Deck 28: Reflection and Refraction

Question 1

Fermat's principle could be the principle of least distance for

A)reflection.
B)refraction.
C)both of these
D)neither of these

Answer 1

reflection.

Question 2

If you look at yourself in a pocket mirror, then hold the mirror farther away, you see

A)more of yourself.
B)less of yourself.
C)the same amount of yourself.

Answer 2

the same amount of yourself.

Question 3

A rough surface for infrared waves may be polished for

A)radio waves.
B)light waves.
C)both of these
D)neither of these

Answer 3

radio waves.

Question 4

Object and image for a plane mirror occur

A)along the same plane.
B)equal distances from the mirror.
C)at right angles to each other.
D)all of the above
E)none of the above

Question 5

The amount of light reflected from the front surface of a common windowpane is about

A)4%.
B)8%.
C)40%.
D)92%.
E)96%.

Question 6

Fermat's principle applies to

A)reflection.
B)refraction.
C)both of these
D)neither of these

Question 7

If you walk towards a mirror at a certain speed, the relative speed between you and your image is

A)half your speed.
B)your speed.
C)twice your speed.
D)none of the above

Question 8

Light travels from one place to another along a path of least

A)distance.
B)time.
C)effort.
D)expense.
E)complication.

Question 9

Diffuse reflection occurs when the size of surface irregularities is

A)small compared to the wavelength of the light used.
B)large compared to the wavelength of the light used.
C)microscopic.

Question 10

When light reflects from a surface, there is a change in its

A)frequency.
B)wavelength.
C)speed.
D)all of the above
E)none of the above

Question 11

When sunlight illuminates a page from your Conceptual Physics book it

A)reflects most of it.
B)absorbs at the text lettering.
C)both of these
D)neither of these

Question 12

You photograph the image of your little sister, who stands 2 meters in front of a plane mirror. Holding the camera beside her head, the distance to her image is

A)1 meter.
B)2 meters.
C)3 meters.
D)4 meters.
E)none of the above

Question 13

Your image in a plane mirror is

A)virtual.
B)real.
C)both of these
D)neither of these

Question 14

Light is reflected when

A)electron clouds of atoms are energized.
B)atomic nuclei are made to vibrate.
C)incident light is returned into the medium from which it came.
D)electromagnetic waves emanate from matter.

Question 15

The shortest plane mirror in which you can see your entire image is

A)half your height.
B)about 3/4 your height.
C)about 1/3 your height.
D)equal to your height.
E)dependent on your distance from the mirror.

Question 16

According to the law of reflection, the incident light ray, the reflected light ray, and the normal between them

A)lie in the same plane.
B)may or may not lie in the same plane.
C)lie in planes that are perpendicular to one another.

Question 17

A yellow candle flame reflects from opposite surfaces of a piece of red glass.

A)both images are yellow
B)one image is yellow and the other red
C)both images are red
D)both images are reddish yellow

Question 18

The inversion of your image in a plane mirror is actually an inversion of

A)left-right.
B)up-down.
C)front-back.
D)all of the above

Question 19

In looking at yourself in a steamy mirror you wipe just enough moisture away to barely see a full view of your face. If you move back from the mirror you'll see

A)a bit more of your face.
B)a bit less of your face.
C)the same amount of your face.

Question 20

To see his full height, Blinky Bill who is 1 meter tall needs a mirror that is at least

A)0.33 m tall.
B)0.50 m tall.
C)0.75 m tall.
D)1 m tall.
E)depends on distance from the mirror.

Question 21

When a mirror with a fixed beam on it is rotated through a certain angle, the reflected beam is rotated through an angle that is

A)equal to the angle of rotation.
B)twice as large.
C)four times as large.
D)none of these

Question 22

When a light ray passes at a non-90° angle from water into air, it

A)bends toward the normal.
B)bends away from the normal.
C)travels much slower.

Question 23

The twinkling of the stars is a result of atmospheric

A)reflection.
B)refraction.
C)scattering.
D)dispersion.
E)aberrations.

Question 24

Ninety percent of light incident on a certain piece of glass passes through it. How much light passes through two pieces of this glass?

A)80%
B)81%
C)85%
D)89%
E)90%

Question 25

When light passes through common windowpane, its angle of emergence is

A)usually less than its angle of incidence.
B)always less than its angle of incidence.
C)the same as its angle of incidence.
D)usually more than its angle of incidence.
E)always more than its angle of incidence.

Question 26

The average speed of light is greatest in

A)red glass.
B)orange glass.
C)green glass.
D)blue glass.
E)same in all of these

Question 27

Refraction results from differences in light's

A)frequency.
B)incident angles.
C)speed.
D)all of the above
E)none of the above

Question 28

In which material does light travel fastest?

A)glass
B)water
C)plastic
D)air
E)same for all

Question 29

When a light ray in air enters water at 15° from the normal, it

A)always bends toward the normal.
B)always bends away from the normal.
C)sometimes bends towards or away from the normal.
D)does not bend.

Question 30

Light travels fastest in

A)warm air.
B)cool air.
C)a vacuum.

Question 31

Refraction causes the bottom of a swimming pool to appear

A)farther down than it actually is.
B)closer to the surface than it actually is.
C)neither of these

Question 32

Refraction occurs when light passing from one medium to another

A)changes frequency.
B)changes speed.
C)loses energy.
D)reflects inward.

Question 33

It is difficult to see the roadway when driving on a rainy night mainly because

A)light scatters from raindrops and reduces the amount of light reaching your eyes.
B)of additional condensation on the inner surface of the windshield.
C)the film of water on your windshield provides an additional reflecting surface.
D)the film of water on the roadway makes the road less diffuse.
E)none of the above

Question 34

Atmospheric refraction makes the daylight hours a bit

A)longer.
B)shorter.
C)longer in summer but shorter in winter.

Question 35

Ninety-five percent of light incident on a mirror is reflected. How much light is reflected when three of these mirrors are arranged so light reflects from one after the other?

A)81%
B)85%
C)86%
D)90%
E)95%

Question 36

Standing at the shore of a still lake, the reflected view of scenery on the other side of the lake is the view you would see if you were upside down with your eye in the line of sight

A)where it already is.
B)at the surface of the water where the light reflects.
C)directly beneath you, as far below water level as you are above.
D)close to the distant shore.
E)none of the above

Question 37

Reflected light from the Moon in a lake often appears as a vertical column when the water is

A)perfectly still.
B)slightly rough.
C)very rough as with churning waves.

Question 38

A mirage is a result of atmospheric

A)reflection.
B)refraction.
C)scattering.
D)dispersion.
E)aberrations.

Question 39

When a pulse of white light is incident on a glass prism, the first color to emerge is

A)red.
B)orange.
C)green.
D)violet.

Question 40

Light refracts when traveling from air into glass because of a change in light's

A)intensity.
B)frequency.
C)speed.
D)all of the above
E)none of the above

Question 41

Light of different colors in a glass prism travel at

A)different speeds.
B)the same speed.
C)the same speed in prisms and all materials.

Question 42

When spearing a fish with a regular spear, to compensate for refraction, throw your spear

A)directly at the sighted fish.
B)above the sighted fish.
C)below the sighted fish.

Question 43

If a fish looks upward at 45° to a pond's water's surface, it will see

A)the pond's bottom.
B)the sky and possibly some tall surroundings.
C)only the water's surface.
D)none of the above

Question 44

The index of refraction for crown glass, common in eyeglasses, is 1.52. The index of refraction of a particular plastic lens is 1.76. Light bends more in the

A)crown glass.
B)plastic lens.
C)same speed in each.
D)need more information

Question 45

To "spear" a red fish with a red laser beam and compensate for refraction, aim your laser

A)directly at the sighted fish.
B)above the sighted fish.
C)below the sighted fish.

Question 46

A person standing waist-deep in a swimming pool appears to have short legs because of light

A)reflection.
B)absorption.
C)interference.
D)diffraction.
E)refraction.

Question 47

Stars twinkle when seen from Earth. When seen by an astronaut on the Moon, stars

A)twinkle more.
B)twinkle less.
C)don't twinkle.

Question 48

Stephanie dips a glass rod into vegetable oil. The submerged part of the rod can't be seen because

A)refraction is unbent before light gets to your eye.
B)both the oil and glass have the same index of refraction.
C)of internal reflection.
D)light has different speeds in the oil and glass.

Question 49

To "spear" a blue fish with a red laser beam and compensate for refraction, aim your laser

A)directly at the sighted fish.
B)above the sighted fish.
C)below the sighted fish.

Question 50

When a colored light in air shines on water and is refracted, its frequency

A)decreases.
B)remains unchanged.
C)increases.

Question 51

When a colored light in air shines on water and is refracted, its wavelength

A)shortens.
B)remains unchanged.
C)lengthens.

Question 52

Which are consequences of different speeds of light in different media?

A)mirages
B)rainbows
C)brilliant colors of diamonds
D)all of the above
E)none of the above

Question 53

When light is refracted, there is a change in its

A)frequency.
B)wavelength.
C)both of these
D)neither of these

Question 54

The Sun's elliptical shape at sunset can be adequately explained by

A)Fermat's principle.
B)the law of refraction.
C)both of these
D)neither of these

Question 55

A fish above the surface of water will see better in air if it has goggles that are

A)tinted blue.
B)hemispherical.
C)filled with water.
D)extremely shiny.
E)none of the above

Question 56

The Moon's redness during a lunar eclipse is due to

A)light of lower frequencies reflected from the Moon.
B)excess infrared radiation.
C)an optical illusion.
D)refracted light from Earth's sunrises and sunsets.
E)none of the above

Question 57

Light of different colors in a vacuum travel at

A)different speeds.
B)the same speed.
C)the same speed in both a vacuum and all materials.

Question 58

To send a beam laser-light beam to a space station just above the atmosphere near the horizon, aim your laser

A)above your line of sight.
B)below your line of sight.
C)along your line of sight.

Question 59

A person who sees more clearly under water without eyeglasses or a facemask is

A)nearsighted.
B)farsighted.
C)neither of these

Question 60

If the speed of light in a sphere is 2 × 10⁸ m/s, its index of refraction is

A)0.50.
B)0.67.
C)1.0.
D)1.5.
E)2.0.

Question 61

If a fish in a pond looks upward at 50° to the normal, it will see

A)the pond's bottom.
B)the sky and possibly some tall surroundings.
C)only the water's surface.
D)none of the above

Question 62

A single raindrop illuminated by sunshine disperses

A)a single color.
B)mainly light of mid-frequency colors.
C)all the colors of the rainbow.

Question 63

The secondary rainbow is dimmer than the primary rainbow mainly because

A)its colors are inverted.
B)it is larger, and its energy is spread over more area.
C)it is farther from the viewer.
D)it simply has less energy than the primary bow.
E)of an extra reflection and refraction in the drops.

Question 64

Rainbows are not usually seen as complete circles because

A)the ground is usually in the way.
B)they are actually elliptical.
C)they have no bottom part.
D)rain drops are not perfectly round.
E)rainbows are actually arched shaped.

Question 65

When you are beneath the surface of water and looking upward, light from above is seen

A)within a cone of 96°.
B)at angles beyond a cone of 96°.
C)at any angle if the surface is smooth.

Question 66

When a light beam emerges from water into air, light speed

A)increases.
B)decreases.
C)remains the same.

Question 67

If you view a rainbow out your window while riding in a train, you'll see that

A)the rainbow can only be seen while you're moving slowly or at rest.
B)the rainbow moves along with you.
C)you soon pass by it, leaving it where you first saw it.

Question 68

At night an underwater scuba diver aims a flashlight beam toward the surface at 15° to the normal. Upon emerging into the air, the beam angle will be

A)less than 15°.
B)15°.
C)more than 15°.
D)impossible to predict.

Question 69

When a rainbow is seen as a complete circle from an airplane, the airplane's shadow is

A)in the center of the rainbow.
B)in the lower part of the rainbow.
C)in the upper part of the rainbow.
D)totally outside the rainbow.
E)nowhere, for there is no shadow.

Question 70

As monochromatic light passes from air to glass and back to air, changes occur in its

A)wavelength.
B)speed.
C)both of these
D)neither of these

Question 71

The refraction of light in a diamond is greater for

A)long-wavelength light.
B)short-wavelength light.
C)both refract the same

Question 72

Rainbows exist because light is

A)reflected.
B)refracted.
C)both of these
D)neither of these

Question 73

When sunlight from air enters water, light that refracts most is

A)red.
B)orange.
C)green.
D)violet.
E)all refract the same amount

Question 74

A mirage occurs when light travels faster

A)near the ground than higher up.
B)in less dense air than more dense air higher up.
C)both of these
D)neither of these

Question 75

Which is a useful property of a prism?

A)internally reflects 100% of incident light
B)changes directions of light in a variety of ways
C)re-inverts images
D)all the above
E)none of the above

Question 76

A diver shines light upward to the surface of a smooth pond at 20° to the normal. Most light passes into the air above while the part that reflects back into the water makes an angle to the normal of

A)less than 20°.
B)20°.
C)more than 20°.
D)all refracts, none reflects.

Question 77

The critical angle for a transparent material is the angle at and beyond which all light within the material at its upper surface is

A)refracted.
B)reflected.
C)absorbed.
D)dispersed.
E)diffused.

Question 78

The critical angle is least in

A)glass.
B)water.
C)diamond.
D)vacuum.

Question 79

A primary rainbow is brighter than a secondary rainbow because

A)sunlight reaching it is more intense.
B)there is one less reflection inside the water drops.
C)larger drops produce primary rainbows.
D)the secondary bow is a dim reflection of the primary rainbow.
E)none of the above

Question 80

A mirage occurs for road surfaces that are most often

A)hot.
B)cold.
C)wet.
D)hard.
E)snowy.