Q&A Hero

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.

Q: 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

Q: 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

Q: If a fish looks upward at 45o 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

Q: 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

Q: 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.

Q: 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.

Q: 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.

Q: 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

Q: When a colored light in air shines on water and is refracted, its frequency A) decreases. B) remains unchanged. C) increases.

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

Q: When light is refracted, there is a change in its A) frequency. B) wavelength. C) both of these D) neither of these

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

Q: 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

Q: 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.

Q: 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.

Q: 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.

Q: 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.

Q: 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.

Q: 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.

Q: 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

Q: 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.

Q: 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

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: A red crab very deep in water, where sunlight is dim, appears A) red. B) orange. C) cyan. D) brown. E) no color"black.

Q: A white boat sunk in water where sunlight is dim appears A) red. B) yellow. C) cyan. D) no color"black.

Q: The extraordinary blueness in lakes in the Canadian Rockies is the result of A) high-altitude refraction of light. B) glacial silt in the water scattering blue light. C) the unique temperatures of these lakes throughout most of the year. D) none of the above

Q: The part of the visible spectrum most absorbed by water is A) infrared. B) red. C) cyan. D) all about equally.

Q: The part of the electromagnetic spectrum most absorbed by water is A) infrared. B) red. C) cyan. D) all about equally.

Q: The greenish blue of water is evidence for the A) reflection of greenish-blue light. B) reflection of red light. C) absorption of greenish-blue light. D) absorption of red light. E) interaction between green and blue frequencies of light.

Q: The darkness of clouds is due to A) absorption. B) often being in the shadow of another cloud. C) both of these D) neither of these