Deck 18: Ray Optics

Question 1

Light having a frequency in vacuum of 6.0 × 10¹⁴ Hz enters a liquid of refractive index 2.0.In this liquid,its frequency will be:

A)12 × 10¹⁴ Hz
B)6.0 × 10¹⁴ Hz
C)3.0 × 10¹⁴ Hz
D)1.5 × 10¹⁴ Hz
E)None of the above choices are correct.

Answer 1

6.0 × 10¹⁴ Hz

Question 2

A ray in glass is incident onto a water-glass interface,at an angle of incidence equal to half the critical angle for that interface.The indices of refraction for water and the glass are 1.33 and 1.43,respectively.The angle that the refracted ray in the water makes with the normal is closest to:

A)37°
B)42°
C)47°
D)32°
E)27°

Answer 2

37°

Question 3

A glass plate whose index of refraction is 1.57 is immersed in a liquid.The surface of the glass is inclined at an angle of 54° with the vertical.A horizontal ray in the glass is incident on the interface.The liquid is an oil whose index of refraction is 1.40.The incident horizontal ray refracts at the interface.The angle that the refracted ray,in the oil,makes with the horizontal is closest to:

A)11°
B)5.6°
C)8.3°
D)14°
E)17°

Answer 3

11°

Question 4

A drop of unknown liquid is placed at the point on a glass surface where internal reflection is occurring at θ = 48°.The drop is heated until internal reflection occurs.What is the refractive index of the liquid if n_g = 1.60?

A)1.19
B)2.38
C)1.07
D)0.46

Question 5

The speed of light in a material is 0.41 c.What is the critical angle of a light ray at the interface between the material and a vacuum?

A)24°
B)17°
C)19°
D)22°

Question 6

A ray in glass arrives at the glass-water interface at an angle of 48° with the normal.The refracted ray,in water,makes a 62° angle with the normal.The index of refraction of water is 1.33.In the figure,the angle of incidence of a different ray in the glass is 25°.The angle of refraction in the water is closest to:

A)57°
B)55°
C)53°
D)59°
E)61°

Question 7

A light ray (red)enters a concentrically cladded optical fiber at its center and an angle of 29.0° to the axis of the fiber.The diameter of the fiber is 1.0 mm and its refractive index is nf = 1.35.What must be the value of ncladding to guarantee total internal reflection? (n_air = 1.00)

A)1.18
B)1.26
C)1.70
D)1.08

Question 8

A fisherman in a stream 39 cm deep looks downward into the water and sees a rock on the stream bed.How deep does the stream appear to the fisherman? Assume that the index of refraction of the water is 1.33.

A)29 cm
B)52 cm
C)33 cm
D)45 cm

Question 9

The index of refraction of the core of a piece of fiber optic cable is 1.72.If the index of the surrounding cladding is 1.41,what is the critical angle for total internal reflection for a light ray in the core incident on the core-cladding interface?

A)55.1°
B)44.0°
C)49.6°
D)60.6°

Question 10

A ray in glass arrives at the glass-water interface at an angle of 48° with the normal.The refracted ray,in water,makes a 68° angle with the normal.The index of refraction of water is 1.33.In the figure,the angle of incidence of a different ray in the glass is 29°.The angle of refraction in the water is closest to:

A)37°
B)35°
C)33°
D)39°
E)41°

Question 11

A tank holds a layer of oil,1.70 m thick,which floats on a layer of syrup that is 0.74 m thick.Both liquids are clear and do not intermix.A ray,which originates at the bottom of the tank on a vertical axis,crosses the oil-syrup interface at a point 0.90 m from the axis.The ray continues and arrives at the oil-air interface,2.00 m from the axis and at the critical angle.In the figure,the index of refraction of the oil is closest to:

A)1.84
B)1.82
C)1.80
D)1.86
E)1.88

Question 12

Light having a speed in vacuum of 3.0 × 10⁸ m/s enters a liquid of refractive index 2.0.In this liquid,its speed will be:

A)6.0 × 10⁸ m/s
B)3.0 × 10⁸ m/s
C)1.5 × 10⁸ m/s
D)0.75 × 10⁸ m/s
E)None of the above choices are correct.

Question 13

Two plane mirrors make an angle of 30°.A light ray enters the system and is reflected once off each mirror.Through what angle is the ray turned?

A)60°
B)90°
C)120°
D)150°

Question 14

A fish appears to be 2.00 m below the surface of a pond when viewed almost directly above by a fisherman.What is the actual depth of the fish? (n_water = 1.33)

A)2.66 m
B)0.67 m
C)1.5 m
D)0.38 m

Question 15

A ray in air is incident on a glass plate whose index of refraction is 1.42.The angle of refraction is one-half the angle of reflection.The angle of refraction is closest to:

A)45°
B)43°
C)41°
D)39°
E)37°

Question 16

The critical angle for an air-glass interface is 10.9 degrees.A ray in air is incident on the interface.The reflected ray is 100 percent polarized.The angle of refraction is closest to:

A)10.7°
B)10.1°
C)9.51°
D)8.91°
E)8.31°

Question 17

A glass plate whose index of refraction is 1.66 is immersed in a liquid.The surface of the glass is inclined at an angle of 44° with the vertical.A horizontal ray in the glass is incident on the interface.When the liquid is a certain alcohol,the incident ray arrives at the interface at the critical angle.The index of refraction of the alcohol is closest to:

A)1.15
B)1.13
C)1.11
D)1.09
E)1.17

Question 18

A tank holds a layer of oil,1.58 m thick,which floats on a layer of syrup that is 0.66 m thick.Both liquids are clear and do not intermix.A ray,which originates at the bottom of the tank on a vertical axis,crosses the oil-syrup interface at a point 0.90 m from the axis.The ray continues and arrives at the oil-air interface,2.00 m from the axis and at the critical angle.In the figure,the index of refraction of the syrup is closest to:

A)1.24
B)1.17
C)1.66
D)1.52
E)1.37

Question 19

Light having a wavelength in vacuum of 600 nm enters a liquid of refractive index 2.0.In this liquid,its wavelength will be:

A)1200 nm
B)600 nm
C)300 nm
D)150 nm
E)None of the above choices are correct.

Question 20

A cylindrical tank is 50.0 ft deep,37.5 ft in diameter,and filled to the top with water.A flashlight shines into the tank from above.What minimum angle φ can its beam make with the water surface if the beam is to illuminate part of the bottom? (nwater = 1.33)

A)37.1°
B)42.4°
C)47.3°
D)30.9°

Question 21

Situation 18.2
An erect object is 50 cm from a concave mirror of radius 60 cm.
In Situation 18.2,the character of the image is:

A)real and erect
B)real and inverted
C)virtual and erect
D)virtual and inverted
E)indeterminate

Question 22

Situation 18.2
An erect object is 50 cm from a concave mirror of radius 60 cm.
In Situation 18.2,the object is moved to a new position,such that the new lateral magnification is +2.5.The new object distance,in cm,is closest to:

A)18
B)24
C)30
D)36
E)42

Question 23

If an object is inside the focal point of a converging lens,this lens always produces a virtual image of that object;but if the object is outside the focal point,the lens always produces a real image.

Question 24

What experiment could you quickly do to detect the difference between a real diamond and an identically shaped fake?

Question 25

In the figure,in the investigation of a new type of optical fiber (index of refraction n = 1.26),a laser beam is incident on the flat end of a straight fiber in air.What is the maximum angle of incidence θ₁ if the beam is not to escape from the fiber?

A)50.0°
B)46.9°
C)43.8°
D)40.7°
E)37.6°

Question 26

For both diverging and converging lenses,a ray parallel to the optical axis refracts through the far focal point.

Question 27

Situation 18.1
A tank holds a 1.44 m thick layer of oil that floats on a 0.96 m thick layer of brine.Both liquids are clear and do not intermix.Point O is at the bottom of the tank,on a vertical axis.The indices of refraction of the oil and the brine are 1.40 and 1.52,respectively.
In Situation 18.1,a ray originating at O,crosses the brine-oil interface at a point 0.60 m from the axis.The ray continues and emerges into the air.The angle that the ray in the air makes with the vertical is closest to:

A)48°
B)51°
C)54°
D)57°
E)60°

Question 28

Light goes from medium A into medium B.If you measure that the angle the rays make with the normal in A is less than the angle they make with the normal in B,then you can conclude that the refractive index of A is less than the refractive index of B.

Question 29

Situation 18.2
An erect object is 50 cm from a concave mirror of radius 60 cm.
In Situation 18.2,the lateral magnification of the image is closest to:

A)+0.4
B)+0.7
C)+1.5
D)-0.7
E)-1.5

Question 30

A concave spherical mirror has a focal length f.The image of an object located at a distance s > f in front of the mirror is real and inverted.

Question 31

Situation 18.1
A tank holds a 1.44 m thick layer of oil that floats on a 0.96 m thick layer of brine.Both liquids are clear and do not intermix.Point O is at the bottom of the tank,on a vertical axis.The indices of refraction of the oil and the brine are 1.40 and 1.52,respectively.
In Situation 18.1,a ray originating at O reaches a point on the oil-air interface at the critical angle.The distance of this point from the axis is closest to:

A)1.5 m
B)1.7 m
C)1.9 m
D)2.1 m
E)2.3 m

Question 32

Situation 18.1
A tank holds a 1.44 m thick layer of oil that floats on a 0.96 m thick layer of brine.Both liquids are clear and do not intermix.Point O is at the bottom of the tank,on a vertical axis.The indices of refraction of the oil and the brine are 1.40 and 1.52,respectively.
In Situation 18.1,a ray originating at O reaches a point on the brine-oil interface at the critical angle.The distance of this point from the axis is closest to:

A)1.5 m
B)1.7 m
C)1.9 m
D)2.1 m
E)2.3 m

Question 33

A single diverging lens always produces a virtual image of an object.

Question 34

In general,the more strongly curved a lens's surface,the lower its index of refraction.

Question 35

Total internal reflection can occur only when light passes from a material of high refractive index to one of low refractive index,never the other way around.

Question 36

Situation 18.2
An erect object is 50 cm from a concave mirror of radius 60 cm.
In Situation 18.2,the distance of the image from the mirror,in cm,is closest to:

A)19
B)35
C)60
D)75
E)120

Question 37

A virtual image will not show up on a screen,and it cannot be photographed.

Question 38

Describe the operation of a one-way mirror.Is there actually such an optical element?

Question 39

The critical angle for two materials is the angle of incidence for which the incident light is not deflected as it passes from one of these materials into the other one.

Question 40

If a lens produces a magnification of 1/4,the image is 4 times a large as the object but is inverted.

Question 41

A screen and a converging lens of focal length f are arranged to have an image of the moon fall on the screen.What is the distance between the lens and the screen?

A)infinity
B)f
C)2f
D)f/2

Question 42

You move a lens from your eye to arm's length away and a far scene never becomes inverted.What can you say about the focal length?

Question 43

If a single lens forms a virtual image of an object,then

A)the lens must be a diverging lens.
B)the lens must be a converging lens.
C)the lens could be either a diverging or a converging lens.
D)the image must be inverted.

Question 44

If you increase the object distance from 4 to 8,what happen to the amount of light admitted through the lens? What happens to the real image?

Question 45

Suppose you place your face in front of a concave mirror.

A)If you position yourself between the center of curvature and the focal point of the mirror,you will not be able to see your image.
B)No matter where you place yourself,a real image will be formed.
C)Your image will always be inverted.
D)Your image will be diminished in size.
E)None of these is true.

Question 46

When moving a convex lens toward and away from your eye it reaches a point where the entire lens appears a single color.What is this point? Why?

Question 47

A flashlight forms a 10 ft spot on a far wall.How can you tell if the filament is between the focal point and the spherical reflector or outside of it?

Question 48

In old spy movies diamonds are hidden in a bottle of water or vodka.Would this really work?

Question 49

Suppose you wanted to start a fire using sunlight and a mirror.Which of the following statements is most accurate?

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

Question 50

You have several concave mirrors.What quick test could you make to choose the one with the best figure? (i.e. ,the most constant curvature)?

Question 51

If an object is placed outside the focal point of a converging lens,the image is

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

Question 52

As you walk away from a plane mirror on a wall,your image

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

Question 53

Which statement about thin lenses is correct? In each case,we are considering only a single lens.

A)A converging lens always produces a real inverted image.
B)A diverging lens always produces a virtual inverted image.
C)A converging lens sometimes produces a real erect image.
D)A diverging lens always produces a virtual erect image.
E)A diverging lens produces a virtual erect image only if the object is located within the focal point of the lens.

Question 54

Which statement about images is correct?

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

Question 55

Why shouldn't you spray water on your roses at noon?

Question 56

A person of height h stands in front of a plane mirror.What is the minimum length of the mirror such that he can see his entire body?

A)h
B)h/2
C)2h
D)h/4
E)It depends on how far the person is from the mirror.

Question 57

An object placed to the left of a lens and its focal point forms an image at d.When placed at the focal point the image is formed at infinity (d = ∞).When it is placed between the focal point and the lens it is formed at d > ∞.Explain.

Question 58

If an object is placed inside the focal point of a diverging lens,the image is

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