Conceptual Physics

Paul G. Hewitt

Chapter 28

Reflection and Refraction - all with Video Answers

Educators

+ 1 more educators

Chapter Questions

Problem 1

How does incident light that falls on an object affect the motion of electrons in the atoms of the object?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 2

What do the electrons affected by illumination do when they are made to vibrate with greater energy?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 3

What is Fermat’s principle of least time?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 4

Cite the law of reflection.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 5

Relative to the distance of an object in front of a plane mirror, how far behind the mirror is the image?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 6

What fraction of the light shining straight at a piece of clear glass is reflected from the first surface?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 7

Can a surface be considered polished for some waves and not for others? Give an example.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 8

How does the angle at which a ray of light strikes a pane of window glass compare with the angle at which the light passes out the other side?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 9

When is the angle at which a ray of light strikes glass not the same as the angle at which it exits?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 10

In which medium does light travel faster: thin air or dense air? How does this affect the period of daylight?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 11

Does the law of reflection hold for curved mirrors? Explain.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 12

Is a mirage the result of reflection or refraction?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 13

When the wheel of a cart rolls from a smooth sidewalk
onto a plot of grass, the interaction of the wheel with
blades of grass slows the wheel. What slows light when it
passes from air into glass or water?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 14

What is the angle between a light ray and its wavefront?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 15

What is the relationship between refraction and the speed of light?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 16

Are eyeglasses made with “high index of refraction” materials thin or thick?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 17

Does the refraction of light make a swimming pool appear deeper or shallower than it really is?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 18

Which travels more slowly in glass: red light or violet light?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 19

Does a single raindrop illuminated by sunlight deflect light of a single color, or does it disperse a spectrum of colors?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 20

Does a viewer see a single color or a spectrum of colors coming from a single faraway drop?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 21

Why is a secondary rainbow dimmer than a primary bow?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 22

What is meant by “critical angle”?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 23

At what angle inside glass is light totally internally reflected? At what angle inside a diamond is light totally internally reflected?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 24

Light normally travels in straight lines, but it “bends” in an optical fiber. Explain.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 25

Distinguish between a converging lens and a diverging lens.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 26

What is the focal length of a lens?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 27

Distinguish between a virtual image and a real image.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 28

What kind of lens can be used to produce a real image? A virtual image?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 29

Why is vision sharpest when the pupils of the eye are very small?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 30

What is astigmatism, and how can it be corrected?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 31

Plane mirrors and convex mirrors produce virtual images of objects. Can they produce real images under any circumstances? Explain.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 32

You can produce a spectrum by placing a tray of water in
bright sunlight. Lean a pocket mirror against the inside
edge of the tray and adjust it until a spectrum appears
on the wall or ceiling. Aha! You’ve produced a spectrum
without a prism.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 33

Set up two pocket mirrors at right angles and place a
coin between them. You’ll see four coins. Change the
angle of the mirrors and see how many images of the
coin you can see. With the mirrors at right angles, look
at your face. Then wink. Do you see anything unusual?
Hold a printed page up to the double mirrors and
contrast its appearance with the reflection from a single
mirror.

Rashmi Sinha

Numerade Educator

Problem 34

Look at yourself in a pair of mirrors at right angles to each other. You see yourself as others see you. Rotate the mirrors, still at right angles to each other. Does your image rotate also? Now place the mirrors 608 apart so you again see your face. Again rotate the mirrors and see whether your image rotates also. Amazing?

Mayukh Banik

Numerade Educator

Problem 35

Determine the magnifying power of a lens by focusing on the lines of a ruled piece of paper. Count the spaces between the lines that fit into one magnified space, and you have the magnifying power of the lens. You can do the same with binoculars and a distant brick wall. Hold the binoculars so that
only one eye looks at the bricks through the eyepiece while the other eye looks directly at the bricks. The number of bricks seen with the unaided eye that will fit into one magnified brick gives the magnification of the instrument.

Vishal Gupta

Numerade Educator

Problem 36

Poke a hole in a piece of paper, hold it in sunlight so that
the solar image is the same size as a coin on the ground,
and then determine how many coins would fit between the
ground and the pinhole. That’s the same number of solar
diameters that would fit in the distance from Earth to the
Sun. (Do you remember this exercise from Chapter 1?)

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 37

What should be the focal length of reading spectacles for
a person for whom the least distance of distinct vision is
50 cm?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 38

Show with a simple diagram that when a mirror with a
fixed beam incident upon it is rotated through a certain
angle, the reflected beam is rotated through an angle
twice as large. (This doubling of displacement makes
irregularities in ordinary window glass more evident.)

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 39

A butterfly at eye level is 20 cm in front of a plane mirror. You are behind the butterfly, 50 cm from the mirror. What is the distance between your eye and the image of the butterfly in the mirror?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 40

When light strikes glass perpendicularly, about 4$\%$ is reflected at each surface. Show that 92$\%$ of light is transmitted through a pane of window glass.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 41

No glass is perfectly transparent. Mainly because of
reflections, about 92$\%$ of light passes through an average
sheet of clear windowpane. The 8$\%$ loss is not noticed
through a single sheet, but through several sheets, the
loss is apparent. How much light is transmitted by a
double-paned window (one with two sheets of glass)?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 42

The diameter of the Sun makes an angle of $0.53^{\circ}$ from
Earth. How many minutes does it take the Sun to move
1 solar diameter in an overhead sky? (Remember that it
takes 24 hours, or 1440 minutes, for the Sun to move
through $360^{\circ} .$ ) How does your answer compare with the
time it takes the Sun to disappear, once its lower edge
meets the horizon at sunset? (Does refraction affect your
answer?)

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 43

She looks at her face in the handheld mirror. Rank the
amounts of her face that she sees in the three locations,
from greatest to least (or is it the same in
all positions?).

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 44

Wheels from a toy cart are rolled from a concrete sidewalk onto the following surfaces: A, a paved driveway; B, a grass lawn; and C, close-cropped grass on a golf-course putting green. Due to slowing, each set of wheels bends at the boundary and is deflected from its initial straightline course. Rank the surfaces according to the amount each set of wheels bends at the boundary, from greatest amount of bending to least.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 45

Identical rays of light enter three transparent blocks composed of different materials. Light slows down
upon entering the blocks. Rank the blocks according to the speed light travels in each, from highest
to lowest.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 46

Identical rays of light in air are refracted upon entering
three transparent materials: A, water, where the speed of
light is $0.75 c ; \mathrm{B}$ , ethyl alcohol (speed $0.7 c ) ;$ and $\mathrm{C}$ , crown
glass $(\text { speed } 0.6 c) .$ Rank the materials according to how
much the light ray bends toward the normal, from most
bending to least bending.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 47

This chapter opened with a photo of physics instructor
Peter Hopkinson seeming to hover above the table. He
isn’t. Explain how he creates this illusion.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 48

In the opening photo of the duck standing on the rock, why aren’t the duck’s feet shown in the reflected view?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 49

In the opening photo of physics teacher Fred Myers taking a photo of his daughter McKenzie, how many mirrors were involved? Explain.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 50

In the multiple images of physics teacher Karen Jo Matsler in the opening photo, how many mirrors are
involved?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 51

Fermat’s principle is of least time rather than of least distance. Would least distance apply as well
for reflection? For refraction? Why are your answers different?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 52

Her eye at point P looks into the mirror. Which of the numbered cards can she see reflected in the mirror?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 53

Cowboy Joe wishes to shoot his assailant by ricocheting a bullet off a mirrored metal plate. To do so, should he simply aim at the mirrored image of his assailant? Explain.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 54

Why is the lettering on the front of some vehicles “backward”?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 55

Trucks often have signs on their back ends that say, “If you can’t see my mirrors, I can’t see you.” Explain the physics here.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 56

When you look at yourself in the mirror and wave your
right hand, your beautiful image waves the left hand.
Then why don’t the feet of your image wiggle when you
shake your head?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 57

Car mirrors are uncoated on the front surface and silvered on the back surface. When the mirror is properly adjusted, light from behind reflects from the silvered surface into the driver’s eyes. Good. But this is not so good at nighttime with the glare of headlights behind. This problem is solved by the wedge shape of the mirror (see the sketch). When the mirror is tilted slightly upward to the “nighttime” position, glare is directed upward toward the ceiling, away from the driver’s eyes. Yet the driver can
still see cars behind in the mirror. Explain.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 58

A person in a dark room looking through a window
can clearly see a person outside in the daylight, whereas
the person outside cannot see the person inside.
Explain.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 59

What is the advantage of having matte (nonglossy) pages
in this book rather than pages with a glossier surface?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 60

What must be the minimum length of a plane mirror in order for you to see a full image of yourself?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 61

What effect does your distance from the plane mirror have in your answer to the preceding exercise? (Try it and see!)

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 62

Hold a pocket mirror almost at arm’s length from your face and note how much of your face you can see. To see more of your face, should you hold the mirror closer or farther away, or would you have to have a larger mirror? (Try it and see!)

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 63

On a steamy mirror, wipe away just enough to see your full face. How tall will the wiped area be compared with the vertical dimension of your face?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 64

The sketch shows a person and her twin at equal distances on opposite sides of a thin wall. Suppose a window is to be cut into the wall so that each twin can see a complete view of the other. Show the size and location of the smallest window that can be cut into the wall to do the job. (Hint: Draw rays from the top of each twin’s head to the other twin’s eyes. Do the same from the feet of each to the eyes of the other.)

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 65

You can tell whether people are nearsighted or farsighted by looking at the size of their eyes through their glasses. When a person’s eyes seem magnified, is the person nearsighted or farsighted?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 66

If a nearsighted person wants thinner eyeglasses, is a higher or a lower index of refraction for the lenses
recommended?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 67

Your friend says that the wavelength of light waves is shorter in water than in air and cites Figure 28.25 as evidence. Do you agree or disagree, and why?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 68

A pair of toy cart wheels is rolled obliquely from a
smooth surface onto two plots of grass, a rectangular
plot and a triangular plot, as shown. The ground is on a
slight incline so that, after slowing down in the grass, the
wheels will speed up again when emerging on the smooth
surface. Finish each sketch by showing some positions of
the wheels inside the plots and on the other sides, thereby
indicating the direction of travel.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 69

A pulse of red light and a pulse of blue light enter a glass
block at the same time normal to its surface. Strictly
speaking, after passing through the block, which pulse
exits first?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 70

During a lunar eclipse, the Moon is not completely
dark but is usually deep red. Explain this in terms of
the refraction of all the sunsets and sunrises around the
world.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 71

What accounts for the large shadows cast by the ends of the thin legs of the water strider?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 72

When you stand with your back to the Sun, you see a
rainbow as a circular arc. Could you move off to one side
and then see the rainbow as the segment of an ellipse
rather than the segment of a circle (as Figure 28.33
suggests)? Defend your answer.

Prashant Bana

Numerade Educator

Problem 73

Why will goggles allow a swimmer under water to focus more clearly on what he or she is looking at?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 74

If a fish wore goggles above the water surface, why would the fish’s vision be better if the goggles were filled with water? Explain.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 75

Does a diamond under water sparkle more or less than in air? Defend your answer.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 76

Cover the top half of a camera lens. What effect does this have on the pictures taken?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 77

What will happen to the image projected onto a screen
by a lens when you cover one-third of the lens with a red
filter, one-third with a green filter, and one-third with a
blue filter? (Try it and see!)

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 78

How could a converging lens be made for sound waves?
(Such a lens, a spherical bag of gas, is a feature of San
Francisco’s Exploratorium.)

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 79

Would refracting telescopes and microscopes magnify if light had the same speed in glass as in air? Defend your answer.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 80

There is less difference between the speed of light in
glass and the speed of light in water than there is between
the speed of light in glass and the speed of light in air.
Does this mean that a magnifying glass will magnify
more or magnify less when it is used under water rather
than in air?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 81

Waves don’t overlap in the image of a pinhole camera. Does this feature contribute to a sharp image or to a blurry image?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 82

Why doesn’t the sharpness of the image in a pinhole camera depend on the position of the viewing screen?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 83

Whereas pinholes provide sharp images, lenses with large apertures are advantageous for spy cameras of high-flying aircraft. Why?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 84

If you point the pinhole camera of question 82 at the Sun, a clear and bright solar image will be seen on the viewing screen. How does this relate to the circular spots of light that surround Lillian beneath the sunlit tree shown in the photo?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 85

In terms of focal length, how far behind the camera lens
is a photosensitive surface located when very distant
objects are being photographed?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 86

Why do you put slides into an old-fashioned slide projector upside down?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 87

The image produced by a converging lens is upside
down. Our eyes have converging lenses. Does this mean
the images we see are upside down on our retinas?
Explain.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 88

The images produced by a converging camera lens are
upside down. Does this mean the photographs taken
with cameras are upside down?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 89

Maps of the Moon are upside down. Why?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 90

Why do older people who do not wear glasses read books farther away from their eyes than younger
people do?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 91

When Stephanie Hewitt dips a glass rod into vegetable
oil, the submerged part of the rod is invisible. What does
this say about the relative speeds of light in the glass and
in the oil? Or asked another way, how do the indices of
refraction, n, compare for the glass and oil?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 92

To reduce glare from the surroundings, the windows
of some department stores, rather than being vertical,
slant inward at the bottom. Discuss why this reduces
glare.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 93

Which kind of road surface is easier to see when driving
at night: a pebbled, uneven surface or a mirror-smooth
surface? Discuss why is it difficult to see the roadway in
front of you when driving on a rainy night.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 94

Why does reflected light from the Sun or Moon appear as a column in the body of water as shown? How would the reflected light appear if the water surface were perfectly smooth?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 95

What exactly are you seeing when you observe a “water on the road” mirage?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 96

What is wrong with the cartoon of the man looking at himself in the mirror? (Have a friend face a mirror as shown, and you’ll see.)

Keshav Singh

Numerade Educator

Problem 97

A beam of light bends as shown in (a), while the edges of the immersed square bend as shown in (b). Do these pictures contradict each other? Explain.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 98

When a flashlight submerged in water shines up into
the air above, does the speed of light increase or decrease
when the light passes from water into the air?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 99

If, while standing on a riverbank, you wish to spear a
fish beneath the water surface in front of you, should
you aim above, below, or directly at the observed fish
to make a direct hit? If, instead, you zap the fish with
a laser, should you aim above, below, or directly at the
observed fish? Defend your answers.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 100

If the fish in the preceding exercise were small and blue
and your laser light were red, what corrections should
you make? Explain.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 101

When a fish in a pond looks upward at an angle of 45°, does it see the sky above the water’s surface or a reflection from the water–air boundary of the bottom of the pond? Defend your answer.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 102

Rays of light moving upward through water toward the water-air boundary at angles larger than $48^{\circ}$ to the normal are totally reflected. No rays larger than $48^{\circ}$ refract
outside. How about the reverse? Is there an angle at which light rays in air meeting the air-water boundary will totally reflect? Or will some light be refracted at all angles?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 103

If you were to send a beam of laser light to a space station above the atmosphere that appears just above the horizon, would you aim the laser above, below, or at the visible space station? Defend your answer.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 104

Two observers standing apart from each other do not see the “same” rainbow. Explain.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 105

A rainbow viewed from an airplane may form a complete circle. Where will the shadow of the airplane appear? Explain.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 106

How is a rainbow similar to the halo sometimes seen around the Moon on a frosty night? If you’re stumped, check the Internet and see how rainbows and halos differ.

Ajay Singhal

Numerade Educator

Problem 107

Transparent plastic swimming-pool covers called solar heat sheets have thousands of small air-filled bubbles that resemble lenses. The bubbles in these sheets are advertised to focus heat from the Sun into the water, thereby raising its temperature. Do you think these bubbles direct more solar energy into the water? Defend your answer.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 108

Would the average intensity of sunlight measured by a light meter at the bottom of the pool in Figure 28.46 be different if the water were still?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 109

When your eye is submerged in water, light rays bend
only slightly when they pass from the water into your
cornea. Why isn’t the bending as pronounced as when
light passes from air into your cornea? (How do the
indices of refraction differ for your cornea, air, and
water?)

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 110

When your eye is submerged in water, does the speed of
light increase, decrease, or remain constant as it passes
from the water into your cornea?

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator

Problem 111

Two rays are shown in the sketch that accompanies
footnote 3, repeated here. Discuss whether these two
rays produce the image or merely locate where the image
is in relation to the lens.

Sri Datta Vikas Buchemmavari

Sri Datta Vikas Buchemmavari

Numerade Educator