does in air.
D) 1/2 as fast in air as it does in the material.
E) 2 times as fast in the material than it does in vacuum.

Question 6

Choose the one alternative that best completes the statement or answers the question.
The image formed in a plane mirror is

A) at a shorter distance behind the mirror than the distance the object is in front of the mirror.
B) at the same distance behind the mirror as the object is in front of the mirror.
C) at the same distance in front of the mirror as the object is in front of the mirror.
D) a real image behind the mirror.
E) at a larger distance behind the mirror than the distance the object is in front of the mirror.

Question 7

A) Mirrors always produce real images because they reflect light.
B) A virtual image cannot be photographed.
C) A virtual image cannot be viewed by the unaided eye.
D) A real image must be erect.
E) A virtual image cannot be formed on a screen.
Answer: E
The focal length of a convex mirror is has a magnitude of 20 cm. What is its radius of curvature?

A) -20 cm
B) -10 cm
C) 40 cm
D) 20 cm
E) -40 cm

Question 8

Choose the one alternative that best completes the statement or answers the question.
You may have seen ambulances on the street with the letters of the word AMBULANCE written on the front of them, in such a way as to appear correctly when viewed in your car's rear-view
Mirror. (See the figure.) How do the letters appear when you look directly at the ambulance (not
Through the mirror)? a) $\forall$ WดกาซNวE
b) $\mathrm { MB } \cup \perp А И ว \exists$
c) ECNALUBMA
d) $\exists ว N \forall า \cap \& W \forall$
e) ヨวИA」บดMA

A) $\mathrm { a }$
B) $b$
C) $\mathrm { c }$
D) $\mathrm { d }$
E) e

Question 9

Choose the one alternative that best completes the statement or answers the question.
A beam of light traveling in air strikes a glass slab at an angle of incidence less than 90°. After entering the glass slab, what does the beam of light do? (There could be more than one correct
Choice.)

A) It follows the normal to the glass slab.
B) I follows the same path as before it struck the glass.
C) It bends away from the normal at the point of contact.
D) It slows down.
E) It bends closer to the normal at the point of contact.

Question 10

A) Mirrors always produce real images because they reflect light.
B) A virtual image cannot be photographed.
C) A virtual image cannot be viewed by the unaided eye.
D) A real image must be erect.
E) A virtual image cannot be formed on a screen.
Answer: E
If a spherical convex mirror has a radius of curvature R, the magnitude of its focal length is

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

Question 11

A) Mirrors always produce real images because they reflect light.
B) A virtual image cannot be photographed.
C) A virtual image cannot be viewed by the unaided eye.
D) A real image must be erect.
E) A virtual image cannot be formed on a screen.
Answer: E
A negative magnification for a mirror means that

A) the image is inverted, and the mirror is concave.
B) the image is upright, and the mirror could be either concave or convex.
C) the image is inverted, and the mirror is convex.
D) the image is inverted, and the mirror could be either concave or convex.
E) the image is upright, and the mirror is convex.

Question 12

Choose the one alternative that best completes the statement or answers the question.
Light goes from material having a refractive index of $n _ { 1 }$ into a material with refractive index $n _ { 2 }$ . If the refracted light is bent away from the normal, what can you conclude about the indices of refraction?

A) $n _ { 1 } \leq n _ { 2 }$
B) $n 1 \geq n _ { 2 }$
C) $n _ { 1 } > n _ { 2 }$
D) $n _ { 1 } = n _ { 2 }$
E) $n _ { 1 } < n _ { 2 }$

Question 13

Choose the one alternative that best completes the statement or answers the question.
Which one of the following numbers is the correct magnification produced by a plane mirror?

A) 3/2
B) 1/2
C) 2
D) 1
E) 1/4

Question 14

Choose the one alternative that best completes the statement or answers the question.
Light enters glass from air. The angle of refraction will be

A) equal to the angle of incidence.
B) less than the angle of incidence.
C) greater than the angle of incidence.

Question 15

Choose the one alternative that best completes the statement or answers the question.
A lighted candle is placed a short distance from a plane mirror, as shown in the figure. At which location will the image of the flame appear to be located?

A) at $A$
B) at B
C) at $C$
D) at $M$ (at the mirror)

Question 16

Choose the one alternative that best completes the statement or answers the question.
The index of refraction of a type of glass is 1.50, and the index of refraction of water is 1.33. If light enters water from this glass, the angle of refraction will be

A) equal to the angle of incidence.
B) greater than the angle of incidence.
C) less than the angle of incidence.

Question 17

A) Mirrors always produce real images because they reflect light.
B) A virtual image cannot be photographed.
C) A virtual image cannot be viewed by the unaided eye.
D) A real image must be erect.
E) A virtual image cannot be formed on a screen.
Answer: E
If a spherical concave mirror has a radius of curvature R, its focal length is

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

Question 18

Choose the one alternative that best completes the statement or answers the question.
As you walk away from a plane mirror on a wall, the height of your image

A) is always a real image, no matter how far you are from the mirror.
B) changes from being a virtual image to a real image as you pass the focal point.
C) is always the same size.
D) may or may not get smaller, depending on where the observer is positioned.
E) gets smaller.

Question 19

Choose the one alternative that best completes the statement or answers the question.
The critical angle for a beam of light passing from water into air is 48.8°. This means that all light rays with an angle of incidence in the water that is greater than 48.8° will be

A) totally reflected.
B) partially reflected and partially transmitted.
C) totally transmitted.
D) totally absorbed by the water.

Question 20

Choose the one alternative that best completes the statement or answers the question.
Light enters air from water. The angle of refraction will be

A) less than the angle of incidence.
B) greater than the angle of incidence.
C) equal to the angle of incidence.

Question 21

D) you won't see your image because there is none.
E) you will see your image and you will appear larger than you.
Answer: C
Single concave spherical mirrors produce images that

A) are always larger than the actual object.
B) are always real.
C) could be smaller than, larger than, or the same size as the actual object, depending on the placement of the object.
D) are always the same size as the actual object.
E) are always smaller than the actual object.

Question 22

D) you won't see your image because there is none.
E) you will see your image and you will appear larger than you.
Answer: C
A beam of light that is parallel to the principal axis strikes a concave mirror. What happens to the reflected beam of light?

A) It also is parallel to the principal axis.
B) It passes through the center of curvature of the mirror.
C) It passes between the focal point and the center of curvature of the mirror.
D) It is perpendicular to the principal axis.
E) It passes through the focal point of the mirror.

Question 23

Choose the one alternative that best completes the statement or answers the question.
If a object is placed between a convex lens and its focal point, the image formed is

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

Question 24

D) you won't see your image because there is none.
E) you will see your image and you will appear larger than you.
Answer: C
Suppose you wanted to start a fire using a mirror to focus sunlight. Which of the following statements is most accurate?

A) It would be best to use a convex mirror.
B) One cannot start a fire using a mirror, since mirrors form only virtual images.
C) It would be best to use a plane mirror.
D) It would be best to use a concave mirror, with the object to be ignited positioned halfway between the mirror and its center of curvature.
E) It would be best to use a concave mirror, with the object to be ignited positioned at the center of curvature of the mirror.

Question 25

D) you won't see your image because there is none.
E) you will see your image and you will appear larger than you.
Answer: C
Single convex spherical mirrors produce images that

A) are always smaller than the actual object.
B) are always larger than the actual object.
C) are sometimes real.
D) could be larger than, smaller than, or the same size as the actual object, depending on the placement of the object.
E) are always the same size as the actual object.

Question 26

A) Mirrors always produce real images because they reflect light.
B) A virtual image cannot be photographed.
C) A virtual image cannot be viewed by the unaided eye.
D) A real image must be erect.
E) A virtual image cannot be formed on a screen.
Answer: E
A convex mirror has a focal length of magnitude $f$ . An object is placed in front of this mirror at a point $\frac { 2 } { 3 } f$ from the face of the mirror. The image will appear

A) inverted and enlarged.
B) upright and enlarged.
C) inverted and reduced.
D) upright and reduced.
E) behind the mirror.

Question 27

Choose the one alternative that best completes the statement or answers the question.
A convex lens has focal length $f$ . If an object is placed at a distance of $2 f$ from the lens on the principal axis, the image is located at a distance from the lens

A) of $2 f$ .
B) between the lens and $f$ .
C) between $f$ and $2 f$ .
D) of infinity.
E) of $f$ .

Question 28

Choose the one alternative that best completes the statement or answers the question.
Starting from very far away, an object is moved closer and closer to a converging lens, eventually reaching the lens. What happens to its image formed by that lens? (There could be more than one
Correct choice.)

A) The image gets farther and farther from the lens.
B) The image eventually changes from real to virtual.
C) The image keeps getting larger and larger.
D) The image eventually changes from virtual to real.
E) The image gets closer and closer to the lens.

Question 29

Choose the one alternative that best completes the statement or answers the question.
A convex lens has focal length $f$ . If an object is located at "infinity" (very far away), the image formed is located at a distance from the lens

A) of $f$ .
B) between the lens and $f$ .
C) between $f$ and $2 f$ .
D) of $2 f$ .
E) of infinity.

Question 30

Choose the one alternative that best completes the statement or answers the question.
Which of the following terms describe lenses that are thinner at the center than at the edges? (There could be more than one correct choice.)

A) converging lenses
B) convex lenses
C) diverging lenses
D) concave lenses

Question 31

A) Mirrors always produce real images because they reflect light.
B) A virtual image cannot be photographed.
C) A virtual image cannot be viewed by the unaided eye.
D) A real image must be erect.
E) A virtual image cannot be formed on a screen.
Answer: E
If an object is placed at the center of curvature of concave mirror, the image formed by the mirror is located

A) between the center of curvature and the focal point.
B) out beyond the center of curvature.
C) at the center of curvature.
D) at infinity.
E) at the focal point.

Question 32

A) Mirrors always produce real images because they reflect light.
B) A virtual image cannot be photographed.
C) A virtual image cannot be viewed by the unaided eye.
D) A real image must be erect.
E) A virtual image cannot be formed on a screen.
Answer: E
Which of the following statements about spherical mirrors is correct? (There could be more than one correct choice.)

A) A convex mirror always produces a virtual image.
B) A concave mirror always produces a virtual image.
C) A convex mirror always produces a real image.
D) A convex mirror always produces an upright image.
E) A concave mirror always produces a real image.

Question 33

A) Mirrors always produce real images because they reflect light.
B) A virtual image cannot be photographed.
C) A virtual image cannot be viewed by the unaided eye.
D) A real image must be erect.
E) A virtual image cannot be formed on a screen.
Answer: E
An object is placed to the left of a spherical mirror in front of the mirror. If the image of the object is formed on the right side of the mirror, which of the following statements must be true? (There
Could be more than one correct choice.)

A) The image is upright and the mirror must be convex.
B) The image is upright and virtual.
C) The mirror could be either concave or convex.
D) The image is upright and the mirror must be concave.
E) The image is inverted and real, and the mirror must be convex.

Question 34

Choose the one alternative that best completes the statement or answers the question.
A convex lens has focal length $f$ . If an object is placed at a distance between $f$ and $2 f$ from the lens on the principal axis, the image is located at a distance from the lens

A) that is greater than $2 f$ .
B) of infinity.
C) of $2 f$ .
D) between $f$ and $2 f$ .
E) of $f$ .

Question 35

D) you won't see your image because there is none.
E) you will see your image and you will appear larger than you.
Answer: C
An upright object is 50 cm from a concave mirror of radius 60 cm. The character of the image is

A) real and inverted
B) virtual and inverted
C) real and upright
D) virtual and upright

Question 36

D) you won't see your image because there is none.
E) you will see your image and you will appear larger than you.
Answer: C
A beam of light that is parallel to the principal axis strikes a convex mirror. What happens to the reflected beam of light?

A) It appears to be coming from the focal point on the other side of the mirror.
B) It appears to be coming from a point between the focal point and the center of curvature of the mirror.
C) It also is parallel to the principal axis.
D) It is perpendicular to the principal axis.
E) It appears to be coming from the center of curvature of the mirror.

Question 37

Choose the one alternative that best completes the statement or answers the question.
Which of the following terms describe lenses that are thicker at the center than at the edges? (There could be more than one correct choice.)

A) converging lenses
B) convex lenses
C) concave lenses
D) diverging lenses

Question 38

D) you won't see your image because there is none.
E) you will see your image and you will appear larger than you.
Answer: C
Sometimes when you look into a curved mirror you see a magnified image (a great big you) and sometimes you see a diminished image (a little you). If you look at the bottom (convex) side of a
Shiny spoon, what will you see?

A) You will see a little you, upside down.
B) You will either see a little you or a great big you, depending on how near you are to the spoon.
C) You won't see an image of yourself because no image will be formed.
D) You will see a little you, right side up.
E) You will see a little you, but whether you are right side up or upside down depends on how near you are to the spoon.

Question 39

Choose the one alternative that best completes the statement or answers the question.
A convex lens has focal length $f$ . If an object is placed at a distance beyond $2 f$ from the lens on the principal axis, the image is located at a distance from the lens

A) of infinity.
B) between $f$ and $2 f$ .
C) between the lens and $f$ .
D) of $f$ .
E) of $2 f$ .

Question 40

Write the word or phrase that best completes each statement or answers the question.
A thin lens projects an image of a man as shown in the figure. Rays marked A, B, and C travel to the lens from the man's ear. Draw the paths of these three rays after they have passed through the lens. Note that $\mathrm { A }$ is parallel to the principal axis, B goes through the center of the lens, C goes through the focal point on the left, and the point marked $f$ is the focal point on the right of the lens.

Question 41

Choose the one alternative that best completes the statement or answers the question.
Starting from very far away, an object is moved closer and closer to a diverging lens, eventually reaching the lens. What happens to its image formed by that lens? (There could be more than one
Correct choice.)

A) The image keeps getting larger and larger.
B) The image eventually changes from real to virtual.
C) The image always remains virtual.
D) The image gets closer and closer to the lens.
E) The image gets farther and farther from the lens.

Question 42

Write the word or phrase that best completes each statement or answers the question.
A thin laser beam traveling in air strikes the surface of a glass plate at $41.2 ^ { \circ }$ with the normal. In the plate, this beam makes an angle of $22.4 ^ { \circ }$ with the normal. What is the speed of light in this glass? $\left( c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$

Question 43

Choose the one alternative that best completes the statement or answers the question.
Which of following statements about the image formed by a single diverging lens are true? (There could be more than one correct choice.)

A) The image is always virtual.
B) The image is always real.
C) The image is always upright.
D) The image is always smaller than the object.
E) The image is always inverted.

Question 44

Write the word or phrase that best completes each statement or answers the question.
A plastic cube is immersed in water having an index of refraction of $1.33$ . A laser beam in the plastic strikes the interface at an angle of $14.5 ^ { \circ }$ with the normal in the plastic. In the water, this beam makes an angle of $21.8 ^ { \circ }$ with the normal. What is the speed of light in the plastic cube? $\left( c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$

Question 45

Write the word or phrase that best completes each statement or answers the question.
The index of refraction for a certain material is $1.399$ for red light and $1.432$ for blue light. Light containing both of these colors is traveling in vacuum and strikes a flat sheet of this material. Find the angle separating the two colors in the refracted light in the sheet if the angle of incidence is $60.00 ^ { \circ }$ .

Question 46

Choose the one alternative that best completes the statement or answers the question.
Which of following statements about the image formed by a single converging lens are true? (There could be more than one correct choice.)

A) The image is always upright.
B) The image is always virtual.
C) The image is always inverted.
D) The image is always real.
E) None of the above choices are correct.

Question 47

C) Yes because the rays that appear to come from a virtual image can be focused by the eye just
like those from an object.
D) No, since the rays that seem to emanate from a virtual image do not in fact emanate from the
image.
Answer: C
An object is placed on the left side of a thin lens, and the image of this object is formed on the left side of the lens. Which of the following statements must be true? (There could be more than one
Correct choice.)

A) The image is inverted and real.
B) The lens must be a converging lens, and the image is upright.
C) The image is upright and virtual.
D) The lens could be either a converging or a diverging lens, and the image is upright.
E) The lens must be a diverging lens, and the image is upright.

Question 48

C) Yes because the rays that appear to come from a virtual image can be focused by the eye just
like those from an object.
D) No, since the rays that seem to emanate from a virtual image do not in fact emanate from the
image.
Answer: C
Which statement about a single thin lens is correct?

A) A converging lens always produces a real inverted image.
B) A diverging lens produces a virtual upright image only if the object is located between the lens and its focal point.
C) A diverging lens always produces a virtual upright image.
D) A diverging lens always produces a virtual inverted image.
E) A converging lens sometimes produces a real upright image.

Question 49

C) Yes because the rays that appear to come from a virtual image can be focused by the eye just
like those from an object.
D) No, since the rays that seem to emanate from a virtual image do not in fact emanate from the
image.
Answer: C
If a single lens forms a virtual image of an object, then

A) the lens must be a converging lens.
B) the object must be between the lens and its focal point.
C) the image must be inverted.
D) the lens must be a diverging lens.
E) the lens could be either a diverging or a converging lens.

Question 50

C) Yes because the rays that appear to come from a virtual image can be focused by the eye just
like those from an object.
D) No, since the rays that seem to emanate from a virtual image do not in fact emanate from the
image.
Answer: C
The image formed by a single concave lens

A) is always inverted.
B) could be real or virtual, depending on whether the object distance is smaller or greater than the focal length.
C) is always virtual.
D) could be real or virtual, but is always real when the object is placed at the focal point.
E) is always real.

Question 51

C) Yes because the rays that appear to come from a virtual image can be focused by the eye just
like those from an object.
D) No, since the rays that seem to emanate from a virtual image do not in fact emanate from the
image.
Answer: C
Light having a speed in vacuum of $3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$ enters a liquid of refractive index $2.0$ . In this liquid, its speed will be

A) $0.75 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$
B) $6.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$
C) $1.5 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$
D) $0.67 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$
E) $3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$

Question 52

Choose the one alternative that best completes the statement or answers the question.
A thin beam of light enters a thick plastic sheet from air at an angle of $32.0 ^ { \circ }$ with the normal and continues in the sheet at an angle of $23.0 ^ { \circ }$ with the normal. What is the index of refraction of the plastic?

A) 1.11
B) 0.74
C) 1.28
D) 1.36

Question 53

Write the word or phrase that best completes each statement or answers the question.
A narrow light beam in vacuum contains light of two wavelengths, $480 \mathrm {~nm}$ and $700 \mathrm {~nm}$ . It strikes a flat piece of glass at an angle of incidence of $60.000 ^ { \circ }$ . The index of refraction of the glass is $1.4830$ at $480 \mathrm {~nm}$ and $1.4760$ at $700 \mathrm {~nm}$ . Determine the angle between the two wavelengths as the light travels in the glass.

Question 54

Choose the one alternative that best completes the statement or answers the question.
A beam of light, traveling in air, strikes a plate of transparent material at an angle of incidence of $56.0 ^ { \circ }$ . It is observed that the reflected and refracted beams form an angle of $90.0 ^ { \circ }$ . What is the index of refraction of this material?

A) $1.48$
B) $1.43$
C) $1.44$
D) $1.40$

Question 55

C) Yes because the rays that appear to come from a virtual image can be focused by the eye just
like those from an object.
D) No, since the rays that seem to emanate from a virtual image do not in fact emanate from the
image.
Answer: C
The speed of light in a certain material is measured to be $2.2 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$ . What is the index of refraction of this material? $\left( c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$

A) $1.8$
B) $1.1$
C) $1.4$
D) $1.2$
E) $1.6$

Question 56

Write the word or phrase that best completes each statement or answers the question.
A ray of light (ray $a$ ) in air strikes a flat piece of glass at an angle of $\phi _ { 0 } = 84 ^ { \circ }$ with respect to the normal, as shown in the figure. The index of refraction of the glass is $1.5$ . What is the angle $\theta$ between the reflected ray (ray $b$ ) and refracted ray (ray $c$ ) rays?

Question 57

Choose the one alternative that best completes the statement or answers the question.
If the magnification of a mirror or lens is negative, it means that

A) the image is inverted and smaller than the object.
B) the object is farther from the mirror (or lens) than the image.
C) the image is farther from the mirror (or lens) than the object.
D) the image is inverted.
E) the image is smaller than the object.

Question 58

C) Yes because the rays that appear to come from a virtual image can be focused by the eye just
like those from an object.
D) No, since the rays that seem to emanate from a virtual image do not in fact emanate from the
image.
Answer: C
The index of refraction of a certain glass is measured to be 1.5. What is the speed of light in that glass? $\left( c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$

A) $1.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$
B) $5.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$
C) $4.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$
D) $3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$
E) $2.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$

Question 59

C) Yes because the rays that appear to come from a virtual image can be focused by the eye just
like those from an object.
D) No, since the rays that seem to emanate from a virtual image do not in fact emanate from the
image.
Answer: C
An object is placed in front of a thin lens. Which statements are correct in describing the image formed by the lens? (There could be more than one correct choice.)

A) If the lens is concave, the image must be virtual.
B) If the lens is convex, the image must be real.
C) If the image is real, then it is also inverted.
D) If the lens is convex, the image will never be virtual.
E) If the image is real, then it is also upright.

Question 60

Choose the one alternative that best completes the statement or answers the question.
An oil layer that is 5.0 cm thick is spread smoothly and evenly over the surface of water on a windless day. A light ray from the air above enters the oil at 45° with the normal and then goes
Into the water. What is the angle of refraction of this ray in the water? The index of refraction for
The oil is 1.15, and for water it is 1.33. A) $39 ^ { \circ }$
B) $27 ^ { \circ }$
C) $36 ^ { \circ }$
D) $32 ^ { \circ }$

Question 61

Choose the one alternative that best completes the statement or answers the question.
Light enters a substance from air at $30.0 ^ { \circ }$ to the normal. It continues within the substance at $23.0 ^ { \circ }$ to the normal. What is the critical angle for this substance when it is surrounded by air?

A) $53 ^ { \circ }$
B) $12.6 ^ { \circ }$
C) $51.4 ^ { \circ }$
D) $36.7 ^ { \circ }$

Question 62

Write the word or phrase that best completes each statement or answers the question.
Light in a transparent material that has an index of refraction of 1.333 strikes the boundary
with another transparent material for which the index of refraction is 1.010. What is the
critical angle for total internal reflection between these two materials?

Question 63

Write the word or phrase that best completes each statement or answers the question.
A light ray enters a glass enclosed fish tank. From air it enters the glass at 20° with respect
to the plane of the surface and then emerges into the water. The index for the glass is 1.50
and for water 1.33.
(a) What is the angle of refraction in the glass?
(b) What is the angle of refraction in the water?
(c) Is there any incident angle in air for which the ray will not enter the water due to total
internal reflection? If so, find it.

Question 64

Choose the one alternative that best completes the statement or answers the question.
Light travels from crown glass, with a refractive index of $1.52$ , into water, having a refractive index of $1.33$ ? The critical angle for this interface is closest to which one of the following angles?

A) $53 ^ { \circ }$
B) $42 ^ { \circ }$
C) $57 ^ { \circ }$
D) $61 ^ { \circ }$
E) $48 ^ { \circ }$

Question 65

Choose the one alternative that best completes the statement or answers the question.
A flashlight beam makes an angle of 60° with the plane of the surface of a calm lake before it enters the water. In the water what angle does the beam make with the plane of the surface? The
Index of refraction of water is 1.33. A) $30 ^ { \circ }$
B) $22 ^ { \circ }$
C) $68 ^ { \circ }$
D) $0 ^ { \circ }$
Е) $60 ^ { \circ }$

Question 66

Choose the one alternative that best completes the statement or answers the question.
As shown in the figure, a laser positioned on a ship is used to communicate with a small research submarine resting on the bottom of a lake. The laser is positioned $12 \mathrm {~m}$ above the surface of the water, and it strikes the water $20 \mathrm {~m}$ from the side of the ship. The water is $58 \mathrm {~m}$ deep and has an index of refraction of $1.33$ . How far horizontally is the submarine from the side of the ship?
(Assume all numbers are accurate to three significant figures.)

A) $89 \mathrm {~m}$
B) $69 \mathrm {~m}$
C) $79 \mathrm {~m}$
D) $59 \mathrm {~m}$
E) $49 \mathrm {~m}$

Question 67

Write the word or phrase that best completes each statement or answers the question.
A point source of light is positioned $20.0 \mathrm {~m}$ below the surface of a lake. What is the diameter of the largest circle on the surface of the water through which light can emerge into the air? The index of refraction of water is $1.33 .$

Question 68

Choose the one alternative that best completes the statement or answers the question.
An optic fiber is made of clear plastic with an index of refraction of $1.50$ . For what range of angles of incidence $\theta$ with the lateral surface of the fiber will light remain inside the plastic "guide" if it is surrounded by air?

A) $23.4 ^ { \circ } < \theta < 90 ^ { \circ }$
B) $41.8 ^ { \circ } < \theta < 90 ^ { \circ }$
C) $38.3 ^ { \circ } < \theta < 90 ^ { \circ }$
D) $21.1 ^ { \circ } < \theta < 90 ^ { \circ }$
E) $40.3 ^ { \circ } < \theta < 90 ^ { \circ }$

Question 69

Choose the one alternative that best completes the statement or answers the question.
A glass plate with an index of refraction is $1.57$ is immersed in an oil having a refractive index of $1.40$ . The surface of the glass is inclined at an angle of $54 ^ { \circ }$ with the vertical. A horizontal light ray in the glass strikes the interface. What is the angle that the refracted ray, in the oil, makes with the horizontal?

A) $11 ^ { \circ }$
B) $14 ^ { \circ }$
C) $8.3 ^ { \circ }$
D) $17 ^ { \circ }$
E) $5.6 ^ { \circ }$

Question 70

Choose the one alternative that best completes the statement or answers the question.
A light ray in glass arrives at the glass-water interface an an angle of $\theta = 48 ^ { \circ }$ with the normal. The refracted ray in water makes an angle $\phi = 72 ^ { \circ }$ angle with the normal, as shown in the figure. The index of refraction of water is $1.33$ . The angle of incidence is now changed to $\theta = 37 ^ { \circ }$ . What is the new angle of refraction $\phi$ in the water?

A) $46 ^ { \circ }$
B) $52 ^ { \circ }$
C) $48 ^ { \circ }$
D) $54 ^ { \circ }$
E) $50 ^ { \circ }$

Question 71

Choose the one alternative that best completes the statement or answers the question.
A beam of light traveling in air strikes a slab of transparent material. The incident beam makes an angle of $40 ^ { \circ }$ with the normal, and the refracted beam make an angle of $26 ^ { \circ }$ with the normal. What is the speed of light in the transparent material? $\left( c = 3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } \right)$

A) $1.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$
B) $2.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$
C) $3.0 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$
D) $0.50 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$
E) $2.3 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s }$

Question 72

Write the word or phrase that best completes each statement or answers the question.
A ray of light traveling in air makes a $63.0 ^ { \circ }$ angle with respect to the normal of the surface of a liquid. It travels in the liquid at a $39.2 ^ { \circ }$ angle with respect to the normal. Find the critical angle for total internal reflection for this interface.

Question 73

Choose the one alternative that best completes the statement or answers the question.
The critical angle for a substance in air is measured at $53.7 ^ { \circ }$ . If light enters this substance from air at $45.0 ^ { \circ }$ with the normal, at what angle with the normal will it continue to travel?

A) $34.7 ^ { \circ }$
B) $53.7 ^ { \circ }$
C) $45.0 ^ { \circ }$
D) It will not continue, but will be totally reflected.

Question 74

Choose the one alternative that best completes the statement or answers the question.
A beam of light in water (of refractive index of $1.33$ ) enters a glass slab (of refractive index $1.50$ ) at an angle of incidence of $60.0 ^ { \circ }$ . What is the angle of refraction in the glass?

A) $90.0 ^ { \circ }$
B) $60.0 ^ { \circ }$
C) $39.8 ^ { \circ }$
D) $50.2 ^ { \circ }$
E) $27.5 ^ { \circ }$

Question 75

Choose the one alternative that best completes the statement or answers the question.
A beam of light in air enters a glass slab with an index of refraction of $1.40$ at an angle of incidence of $30.0 ^ { \circ }$ . What is the angle of refraction?

A) $14.9 ^ { \circ }$
B) $51.8 ^ { \circ }$
C) $30.0 ^ { \circ }$
D) $47.5 ^ { \circ }$
E) $20.9 ^ { \circ }$

Question 76

Choose the one alternative that best completes the statement or answers the question.
Lucite has an index of refraction of $1.50$ . What is its critical angle if it is in air?

A) $65.2 ^ { \circ }$
B) $15 ^ { \circ }$
C) $41.8 ^ { \circ }$
D) $1.16 ^ { \circ }$
E) $87.4 ^ { \circ }$

Question 77

Write the word or phrase that best completes each statement or answers the question.
A thick slab of plastic lies at the bottom of a tank filled with water having an index of refraction of 1.33. A narrow laser beam is shone directly downward through the water on the plastic. You then gradually rotate the laser, thereby increasing the angle with respect to the normal that it strikes the plastic. You carefully note that at the instant the beam makes an angle of $66.5 ^ { \circ }$ with the normal in the water, no light enters the plastic, but it did enter for angles smaller than that. What is the speed of light in the plastic slab? $\left( c = 3.00 \times 10 ^ { 8 } \right.$ $\mathrm { m } / \mathrm { s }$ )

Question 78

Choose the one alternative that best completes the statement or answers the question.
A thin flashlight beam traveling in air strikes a glass plate at an angle of $52 ^ { \circ }$ with the plane of the surface of the plate. If the index of refraction of the glass is $1.4$ , what angle will the beam make with the normal in the glass?

A) $26 ^ { \circ }$
B) $38 ^ { \circ }$
C) $56 ^ { \circ }$
D) $34 ^ { \circ }$
E) $64 ^ { \circ }$

Question 79

Choose the one alternative that best completes the statement or answers the question.
A light ray in air strikes a glass plate whose index of refraction is $1.42$ . Some of the light reflects off the surface of the plate, but most of it enters the glass. If the angle of refraction is one-half the angle of reflection, the angle of refraction is closest to which one of the following angles?

A) $37 ^ { \circ }$
B) $41 ^ { \circ }$
C) $43 ^ { \circ }$
D) $39 ^ { \circ }$
E) $45 ^ { \circ }$

Question 80

Choose the one alternative that best completes the statement or answers the question.
A light ray in glass arrives at the glass-water interface at an angle of $\theta = 48 ^ { \circ }$ with the normal. The refracted ray in water makes an angle $\theta = 61 ^ { \circ }$ with the normal, as shown in the figure. The index of refraction of water is $1.33$ . The angle of incidence is now changed to $\theta = 25 ^ { \circ }$ . What is the new angle of refraction $\phi$ in the water?

A) $62 ^ { \circ }$
B) $30 ^ { \circ }$
C) $60 ^ { \circ }$
D) $56 ^ { \circ }$
E) $54 ^ { \circ }$