PHYS 1320 Chapter 28 HW – Flashcards

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

Light travels from one place to another along a path of least A) expense. B) complication. C) effort. D) time. E) distance.

Fermat's principle could be the principle of least distance for A) reflection. B) refraction. C) both of these D) neither of these

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

The amount of light reflected from the front surface of a common windowpane is about A) 40%. B) 96%. C) 8%. D) 4%. E) 92%.

Your image in a plane mirror is A) virtual. B) real. C) both of these D) neither of these

When light reflects from a surface, there is a change in its A) wavelength. B) frequency. C) speed. D) all of the above E) none of the above

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

The shortest plane mirror in which you can see your entire image is A) equal to your height. B) about 1/3 your height. C) half your height. D) dependent on your distance from the mirror. E) about 3/4 your height.

If you look at yourself in a pocket mirror, then hold the mirror farther away, you see A) more of yourself. B) the same amount of yourself. C) less of yourself.

It is difficult to see the roadway when driving on a rainy night mainly because A) the film of water on the roadway makes the road less diffuse. 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) light scatters from raindrops and reduces the amount of light reaching your eyes. E) none of the above

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

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

Refraction occurs when light passing from one medium to another A) changes frequency. B) reflects inward. C) changes speed. D) loses energy.

Light refracts when traveling from air into glass because of a change in light's A) frequency. B) intensity. C) speed. D) all of the above E) none of the above

When a light ray in air enters water at 15° from the normal, it A) always bends toward the normal. B) sometimes bends towards or away from the normal. C) does not bend. D) always bends away from the normal.

When light passes through common windowpane, its angle of emergence is A) the same as its angle of incidence. B) usually more than its angle of incidence. C) usually less than its angle of incidence. D) always less than its angle of incidence. E) always more than its angle of incidence.

The twinkling of the stars is a result of atmospheric A) scattering. B) reflection. C) dispersion. D) refraction. E) aberrations.

The average speed of light is greatest in A) green glass. B) blue glass. C) red glass. D) orange glass. E) same in all of these

Atmospheric refraction makes the daylight hours a bit A) shorter. B) longer in summer but shorter in winter. C) longer.

A fish above the surface of water will see better in air if it has goggles that are A) extremely shiny. B) filled with water. C) tinted blue. D) hemispherical. E) none of the above

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

Stephanie dips a glass rod into vegetable oil. The submerged part of the rod can't be seen because A) light has different speeds in the oil and glass. B) both the oil and glass have the same index of refraction. C) of internal reflection. D) refraction is unbent before light gets to your eye.

To "spear" a red fish with a red laser beam and compensate for refraction, aim your laser A) above the sighted fish. B) directly at the sighted fish. C) below the sighted fish.

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.

A person who sees more clearly under water without eyeglasses or a facemask is A) farsighted. B) nearsighted. C) neither of these

When a colored light in air shines on water and is refracted, its wavelength A) lengthens. B) remains unchanged. C) shortens.

The Moon's redness during a lunar eclipse is due to A) light of lower frequencies reflected from the Moon. B) an optical illusion. C) excess infrared radiation. D) refracted light from Earth's sunrises and sunsets. E) none of the above

Light of different colors in a vacuum travel at A) the same speed. B) the same speed in both a vacuum and all materials. C) different speeds.

Which are consequences of different speeds of light in different media? A) brilliant colors of diamonds B) rainbows C) mirages D) all of the above E) none of the above

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

A mirage occurs for road surfaces that are most often A) hard. B) cold. C) hot. D) snowy. E) wet.

Rainbows exist because light is A) refracted. B) reflected. C) both of these D) neither of these

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

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

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.

When you are beneath the surface of water and looking upward, light from above is seen A) at any angle if the surface is smooth. B) within a cone of 96°. C) at angles beyond a cone of 96°.

When a light beam emerges from water into air, light speed A) remains the same. B) increases. C) decreases.

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

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) more than 15°. C) 15°. D) impossible to predict.

In optical fibers of uniform density, light actually A) curves in a direction parallel to the central axis of the fiber. B) travels along the outer surface of the fiber. C) travels in straight-line segments. D) none of the above

The type of lens that spreads parallel light is a A) diverging lens. B) converging lens. C) combination of converging-diverging lens.

Which of the following can be projected onto a viewing screen? A) a real image B) a virtual image C) both of these D) neither of these

Your vision is sharpest when your pupil is A) same either way B) constricted. C) dilated.

When the tiny hole in a pinhole camera is made larger, the image is A) right-side up. B) clearer. C) brighter but less clear. D) none of the above

The image of the "infinitely-far-away" Sun produced by a converging lens appears A) beyond the focal point. B) at the focal point. C) between the lens and the focal point.

Magnification by a lens would be greater if light A) traveled faster in glass than it does. B) beams spread less. C) traveled slower in glass than it does. D) propagated instantaneously. E) none of the above

Light travels slower in a lens having a A) low index of refraction. B) high index of refraction. C) same in each

Chromatic aberration is a consequence of different colors in a lens having different A) speeds. B) energies. C) critical angles. D) frequencies. E) aberrations.

An image of the American flag cast by a simple lens finds red and blue colors at slightly different distances from the lens. The color closest to the lens is A) blue. B) red. C) both at the same place

Suppose you walk toward a mirror at 3.0 m/s . How fast do you and your image approach each other? (The answer is not 3.0 m/s .) Express your answer to two significant figures and include the appropriate units.

A butterfly at eye level is 14 cm in front of a plane mirror. You are behind the butterfly, 60 cm from the mirror. What is the distance between your eye and the image of the butterfly in the mirror? Express your answer to two significant figures and include the appropriate units.

When light strikes glass perpendicularly, about 4.4 % is reflected at each surface. Find what percent of light is transmitted through a pane of window glass. Express your answer using two significant figures.

No glass is perfectly transparent. Mainly because of reflections, about 93 % of light passes through an average sheet of clear windowpane. The 7 % 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)? Express your answer using two significant figures.

The diameter of the Sun makes an angle of 0.53∘ from Earth. (A) 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∘.) (B) How does your answer compare with the time it takes the Sun to disappear, once its lower edge meets the horizon at sunset? A) It is the same as the time it takes the Sun to disappear. B) It is the a little shorter than time it takes the Sun to disappear. C) It is the a little longer than time it takes the Sun to disappear. (C) Does refraction affect your answer?