Q&A Hero

Q: 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.

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

Q: In which material does light travel fastest? A) glass B) water C) plastic D) air E) same for all

Q: 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

Q: 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

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

Q: A mirage is a result of atmospheric A) reflection. B) refraction. C) scattering. D) dispersion. E) aberrations.

Q: 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.

Q: When a light ray passes at a non-90o angle from water into air, it A) bends toward the normal. B) bends away from the normal. C) travels much slower.

Q: When a light ray in air enters water at 15o 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.

Q: Light travels fastest in A) warm air. B) cool air. C) a vacuum.

Q: 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

Q: Refraction results from differences in light's A) frequency. B) incident angles. C) speed. D) all of the above E) none of the above

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

Q: 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%

Q: 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%

Q: 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

Q: 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

Q: 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.

Q: 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

Q: 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.

Q: 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.

Q: 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.

Q: 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.

Q: 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

Q: 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

Q: 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

Q: 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

Q: A rough surface for infrared waves may be polished for A) radio waves. B) light waves. C) both of these D) neither of these

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

Q: 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.

Q: 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%.

Q: 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

Q: 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

Q: 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.

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

Q: Fermat's principle applies to A) reflection. B) refraction. C) both of these D) neither of these

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

Q: 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

Q: 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.

Q: If you cover half a camera lens with opaque tape, the images produced will be A) cut in half. B) only dimmer. C) both of these D) neither of these

Q: 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) red. B) blue. C) both at the same place

Q: Chromatic aberration is absent in A) converging lenses B) diverging lenses. C) front surface plane mirrors.

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

Q: When taking a photo of a nearby flower, your camera lens should be set A) closer than one focal length from the photosensitive surface. B) farther than one focal length from the photosensitive surface. C) to one focal length from the photosensitive surface.

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

Q: Magnification is greater with a lens having a A) high index of refraction. B) low index of refraction. C) same in each

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

Q: Sunlight passing through a pinhole in a piece of card casts a solar image on the ground. If the card is held so the image exactly covers a coin, measurements will show you could fit 110 coins between the image and the card. This further tells you A) 110 Suns would fit between the top of the card and the Sun. B) that this activity is useful for estimating the Sun's diameter. C) both of these D) neither of these

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

Q: In a converging lens, objects infinitely far away are focused A) in front of the focal point. B) at the focal point. C) beyond the focal point.

Q: Small openings between leaves in a tree act as pinholes. The round spots of light cast on the ground below are images of A) the Sun. B) the openings themselves. C) both of these D) neither of these

Q: A pinhole cameras has no lens. The tiny pinhole opening insures that rays of light from different parts of an object A) overlap. B) don't overlap. C) bend to a focus.

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

Q: The image in a pinhole camera is A) always inverted. B) sometimes inverted. C) always right-side up.

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

Q: A "burning glass" used to concentrate sunlight in a tiny spot is a A) converging lens. B) diverging lens. C) either of these D) neither of these

Q: 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

Q: The type of lens that brings parallel light rays together is a A) converging lens. B) diverging lens. C) combination of converging-diverging lens.

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

Q: Optical fibers are commonly used by A) surgeons. B) mechanics. C) engineers. D) aviators. E) all of the above

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

Q: The refraction of light in a diamond is greater for A) long-wavelength light. B) short-wavelength light. C) both refract the same

Q: At night an underwater scuba diver aims a flashlight beam toward the surface at 15o to the normal. Upon emerging into the air, the beam angle will be A) less than 15o. B) 15o. C) more than 15o. D) impossible to predict.

Q: If a fish in a pond looks upward at 50o 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

Q: A diver shines light upward to the surface of a smooth pond at 20o 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 20o. B) 20o. C) more than 20o. D) all refracts, none reflects.

Q: The critical angle is least in A) glass. B) water. C) diamond. D) vacuum.

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

Q: 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

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

Q: 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.

Q: 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.

Q: 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

Q: 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.

Q: 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.

Q: 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.

Q: 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.

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

Q: 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

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