Light and Telescopes Test Bank Chapter 3 - Discovering the Universe 14e Test Bank + Answers by Neil F. Comins. DOCX document preview.
Chapter 3: Light and Telescopes
Section: 3-1
1. When visible light passes through a prism of glass, as shown in Figure 3-1, which wavelengths of light are deflected MOST by the glass?
A) longer wavelengths
B) intermediate wavelengths, the green color
C) All wavelengths are deviated by the same amount.
D) shorter wavelengths
2. When light passes through a prism of glass,
A) the prism absorbs colors from different parts of the broad beam coming out of the prism, leaving the complementary colors seen.
B) different colors are caused by multiple reflections within the prism and the resulting interference between the beams.
C) refraction changes the directions of different colors or wavelengths of light.
D) the prism adds colors to different parts of the outgoing and broadly scattered beam.
3. Isaac Newton’s prism experiment showed that when a beam of white light passes through a prism, the prism
A) adds color to the light.
B) subtracts from the light to allow the previously masked colors to appear.
C) changes the white light into something completely different so that it could not be reformed into white light.
D) causes different colors in the white light to be emitted in different directions.
4. If one sends white light through a prism to produce a spectrum, and then sends the red part of that spectrum through a second prism, the result will be
A) red.
B) yellow.
C) white.
D) black (no light).
5. If one sends white light through a prism to produce a spectrum, and then sends this entire spectrum through a lens to recombine it, the result will be
A) red.
B) yellow.
C) white.
D) black (no light).
6. When white light passes through a prism a spectrum is formed. This is because the prism
A) adds color to the light.
B) subtracts from the light, producing color.
C) causes different wavelengths of light to travel in different directions.
D) causes different parts of the light beam to vibrate at different frequencies.
7. In 1670, Isaac Newton performed a crucial experiment on the nature of light when he
A) proved mathematically that light could be described by oscillating electric and magnetic fields.
B) demonstrated that white light was made up of colors that could be split by a prism and that these colors were not produced by the glass through which the light passed.
C) showed that a prism through which light passed added a spectrum of colors to the light.
D) demonstrated the wave nature of light by passing light through two slits and obtaining a pattern of bright and dark bands on a screen that he ascribed to interference between the two beams.
8. In 1801, Thomas Young performed a crucial experiment on the nature of light when he
A) demonstrated the wave nature of light by passing light through two slits and obtained a pattern of bright and dark bands on a screen that he correctly interpreted as interference between the two light beams.
B) proved mathematically that light could be described by oscillating electric and magnetic fields.
C) showed that a prism through which light passed added a spectrum of colors to the light.
D) demonstrated that white light was made up of colors that could be split by a prism and that these colors were not produced by the glass through which the light passed.
9. Thomas Young demonstrated that light behaves as a wave by showing that
A) light striking a metal surface releases electrons from the metal, with violet light producing more energetic electrons than red light.
B) light passing through two narrow, closely spaced slits produces a pattern of light and dark bands on a screen by wave interference.
C) the speed of light in a vacuum is the same for all observers.
D) the speed of light decreases when it enters a denser, transparent medium.
10. In his double-slit experiment, Thomas Young used just a single color of light. Suppose he had used a mixture of two colors. What result would he have obtained?
A) The two waves would have canceled each other out, and he would have seen nothing. This is why he used only one color.
B) Two patterns would have formed, one on each color, exactly on top of each other.
C) Two similar patterns would have formed with the light of the shorter wavelength forming the more closely spaced pattern.
D) Two similar patterns would have formed with the light of the longer wavelength forming the more closely spaced pattern.
11. In the 1860s, James Clerk Maxwell carried out important investigations on the nature of light when he
A) demonstrated the wave nature of light by passing light through two slits and obtained a pattern of bright and dark bands on a screen that he correctly interpreted as interference between the two light beams.
B) demonstrated that white light was made up of colors that could be split by a prism and that these colors were not produced by the glass through which the light passed.
C) proved mathematically that light could be described by oscillating electric and magnetic fields.
D) showed that a prism through which light passed added a spectrum of colors to the light.
12. Who first proved that light is a wave?
A) Albert Einstein
B) Thomas Young
C) Isaac Newton
D) James Clerk Maxwell
13. Who was the first person to suggest that light is an electromagnetic wave?
A) Thomas Young
B) Isaac Newton
C) Albert Einstein
D) James Clerk Maxwell
14. In the seventeenth century, Isaac Newton suggested a particle theory for light and Christian Huygens proposed a wave theory. The present understanding is that
A) the wave theory is correct; the particle theory is not.
B) the particle theory is correct; the wave theory is not.
C) neither theory provides a correct description of light.
D) a combination of both theories is necessary to provide a correct description of light.
15. Electromagnetic radiation moving through space with the speed of light consists of oscillating
A) electric and magnetic fields moving in opposite directions along the same line in space.
B) magnetic fields that over time and distance change to oscillating electric fields and then back to magnetic fields in a continuous manner.
C) electric and magnetic fields with the same frequency and wavelength and traveling in the same direction.
D) electric fields, with magnetic fields occasionally accompanying them, moving in the same direction.
16. One nanometer (nm) is
A) 10–12 m.
B) 10–6 m.
C) 109 m.
D) 10–9 m.
17. Visible wavelengths of electromagnetic radiation have a range of wavelengths of
A) 400 nm to 700 nm.
B) 1 nm to 100 nm.
C) 800 nm to 1900 nm.
D) 90 nm to 130 nm.
18. In angstroms (Ǻ), the visible wavelengths of electromagnetic radiation have a range of
A) 40 Ǻ to 70 Ǻ.
B) 400 Ǻ to 700 Ǻ.
C) 4000 Ǻ to 7000 Ǻ.
D) 40,000 Ǻ to 70,000 Ǻ.
19. Which wavelength region of the electromagnetic spectrum is taken up by visible light?
A) 1200 nm to 1500 nm
B) 4000 nm to 7000 nm
C) 400 nm to 700 nm
D) 100 nm to 400 nm
20. The wavelength of green light is about 500 nanometers. What is this length in meters?
A) 500 thousandths of a meter
B) 500 trillionths of a meter (1 trillion = 1,000,000 million)
C) 500 millionths of a meter
D) 500 billionths of a meter (1 billion = 1000 million)
21. Violet light differs from red light in that it
A) travels more quickly (through a vacuum) than red light.
B) has a shorter wavelength than red light.
C) travels more slowly (through a vacuum) than red light.
D) has a longer wavelength than red light.
22. One difference between violet light and red light is that
A) violet light travels faster than red light, even in a vacuum.
B) violet light has a shorter wavelength than red light.
C) violet light is hotter than red light.
D) photons of violet light have less energy than photons of red light.
23. What is the relationship between color and wavelength for light?
A) Wavelength increases from violet to yellow-green, then decreases again to red.
B) Wavelength decreases from violet to red.
C) Wavelength increases from violet to red.
D) Wavelength depends only on brightness and is independent of color.
24. All forms of light have what property in common?
A) All forms of light are electromagnetic radiation.
B) All forms of light have the same wavelength.
C) All forms of light are ultrasonic radiation.
D) All forms of light have wavelengths between 400 nm and 700 nm.
Section: 3-2
25. The speed of light is
A) 3 × 1010 m/sec.
B) 3 ×108 m/sec.
C) 3 ×1012 m/sec.
D) 3 ×105 m/sec.
26. Approximately how long does it take light to travel from the fingertips of a person’s extended arm to one’s eye?
A) zero time because light is transmitted instantaneously
B) 2.5 trillionths of a second (2.5 × 10–12 sec)
C) 2.5 billionths of a second (2.5 nanoseconds)
D) 2.5 millionths of a second (2.5 microseconds)
27. If a laser light pulse was sent toward the Moon and some of this light were to be reflected toward Earth from retroreflectors left on the Moon by astronauts, how long after the transmission of the initial flash would the reflected light be detected through a telescope on Earth?
A) 2.56 microseconds
B) 2.56 seconds
C) 1.28 seconds
D) 1.28 milliseconds
28. Who first showed that light does not travel at infinite speed, and when did they show it?
A) Ole Rømer in 1675
B) Thomas Young in 1801
C) James Clerk Maxwell in 1864
D) Isaac Newton in 1704
29. Which method did Ole Rømer use to show that light did not travel at infinite speed?
A) Rømer observed that eclipses of Jupiter’s satellites by the planet appeared to occur later when Earth was farther away from Jupiter because of the travel time for light over the extra distance.
B) Rømer measured a time delay between the instant that he sent a flash of light to a mirror on a distant hill and the return of the flash after reflection.
C) Rømer carried out a laboratory experiment in which a light beam was sent through an opaque, rotating disk with holes in it and reflected from a distant mirror, where the returning beam did not return through the same hole from which it left because of the travel time for light.
D) Rømer measured a 2
-second delay between the time of the outgoing pulse of light sent from Earth to the Moon and the time of the returning light pulse after reflection from the Moon.
30. In 1675, Ole Rømer measured the speed of light by
A) timing eclipses of Jupiter’s satellites by the planet, which appeared to occur later when Earth was farther from Jupiter.
B) opening a shutter on a lantern on a hilltop and measuring the time taken for light from an assistant’s shuttered lantern to return.
C) reflecting light from a mirror rotating at a known speed and measuring the angle of deflection of the light beam.
D) measuring how long it took the light to reach Earth from stars located at different distances from Earth.
31. What prevented Ole Rømer from calculating an accurate value for the speed of light from his measurements of the delays in eclipse times of Jupiter’s moons?
A) The dimensions of the solar system, particularly the length of 1 au, were not known very accurately.
B) Telescopes were not good enough at that time to show Jupiter’s moons clearly, and accurate timings were not possible.
C) The distance between Earth’s orbit and Jupiter’s orbit was unknown.
D) The clocks available at that time were not sufficiently accurate.
32. How much time elapsed from when Ole Rømer discovered that light did not travel at infinite speed to a time when the speed of light was first measured accurately?
A) No time at all—it was Rømer himself who measured this speed accurately!
B) 28 years
C) almost 1000 years
D) more than a century but less than two centuries
33. Suppose one tries to explain Rømer’s measurements in the Ptolemaic model (adding the Galilean moons) with circular orbits and Earth in the center of the system. How could the differences in eclipse times be explained?
A) The later times would still occur when Jupiter is at conjunction and the earlier times when Jupiter is at opposition.
B) The later times would occur when Jupiter is moving westward with respect to the stars and the earlier times when Jupiter is moving eastward with respect to the stars.
C) The later times would occur when Jupiter is moving eastward with respect to the stars and the earlier times when Jupiter is moving westward with respect to the stars.
D) Jupiter in this model is the same distance from Earth at all times so no explanation is possible.
34. The speed of light in space is
A) infinite, traveling through space instantaneously.
B) variable, depending on the speed of its source, but very large (on average, 3 × 108 meters per second).
C) 3 × 1010 meters per second, independent of the speed of the source.
D) 3 ×108 meters per second, independent of the speed of the source.
35. Suppose Rømer had used Saturn and one of its satellites instead of Jupiter and Io to measure the speed of light. How would his measurements have compared with those for Jupiter?
A) The measured time discrepancy between predicted and measured values for a given eclipse would have been shorter for Saturn.
B) The measured time discrepancy between predicted and measured values for a given eclipse would have been the same for Saturn.
C) The measured time discrepancy between predicted and measured values for a given eclipse would have been longer for Saturn.
D) Rømer could not have made such a measurement because Saturn had not yet been discovered.
36. The diameter of Earth is about 13,000 km. What distance does light travel in one second, in terms of the diameter of Earth?
A) 23 times the diameter
B) 23,077 times the diameter
C) 46 times the diameter
D) 0.043 times the diameter
37. When the Galileo spacecraft reached Jupiter on December 7, 1995, Jupiter was almost at conjunction with the Sun. Given that it takes 8 1/3 minutes for light to travel a distance of 1 au, how long did it take Galileo’s signals to reach Earth from Jupiter? (A diagram might help to envision this configuration.)
A) 52 minutes
B) 35 minutes
C) 60 minutes
D) 43 minutes
38. The average distance of Pluto from the Sun is 40 au. How long does it take for light to travel across the solar system from one side of Pluto’s orbit to the other?
A) 5 ½ hours
B) 8 minutes
C) 22 hours
D) 11 hours
39. Suppose Ole Rømer had been able to make accurate speed-of-light measurements from the eclipses of Saturn’s satellites as well as Jupiter’s. How would these measurements have compared?
A) Calculations from the Saturn data should produce a larger value for the speed of light.
B) Calculations from the Saturn data should produce a smaller value for the speed of light.
C) The times for the Saturn eclipses should show larger discrepancies from the predicted values, but the calculated speed of light should be the same.
D) The times for the Saturn eclipses should show smaller discrepancies from the predicted values, but the calculated speed of light should be the same.
Section: 3-3
40. Consider a beam of electromagnetic radiation of a single frequency. The energy of each photon in this beam depends on each these properties of the beam EXCEPT
A) wavelength.
B) frequency.
C) intensity.
D) color.
41.
41. In which these parameters does a photon of blue light NOT differ from a photon of yellow light in a vacuum?
A) energy
B) color
C) wavelength
D) speed
42. In which one of these ranges of the electromagnetic spectrum do photons have the MOST energy?
A) infrared
B) visible
C) ultraviolet
D) All of them since all electromagnetic photons have the same energy.
43. A particular photon of ultraviolet (UV) light has a wavelength of 200 nm and a photon of infrared (IR) light has a wavelength of 2000 nm. What is the energy of the UV photon compared to that of the IR photon?
A) The UV photon has 1/10 of the energy of the IR photon.
B) The UV photon has 10 times more energy than the IR photon.
C) The UV photon has 1/100 of the energy of the IR photon.
D) The UV photon has 100 times more energy than the IR photon.
44. If two photons in a vacuum have different energies, what can be said about the wavelengths of the photons?
A) The higher-energy photon has the shorter wavelength.
B) The higher-energy photon has the longer wavelength.
C) The two photons have the same wavelength; all photons have the same wavelength, regardless of energy.
D) We cannot say anything; wavelength depends only on color, not on energy.
45. A particular photon has a wavelength of 450 nm, and a second one has a wavelength of 580 nm. Which of these statements about the energies of these two photons is true?
A) All photons have the same energy, regardless of wavelength.
B) The 450-nm photon has the higher energy.
C) The 580-nm photon has the higher energy.
D) The photon from the higher-intensity light source has the higher energy (regardless of wavelength).
46. The idea that light consists of photons, bundles of pure energy, was first proposed by
A) Newton.
B) Rømer.
C) Young.
D) Einstein.
47. In the photoelectric effect, a beam of light impinges on a metal, and it is observed that electrons are ejected from the metal in greater numbers as the
A) wavelength of the light is increased.
B) wavelength of the light is decreased.
C) intensity of the light is increased.
D) intensity of the light is decreased.
48. Our present understanding of the nature of light is that it
A) behaves only as a wave.
B) behaves only as a particle.
C) displays behavior of both waves and particles.
D) is completely different from both waves and particles.
49. A beam of light of which of these pure colors is made up of photons of the lowest energy?
A) red
B) yellow
C) green
D) blue
50. A beam of light of which of these pure colors is made up of photons of the highest energy?
A) red
B) yellow
C) green
D) blue
51. The radio station has a broadcast frequency of 89.7 megahertz. What is the energy of a single photon in this radio beam (in joules)?
A) 1.03 × 10–31
B) 5.98 × 10–26
C) 4.95 × 10–22
D) 2.86 × 10–19
52. What is 3 × 108 m/s divided by 500 nm?
A) 6 × 105 meters per second
B) 6 × 1014 per second
C) 6 × 107 meters per nanometer
D) 6 × 1014 meters per second
Section: 3-4
53. The Lyman-alpha spectral line of hydrogen has a wavelength of 121.6 nm. In which wavelength band does this line occur?
A) ultraviolet
B) visible light
C) Infrared
D) X-ray
54. What is the one fundamental difference between X-rays and radio waves?
A) X-rays and radio waves can only be produced by different sources.
B) The wavelengths of X-rays and radio waves are very different.
C) The speeds of X-rays and radio waves in outer space are different.
D) Radio waves are wavelike, whereas X-rays only behave like particles.
55. Which of these sequences of electromagnetic radiation is correct, in order of increasing energy of the photons (or quanta)?
A) visible light, microwave, radio wave, infrared
B) radio wave, microwave, gamma ray, UV
C) visible light, UV radiation, X-ray, gamma ray
D) gamma ray, radio wave, X-rays, infrared
56. In the 1860s, Maxwell derived a set of mathematical equations that described electromagnetic waves that could have different wavelengths. These waves, which include visible light, have since been shown to
A) have no wavelength limit, either short or long.
B) have no upper wavelength limit, but waves cannot exist with wavelengths smaller than an atom.
C) have no short wavelength limit, but waves cannot exist with wavelengths longer than about the diameter of Earth.
D) exist only over a wavelength range from infrared to ultraviolet radiation.
57. Visible light occupies what portion of the full wavelength range of electromagnetic radiation?
A) a very narrow range
B) two narrow but separate ranges between ultraviolet and infrared radiations, the red and the blue, which mix to give all the other colors
C) about half of the possible range
D) almost the full range between radio and X-ray
58. The wavelength of infrared radiation is longer than the wavelength of visible light and is usually measured in units of micrometers. 1 micrometer (m) is
A) 10–6 m.
B) 10–3 m.
C) 106 m.
D) 10–9 m.
59. How does the wavelength of visible light compare to the wavelengths of other forms of electromagnetic radiation?
A) longer than ultraviolet but shorter than X-ray
B) longer than X-ray but shorter than gamma ray
C) longer than infrared but shorter than radio wave
D) longer than X-ray but shorter than radio wave
60. Visible light occupies what position in the electromagnetic spectrum?
A) between radio and infrared radiation
B) between infrared and ultraviolet
C) between infrared and microwave
D) between ultraviolet and X-ray
61. Which of these statements is true?
A) Visible light takes up only a very small part of the total range of wavelengths in the electromagnetic spectrum.
B) Visible light takes up the whole electromagnetic spectrum.
C) Visible light takes up most (but not all) of the total range of wavelengths in the electromagnetic spectrum.
D) Visible light is not part of the electromagnetic spectrum.
62. Which of these lists of different types of electromagnetic radiation is correctly ordered in wavelength, from shortest to longest?
A) gamma ray, ultraviolet, radio, infrared
B) radio, ultraviolet, infrared, gamma ray
C) radio, infrared, ultraviolet, gamma ray
D) gamma ray, ultraviolet, infrared, radio
63. Which of these types of electromagnetic radiation has the longest wavelength?
A) radio wave
B) ultraviolet light
C) infrared
D) microwave
64. Which of these types of electromagnetic radiation has the shortest wavelength?
A) visible light
B) X-ray
C) ultraviolet
D) gamma ray
65. In terms of wavelengths, gamma rays
A) have the shortest wavelengths of the named electromagnetic waves.
B) are intermediate, between X-rays and ultraviolet waves.
C) are intermediate, between radio and infrared waves.
D) have the longest wavelengths of the named electromagnetic waves.
66. Which of these wave effects is electromagnetic?
A) gravitational wave
B) cosmic ray proton
C) microwave
D) sound wave
67. Which of these wave effects is NOT electromagnetic in nature?
A) gamma rays
B) seismic waves
C) microwaves
D) radio waves
68. Electromagnetic radiation emitted by a planet has a wavelength of 10 micrometers (1 m = 10–6 m). What name is given to this type of electromagnetic radiation?
A) gamma ray
B) infrared
C) radio
D) visible light
69. Suppose an astronomical satellite observes the Orion Nebula at a wavelength of 1250 nm. In what wavelength range is this satellite observing?
A) X-ray
B) ultraviolet
C) infrared
D) visible light
70. Suppose an astronomical satellite observes the Crab Nebula at a wavelength of 0.85 nm. In what wavelength range is this satellite observing?
A) X-ray
B) ultraviolet
C) Infrared
D) gamma ray
71. X-rays and visible light are
A) different because X- rays are made up of waves, whereas light is made up of particles.
B) different because X-rays are made up of particles, whereas light is made up of waves.
C) the same thing except that X-rays have longer wavelengths than visible light.
D) the same thing except that X-rays have shorter wavelengths than visible light.
72. Radio waves travel through space at what speed?
A) much faster than the speed of light
B) at the speed of light, 3 × 108 m/s
C) much slower than the speed of light
D) slightly faster than the speed of light because their wavelength is longer
73. Which of these can travel at the speed of light in a vacuum?
A) visible light, radio waves, X-rays, and gamma rays
B) only visible light; all other electromagnetic waves travel slower than the speed of light.
C) visible light, atoms, X-rays, and subatomic particles (e.g., electrons)
D) visible light, infrared radiation, ultraviolet radiation, and subatomic particles (e.g., electrons)
74. An electrical spark, such as lightning, generates electromagnetic radiation over a wide range of wavelengths. How much longer will a pulse of radio energy take to travel between two detector stations 100 m apart than will a pulse of ultraviolet radiation from the same spark?
A) The time will be identical because both pulses travel at the speed of light.
B) Just a little longer because the high frequency UV radiation travels faster than the low frequency radio waves.
C) A much shorter time because long wavelength radiation travels faster.
D) A much longer time because radio waves have much longer wavelengths and therefore travel slower.
75. The two ranges of electromagnetic radiation for which Earth’s atmosphere is reasonably transparent are
A) X- ray and visible light.
B) visible light and radio wave.
C) visible light and far infrared radiation.
D) UV radiation and radio wave.
76. Earth’s atmosphere is transparent to which of these types of electromagnetic radiations?
A) X-ray
B) radio wave
C) long infrared wavelength
D) short ultraviolet wavelength
77. Which of these wavelength regions must be observed from space because almost no energy in this region reaches the ground?
A) radio
B) infrared
C) X-rays
D) visible light
78. An electromagnetic wave has a wavelength of 80 cm. This wave is
A) visible light.
B) ultraviolet radiation.
C) infrared radiation.
D) a radio wave.
79. If a person creates a spectrum with a prism as Newton did and then probes the temperature with thermometers that they have kept in the dark, they will find the thermometer will show a temperature rise when placed
A) in the visible part of the spectrum but nowhere else.
B) in the visible part of the spectrum and in the invisible region just beyond the red but nowhere else.
C) in the visible part of the spectrum and in the invisible region just beyond the violet but nowhere else.
D) anywhere from the invisible region beyond the red, through the visible, through the invisible region beyond the violet.
Section: 3-5
80. Who was one of the first astronomers to build and use a telescope to observe the night sky?
A) Galileo
B) Copernicus
C) Tycho Brahe
D) Newton
81. Astronomers sometimes choose the type of reflecting telescope to use as a result of the amount of strain the weight of the mounted equipment will exert on the telescope. Which type of reflector generally results in the MOST strain?
A) Cassegrain focus
B) Newtonian focus
C) prime focus
D) coudé focus
82. One advantage of using a Cassegrain telescope is that
A) larger mirrors can be used with a Cassegrain telescope than with a Newtonian telescope of similar size.
B) Cassegrain telescopes use spherical mirrors, which are easier to manufacture than the parabolic mirrors required by other telescopes.
C) Cassegrain telescopes have holes cut out of their primary mirrors to make them lighter.
D) observing equipment mounted on a Cassegrain telescope is more balanced and stable than if it were mounted on a Newtonian telescope.
83. Research observatories do NOT use Newtonian reflectors because they
A) cannot be made large enough for modern astronomical work.
B) are inherently lopsided and cannot support heavy research instruments.
C) are more sensitive to atmospheric distortions than are refractors.
D) require two mirrors, whereas the Cassegrain requires only one.
84. When a ray of light strikes a smooth mirror surface at an angle to the perpendicular, the ray is reflected
A) on the “other” side of the perpendicular but at the same angle as the incoming ray.
B) in reverse along its original (incoming) path.
C) at various angles, depending on wavelength.
D) so that it travels along the perpendicular to the surface of the mirror.
85. Who developed the first reflecting astronomical telescope?
A) Ptolemy
B) Isaac Newton
C) Galileo
D) Copernicus
86. A Newtonian telescope uses
A) only one mirror with its front surface shaped into a parabola.
B) one curved mirror and one flat mirror at a 45° angle to the first mirror axis.
C) two flat mirrors inclined to each other at a right angle.
D) two curved mirrors, one convex, the second concave in shape.
87. Which of these optical elements or combinations make up a Newtonian telescope?
A) two curved mirrors, one concave, the second convex
B) two lenses, to produce an image the correct way around
C) one concave and one flat mirror
D) one concave focusing mirror
88. Compared to the direction of the incoming light, in which way does the light leave the eyepiece of a Newtonian telescope?
A) at a variable angle depending on the direction of the source in the sky
B) in the same direction
C) in the reverse direction, back toward the source
D) at right angles
89. A Newtonian reflecting telescope is constructed using a
A) concave primary mirror and a flat, diagonal secondary mirror.
B) concave primary mirror and a concave secondary mirror that reflects light through a hole in the primary mirror.
C) concave primary mirror and a convex secondary mirror that reflects light through a hole in the primary mirror.
D) convex primary mirror and a flat, diagonal mirror mounted at 45° to the primary mirror.
90. The prime focus of a reflecting telescope is reached by light after
A) one reflection.
B) refraction through one lens and reflection at one mirror.
C) reflection at two mirrors.
D) refraction at one lens.
91. A Cassegrain reflecting telescope is constructed using a
A) concave primary mirror followed by a smaller convex secondary mirror that reflects light back through a hole in the primary mirror.
B) curved primary mirror followed by a series of both plane and curved mirrors that channel the light to a remote location fixed with respect to Earth.
C) concave primary mirror and concave secondary mirror that reflects light back through a hole in the primary mirror.
D) concave primary mirror and a flat, diagonal secondary mirror mounted at a 45° angle to the telescope axis.
92. When light from the concave primary mirror of a telescope is reflected by a small secondary mirror through a hole in the primary to its focus, it is called the
A) Cassegrain focus.
B) Newtonian focus.
C) coudé focus.
D) prime focus.
93. A particular telescope is set up to use the coudé focus. Which arrangement of mirrors is used to bring the light to this focus?
A) curved primary mirror followed by a series of plane and curved mirrors that channel the light to a remote and fixed location
B) concave primary mirror followed by a convex secondary mirror that reflects light through a hole in the primary mirror
C) concave primary mirror followed by a concave secondary mirror that reflects light through a hole in the primary mirror
D) concave primary mirror and a flat, diagonal secondary mirror mounted at a 45° angle to the telescope axis
94. Light from a pointlike light source will enter a person’s detector almost parallel if the source is very far away. If one moves closer to the source, the light entering one’s detector
A) becomes more parallel.
B) becomes more divergent (the rays move away from each other).
C) becomes more convergent (the rays move toward each other).
D) remains unchanged.
Section: 3-6
95. Some research telescopes have secondary mirrors that block the central part of the larger primary mirror. What problem does this introduce for observations?
A) Because the secondary mirror blocks part of the primary, there is a hole in the center of the resulting image.
B) Because the secondary mirror diverts light away from the original path, it distorts the image.
C) Because the secondary mirror blocks part of the primary, the image is darker.
D) There is no disadvantage to this arrangement.
96. Placing a secondary mirror in front of the primary mirror
A) creates a blank spot in the image.
B) darkens the image.
C) brightens the image due to increased reflection.
D) causes problems that must be corrected by using a Schmidt corrector plate.
97. Light from each part of the source being observed falls on each part of the primary mirror of a Newtonian telescope not obstructed by the secondary mirror. The important consequence of this is that
A) the image does not have a dark spot indicating the presence of the secondary mirror.
B) the image is not darkened (overall) because of the presence of the secondary mirror.
C) cheaper spherical mirrors can be used rather than a more costly parabolic mirror.
D) the secondary mirror can be made as large as needed without influencing the quality of the image.
Section: 3-7
98. The major reason astronomers seek funds to build larger telescopes is to
A) measure a wider spectrum of light from stars.
B) collect more light from distant objects.
C) provide magnified images of stars.
D) bring stars closer to Earth.
99. The main reason for building larger optical telescopes on Earth’s surface is to
A) bring astronomical objects closer for more detailed examination by scientists.
B) collect more light from faint objects.
C) enhance national prestige, with no scientific reason.
D) nullify the effects of Earth’s atmosphere and thus produce higher resolution photographs.
100. The light-gathering power of a telescope depends directly on the
A) area of the final aperture of its eyepiece.
B) focal length of its primary mirror or lens.
C) ratio of the focal lengths of its primary element (mirror or lens) and its eyepiece.
D) area of its primary mirror or lens.
101. What is the magnification of a Newtonian telescope that has a primary mirror of diameter 0.25 m and focal length of 2 m when used with an eyepiece of focal length 25 mm and an optical diameter of 5 mm?
A) 50 times
B) 10 times
C) 80 times
D) 400 times
102. Many amateur astronomers have telescopes with mirrors 20 cm (1/5 m) in diameter. In comparison, one of the largest astronomical telescopes in the world is the Keck telescope, with a diameter of 10 m. How much greater is the light-gathering power of the Keck telescope than the power of a 20-cm telescope?
A) 50 times greater
B) 7 times greater
C) 125,000 times greater
D) 2500 times greater
103. For many years, the Palomar telescope (5-m diameter) in California was the largest telescope in the world; it has now been surpassed by a number of facilities, including both the Keck I and Keck II telescopes (each of diameter 10 m) in Hawaii. How much greater is the light-gathering power of a Keck telescope than that of the Palomar telescope?
A) 4 times greater
B) 8 times greater
C) 2 times greater
D) 1.4 times greater
104. Compared with the 2.5-m diameter Mount Wilson telescope, each of the 10-m diameter Keck telescopes has a greater light-gathering power by a factor of
A) 4.
B) 16.
C) 2.
D) 1; they have the same light-gathering capability.
105. How many times more light will be collected by the optics of one side of a pair of binoculars (7 × 50—magnification of 7 and an objective lens aperture diameter of 50 mm) than by an average human eye, with a typical aperture diameter of 5 mm?
A) 100 times
B) 10 times
C) 2500 times
D) 7/5, or 1.4 times
106. How much more light can the 5-m telescope at Mount Palomar collect from an astronomical source than can the unaided human eye (with a diameter of 5 mm)?
A) 106 or 1,000,000 times
B) 1000 times
C) 10,000 times
D) 5000 times
107. By what factor is the light-gathering power of the 10-m diameter Keck telescope on Mauna Kea in Hawaii greater than an average unaided human eye, with a typical aperture diameter of 5 mm?
A) 2.5 × 105 times
B) 2 × 104 times
C) 2000 times
D) 4 × 106 times
108. A particular reflecting telescope has an objective mirror with a focal length of 1.2 m and an eyepiece lens of focal length 6 mm. What is the magnifying power of this telescope?
A) 200×
B) 20×
C) 2000×
D) 5×
109. A particular reflecting telescope has a primary mirror 0.4 m in diameter and 4.0-m focal length and an eyepiece lens 1.0 cm in diameter and 2.0-cm focal length. What is the magnifying power of this telescope?
A) 20×
B) 200×
C) 40×
D) 400×
110. Which of these characteristics of an astronomical telescope is the MOST important for determining the angular resolution?
A) magnifying power of the telescope
B) focal length of the objective lens or mirror
C) focal length of the eyepiece
D) diameter of the objective lens or mirror
111. In general, doubling the diameter of an optical telescope will
A) quadruple the light-gathering power and improve the angular resolution by a factor of 2.
B) quadruple the light-gathering power and improve the angular resolution by a factor of 4.
C) double the light-gathering power and improve the angular resolution by a factor of 2.
D) double the light-gathering power and improve the angular resolution by a factor of 4.
112. How can one increase the magnification of a refracting telescope without decreasing the light-gathering power?
A) Decrease both the diameter and the focal length of the objective lens.
B) Increase the focal length of the eyepiece.
C) Decrease the focal length of the eyepiece.
D) Increase the diameter of the eyepiece.
113. The angle between two adjacent stars whose images can just barely be distinguished by the telescope is a measure of the telescope’s
A) light-gathering power.
B) resolution.
C) magnification.
D) coudé focus.
114. A Cassegrain telescope has a primary mirror with a 5-m diameter and a hole of diameter 5 cm through the primary mirror. By what percent is the light-gathering power of the mirror reduced because of the hole?
A) 0.01%
B) 1%
C) 20%
D) 50%
115. The secondary mirror of a telescope whose primary mirror is 4 m in diameter has a diameter of 0.5 m. What fraction of the incoming light is obstructed by this secondary mirror?
A) about 1.6%
B) about 1/8, or 12.5%
C) about 35%
D) about 16%
116. A department store sells an “astronomical telescope” with an objective lens of 30-cm focal length and a diameter of 5 cm, and an eyepiece lens of focal length 5 mm and diameter 4 mm. What is the magnifying power of this telescope?
A) 6×
B) 150×
C) 60×
D) 12.5×
117. A refracting telescope has an objective lens of focal length 40 cm and a diameter of 10 cm, and an eyepiece of focal length 5 cm and diameter 1 cm. What is the magnifying power of this telescope?
A) 10×
B) 40×
C) 2×
D) 8×
118. A small refracting “spyglass” telescope has an objective lens with a diameter of 2 inches. The world’s largest refracting telescope at Yerkes Observatory has an objective lens with a diameter of 40 inches. Assuming that all light striking the objective lenses passes through them, how much larger is the light-gathering power of Yerkes than the spyglass?
A) twice
B) 40 times
C) 80 times
D) 400 times
119. A small refracting “spyglass” telescope has an objective lens with a focal length of about 30 inches. The world’s largest refracting telescope at Yerkes Observatory has an objective lens with a focal length of 63.5 feet. If they both use the same eyepiece, how much larger is the image with Yerkes than with the spyglass?
A) about twice
B) about 16 times
C) about 25 times
D) about 625 times
Section: 3-8
120. The BEST shape for the cross-section of a simple astronomical mirror in order to produce the sharpest images of very distant objects at its prime focus is a(n)
A) parabolic shape.
B) elliptical shape.
C) perfectly flat, smooth surface.
D) spherical shape.
121. What is refraction of light?
A) breaking of white light into its composite colors
B) change in direction of a light ray when it reflects on a material more dense than the one in which it is traveling
C) absorption of light as it traverses a dense, transparent material
D) change in direction of a light ray as it passes at an angle from one transparent material to another that has a different optical density
122. Refraction is the
A) bending of light as it enters a dense but transparent material at an angle to the perpendicular to the surface of the material.
B) bending of light around the sharp edge of an obstacle.
C) change in direction of light when it bounces off a smooth surface.
D) change in the color of light when it enters a transparent but colored material, such as glass.
123. Which way does a light ray bend when it crosses the plane smooth surface of a dense transparent material (from air or a vacuum) at an angle to the perpendicular?
A) The light ray does not bend at all because the material is transparent.
B) The light ray bends toward the perpendicular.
C) The light ray bends so that it travels perpendicular to the surface.
D) The light ray bends away from the perpendicular.
124. When light in air or a vacuum enters the plane surface of a dense, transparent medium at an angle to the perpendicular to this surface, which way does the light ray bend?
A) The light ray bends away from the perpendicular.
B) The light ray does not bend at all because the material is transparent.
C) The light ray bends toward the perpendicular.
D) The light ray bends so that, whatever the incoming angle, the light travels along the perpendicular to the surface.
125. When a light ray in air or a vacuum hits the surface of a piece of perfectly smooth, flat glass at an angle and enters the glass, it will
A) reverse its direction and return along its original path.
B) bend toward the perpendicular to the surface.
C) bend away from the perpendicular to the surface.
D) not change its direction at all.
126. When a ray of light enters the flat smooth surface of a dense transparent material at an angle to the perpendicular, which way does it bend?
A) away from the perpendicular
B) toward the perpendicular
C) in a direction so that it travels perpendicular to the surface
D) It does not bend at all because the material is transparent.
127. As a light ray leaves a glass surface, traveling from the glass back into air at an angle to the surface, the light ray
A) bends away from the perpendicular to the surface.
B) bends so that it travels exactly along the perpendicular to the surface.
C) bends toward the perpendicular to the surface.
D) travels in a straight line without bending.
128. Which of these statements correctly describes the refraction of light?
A) A light ray reverses its direction of travel after striking a mirror surface.
B) The path of a ray of light bends as the light enters or leaves a dense, transparent medium such as glass or water.
C) A ray of light is partially absorbed as it enters the denser material.
D) A ray of light spreads out after passing through an opening because of the wave nature of light.
129. How does the speed of light in a substance such as glass compare to the speed of light in a vacuum?
A) The speed of light in glass is faster than the speed of light in a vacuum.
B) The speed of light is the same in both, equal to 299,792.458 km/s.
C) The speed of light in glass is slower than the speed of light in a vacuum.
D) The speed of light in glass can be faster or slower than the speed of light in a vacuum, depending on the type of glass.
130. Compared to the speed of visible light in a vacuum (or in space), the speed of visible light in water or in glass is
A) greater.
B) less.
C) exactly the same because the speed of light cannot vary.
D) much greater.
131. The speed of light always has the same value in a vacuum
A) but its speed inside a transparent material depends on the temperature of the material and can be faster or slower than its speed in a vacuum.
B) as well as in transparent materials.
C) but is slower in transparent materials such as water and glass.
D) but is faster in transparent materials such as water and glass.
132. When light passes from air into a dense but transparent material such as glass, it
A) slows down.
B) maintains its speed, as required by the laws of physics.
C) changes its speed to that of sound in the medium.
D) speeds up.
133. Light enters the smooth flat surface of a block of glass from the vacuum of space (e.g., a spacecraft window). What is the speed of light inside the glass compared to that in a vacuum?
A) The speed will depend on the angle that the light ray makes with the perpendicular to the surface, becoming slower as the angle increases.
B) same because the speed of light is constant, by definition
C) faster because the glass is denser than the vacuum
D) slower because the glass is denser than the vacuum
134. Light enters a plane-parallel block of glass from the vacuum of space and leaves again into space through the opposite side (e.g., in a space-borne instrument). What is the speed of light after it leaves the glass?
A) same speed as it had before it entered the glass
B) The exit speed will depend on the thickness of the glass, becoming slower the thicker the glass.
C) faster than when it entered because it has passed through the dense glass
D) slower because it has passed through the glass and been slowed by it
135. Which characteristic property of a glass lens is the MOST important in bending light rays to form a focused image?
A) color of the glass
B) curvature and shape of its surfaces
C) thickness of the center of the lens
D) diameter or size of the lens
136. What is the main optical element of a refracting telescope?
A) plane (flat) mirror
B) curved mirror
C) Prism
D) Lens
137. A refracting telescope is the type that uses, as its main optical element, a
A) lens.
B) prism of glass.
C) combination of many small plane mirrors.
D) mirror.
138. Which type of telescope uses a lens as the main optical element?
A) radio telescope
B) Newtonian telescope
C) Cassegrain telescope
D) refracting telescope
139. At what distance from the objective lens in a refracting telescope is the primary image formed—that is, at what distance would a person place photographic film if one wanted to take a photograph?
A) its focal length
B) its diameter
C) twice its focal length
D) immediately behind the lens to collect the most light
140. A typical refracting telescope is made up of
A) a long-focal-length lens at the front and a short-focal-length lens at the rear (next to a person’s eye as one looks through the telescope).
B) two mirrors, one concave, the other convex.
C) a mirror that gathers and focuses the light and a lens next to a person’s eye through which one examines the image.
D) a short-focal-length lens at the front and a long-focal-length lens at the rear (next to a person’s eye as one looks through the telescope).
141. How far apart should the objective lens and the eyepiece lens be in a refracting telescope? See Figure 3-18.
A) distance equal to the focal length of the objective lens
B) distance equal to the focal length of the eyepiece lens
C) distance equal to the focal length of the objective lens minus the focal length of the eyepiece lens
D) distance equal to the sum of the focal lengths of the two lenses
142. To what does the term “aberration” in a telescope refer?
A) absorption of light by the glass in the lenses
B) magnifying power of the telescope
C) fundamental limitation of any telescope to resolve very small details in the image
D) defect in design that blurs or distorts the image
143. A lens with spherical surfaces suffers from spherical aberration because
A) the lens sags under its own weight, distorting the image.
B) the starlight is distorted by turbulence in Earth’s atmosphere.
C) different colors are focused at different distances from the lens.
D) different parts of the lens focus the light at different distances from the lens.
144. Spherical aberration occurs in a lens when it is
A) not spherical enough.
B) not exactly the same shape on each side.
C) spherical.
D) parabolic.
145. A ray of light enters a spherical lens. The effective focal length of the lens is determined by each of these EXCEPT
A) the curvature of the lens.
B) the distance from the center line at which the ray enters the lens.
C) the placement of the eyepiece.
D) the wavelength of the light.
146. Which of these types of telescopes is MOST seriously affected by chromatic aberration?
A) radio telescope
B) refracting telescope
C) Newtonian telescope
D) Cassegrain telescope
147. Chromatic aberration is the failure of a telescope objective lens to bring all colors of light to the same focus and appears in
A) only a reflecting telescope.
B) both reflecting and refracting telescopes.
C) all telescopes because it is caused by a basic property of light.
D) only a refracting telescope.
148. When visible light passes through a glass prism or a glass lens, which wavelengths of light are deflected MOST by the glass? See Figure 3-21.
A) the longer wavelengths
B) The light is not deflected by glass because glass is transparent.
C) All wavelengths have their directions changed by the same amount.
D) the shorter wavelengths
149. What causes chromatic aberration in the objective lens of a telescope?
A) Reflection of light back and forth inside the lens produces multiple images and the overall combination of the images will be distorted.
B) Different colors are refracted through different angles at each surface of the lens.
C) Different colors suffer different amounts of absorption by the glass in the lens.
D) The shape of the lens surface distorts the image.
150. What is chromatic aberration in a telescope?
A) Light of different colors reflecting from the objective mirror of the telescope comes to a focus at different points in front of the mirror.
B) Light of different colors comes to a focus at different points behind the objective lens inside the telescope.
C) Light striking the lens at different distances from the center of the lens comes to a focus at different points inside the telescope.
D) The objective lens varies in thickness from center to edge, and light passing through the different thicknesses suffers different amounts of absorption, thereby coloring the image.
151. Chromatic aberration occurs in a refracting telescope when
A) the different colors of light do not focus at the same point.
B) some wavelengths are scattered out of the telescope by imperfections in the glass in the lenses or are reflected back by the front surface of the lens.
C) the lenses bend under their own weight, distorting the final image.
D) light from some wavelengths is absorbed by the lenses, distorting the colors of objects.
152. How is chromatic aberration MOST often corrected in a modern refracting telescope?
A) by using a combination of two lenses made from different types of glass
B) by painting the inside of the telescope jet black to minimize reflections
C) by grinding the lens surfaces into a parabolic shape
D) by using a prism to recombine the colors into white light
153. Chromatic aberration, the inability of a simple lens to focus all colors of light to the same focal point, is reduced in astronomical telescopes by
A) adding a carefully shaped mirror to the lens to produce a lens-mirror combination.
B) combining two lenses of different shape, made from the same kind of glass.
C) bending the lens in its mounting.
D) combining two lenses of different shape, made from different kinds of glass.
154. The largest refracting telescope in the world is the 102-cm (40 in.) telescope at Yerkes Observatory, built in 1897. Why have no larger refracting telescopes ever been built?
A) Larger lenses would have too much chromatic aberration.
B) The sagging of larger lenses under their own weight would produce image distortion.
C) The thickness of larger lenses would produce too much spherical aberration.
D) Larger lenses would produce too much magnification.
155. What is the reason for the fact that a reflecting telescope used at prime focus does not suffer from chromatic aberration?
A) The aluminum coating on the mirror absorbs light from all wavelengths except the one of interest to the astronomer, and this light is focused perfectly.
B) The light has passed through only one lens.
C) All wavelengths of light are reflected by the same amount, regardless of color.
D) The lens is so perfectly formed that all colors of light travel through the lens along the same path.
156. If a person wants to build a telescope having the LEAST possible amount of chromatic aberration, one should use
A) a front lens that has been coated with a special material to reduce refraction.
B) a front lens that is composed of two closely spaced lenses made of different kinds of glass.
C) the thinnest front lens that one can obtain.
D) mirrors instead of lenses.
157. A spherical mirror suffers from spherical aberration because
A) different colors are focused at different distances from the mirror.
B) a mirror of this shape is structurally weak and will sag under its own weight, distorting the image.
C) the starlight is distorted by turbulence in Earth’s atmosphere.
D) different parts of the mirror focus the light at different distances from the mirror.
158. Which of these statements describing a disadvantage of large refracting telescopes when compared to large reflecting telescopes is NOT correct?
A) Sagging of the primary optical element under its own weight is a problem with refracting telescopes but not with reflecting telescopes.
B) Refracting telescopes suffer from chromatic aberration, whereas reflecting telescopes do not.
C) Refracting telescopes can suffer from spherical aberration, whereas reflecting telescopes cannot.
D) Air bubbles in the glass are more of a problem in refracting telescopes than in reflecting telescopes.
Section: 3-9
159. Spherical aberration can be corrected or avoided in a reflecting telescope by
A) grinding the mirror to a more accurate spherical curve.
B) grinding the mirror to a parabolic shape.
C) using light of only one color.
D) grinding the mirror to an elliptical shape.
160. The reason that the primary mirror of an astronomical telescope is often shaped and polished to a parabolic shape is
A) to avoid the chromatic aberration that would be produced by an equivalent spherical mirror.
B) that it is lighter and easier to mount in a telescope because it requires less glass than an equivalent spherical mirror.
C) that it is easier to produce, even though the resulting mirror will produce more spherical aberration than an equivalent spherical mirror.
D) to avoid spherical aberration by bringing parallel rays to a single focus.
161. How is spherical aberration eliminated in a reflecting telescope?
A) by using the Cassegrain focus of the telescope
B) by making the primary mirror very thin
C) by grinding the primary mirror surface to a parabolic shape
D) by bending the photographic film into a concave shape
162. What are the basic parts of a Schmidt-Cassegrain telescope?
A) spherical, concave primary mirror, and glass corrector plate
B) parabolic, concave primary mirror, and convex secondary mirror
C) parabolic, concave primary mirror, and concave secondary mirror
D) parabolic, concave primary mirror, and flat, diagonal secondary mirror
163. Schmidt-Cassegrain telescopes
A) have parabolic mirrors created by spinning liquid glass.
B) give only narrow-angle images.
C) are compact.
D) allow great magnification.
164. A discovery useful to telescope makers was made by Isaac Newton, namely that the surface of a liquid spun in a circle assumes the shape of a
A) sphere.
B) parabola.
C) ellipse.
D) hyperbola.
165. Which combination of optics is used in the Schmidt-Cassegrain telescope for producing high-quality wide-angle images of the sky?
A) single, short-focal-length spherical mirror
B) parabolic mirror of short focal length, used at prime focus
C) two lenses of different glass, one convex, the other concave, to reduce chromatic aberration
D) spherical primary mirror with a thin correcting lens ahead of it
166. Which of these telescopes consists of a concave, spherical primary mirror and a glass corrector plate to correct for the spherical aberration in the primary?
A) Newtonian telescope
B) refracting telescope
C) Cassegrain telescope
D) Schmidt telescope
167. What is the purpose of the glass corrector plate at the front of a Schmidt telescope?
A) The plate reflects unwanted wavelengths away from the primary mirror.
B) The plate corrects for spherical aberration in the primary mirror.
C) The plate corrects for chromatic aberration in the primary mirror.
D) The plate corrects for sagging of the primary mirror under its own weight when the telescope is turned at an angle to the vertical.
168. Schmidt telescopes are used mostly for
A) tracking artificial satellites in Earth orbit.
B) photographing wide areas of the night sky.
C) high-magnification views of faint, distant galaxies and quasars.
D) photography of planets, using high magnification.
169. The main use of the Schmidt-type telescope, which uses a spherical primary mirror and a refracting “corrector plate,” is for
A) narrow field-of-view photography and photometry.
B) single-star spectroscopy.
C) wide-angle photography for sky surveys.
D) radio astronomy.
Section: 3-10
170. Increasing the exposure time of an image made through a telescope will
A) brighten the image.
B) increase the magnification.
C) increase the resolution.
D) leave the image unchanged.
171. If a person increases the exposure time of an image taken with a certain telescope, one will also increase the
A) brightness.
B) magnification.
C) resolution.
D) sharpness.
172. In addition to its capability of being stored, an ordinary (nondigital) photograph has what major advantage over the unaided human eye for astronomical observations?
A) The photograph is sensitive to 70% of the photons that land on it.
B) The photograph can easily be enhanced by feeding its pixels electronically into a computer.
C) The photograph responds to a long exposure time by producing higher resolution.
D) The photograph can be used in conjunction with a filter to observe only certain colors.
173. What percentage of the light falling on a piece of photographic film is typically wasted (does not contribute to the formation of the image)?
A) 2%
B) 18%
C) 45%
D) 98%
174. What is a CCD (charge-coupled device)?
A) detector in which a small electric current is controlled by a bimetallic strip that expands and contracts in response to infrared radiation
B) electronic filter to single out one wavelength or set of wavelengths for studying astronomical objects
C) device in which an image from a photographic plate or film is transferred to a computer by moving static electric charges directly into the computer memory in a manner similar to modern copying machines
D) array of small light-sensitive elements that can be used in place of photographic film to obtain and store a picture
175. What percentage of the light falling on the BEST CCD’s is typically wasted (does not contribute to the formation of the image)?
A) 1%
B) 10%
C) 90%
D) 98%
176. The charge-coupled device (CCD), now used extensively for astronomical imaging, works on what principle?
A) Light from the image modifies the plastic material on a disk, which can then be read on a standard video compact disk (CD) player.
B) A single optical detector generates an electrical signal as it is scanned quickly across the astronomical image.
C) Light generates electrical charge on a computer-readable multi-element array of detectors.
D) Light from the image is detected by new, high-sensitivity, fine-grain, automatically processed film.
177. The detector that in many instances has replaced the photographic plate for astronomical photography is the
A) CCD (charge-coupled device).
B) photomultiplier or image intensifier tube.
C) diffraction grating.
D) interferometer.
178. How much more efficient in collecting incoming photons is the modern charge-coupled device (CCD) compared to a typical photographic plate?
A) about 10 times
B) more than 100 times
C) a little better than a factor of 2
D) about 35 times
179. Charge-coupled devices (CCDs) are used in all of these EXCEPT
A) telescopes.
B) picture-taking cell phones.
C) digital cameras.
D) long-exposure film photography.
Section: 3-11
180. The major cause of blurred and unsharp images of objects observed through very large telescopes at the extreme limit of magnification is the
A) poor tracking capabilities of modern telescopes.
B) poor optical polish achievable on large mirrors.
C) clumsiness of the telescope operator.
D) air turbulence in Earth’s atmosphere.
181. What does the word “seeing” mean to an astronomer using a telescope?
A) twinkling and blurring of the image due to turbulence in Earth’s atmosphere
B) combined effects of aberrations in the components of the telescope, particularly spherical and chromatic aberration
C) effect of wind on the telescope that causes it to vibrate, thereby blurring the image
D) haze or thin cloud in the atmosphere that reduces the brightness and sharpness of the telescope image
182. If one observatory site is described as having better “seeing” than another observatory site, what is it that is better at the first site?
A) The sky is more transparent and there is less haze in the atmosphere at that site, providing brighter and sharper images.
B) The winds are lighter at the better site, thereby producing less telescope vibration.
C) There is less air turbulence at that site, causing less twinkling and blurring of the images.
D) There are more clear nights at that site.
183. Which statement about the twinkling of stars and planets is NOT correct?
A) Stars twinkle less when they are farther from the horizon.
B) A photographic image of more than a few seconds exposure time will show a twinkling star as a disk.
C) Planets twinkle less than stars.
D) Twinkling of stars is an inherent phenomenon and cannot be reduced by any observing technique.
184. It is difficult to improve the angular resolution of optical telescopes located on the surface of Earth beyond a certain limit because
A) large telescopes are reflecting telescopes, and they suffer from too much chromatic aberration.
B) spherical mirrors suffer from too much aberration.
C) star images are distorted more by air turbulence than by the telescope optics.
D) improvement would require much larger, very expensive telescopes to enhance the inherent telescope.
185. The sharpest images of stars that can be formed by a single, large, ground-based, visible-light telescope are of the order of what angular size?
A) about 10–3 arcsecond
B) about 1°
C) about 1 arcminute
D) about 0.2 arcsecond
186. The BEST Earth-based sites for modern large astronomical telescopes, which provide the least seeing effects on astronomical images, are
A) near large cities, where the warm air from human activity serves to stabilize the overlying atmosphere.
B) at sea level, where the air is less turbulent.
C) on the downwind side of mountain ranges, where smooth airflow produces clear air and stable images.
D) on the tops of high mountains, above a large fraction of the disturbing atmosphere.
187. What factor has seriously reduced the effectiveness over the last few years of the 5-m Hale telescope on Mount Palomar, California, formerly the largest telescope in the world?
A) light pollution from nearby cities
B) cracking of the mirror by the Los Angeles earthquake
C) distortion of the mirror surface from repeated exposure to the cold night air on the mountain
D) tarnishing of the mirror surface by air pollution
188. Images from the 5-meter telescope at Mount Palomar are not as clear as they were when the telescope was first put into operation over 60 years ago. Why is this?
A) The quality of the mirror has degraded significantly over time.
B) Precession has changed the positions of a number of important targets so that they are no longer accessible from Palomar.
C) The telescope was recently damaged by an earthquake.
D) Light pollution has increased significantly in the past 60 years.
189. One way to distinguish a star from a planet, particularly when they appear near the horizon, is that stars appear to twinkle and planets shine steadily. Which of these statements is a reasonable explanation for this phenomenon?
A) Stars actually do twinkle—shine with a light that flickers bright and dim—whereas planets shine with a steady, unwavering light.
B) The light from planets is so much brighter than the light from stars (when they are observed from Earth) that it is unaffected by air movement in Earth’s atmosphere.
C) The disk of a planet, as observed from Earth, appears larger than the disk of a star. Thus, if refraction through moving air in Earth’s atmosphere makes the planet’s disk appear to move about slightly, there will normally be a central part of the disk that shines steadily and does not appear to twinkle.
D) Because light from planets is reflected, it is unaffected by the refraction in Earth’s atmosphere.
Section: 3-12
190. The Hubble Space Telescope, placed in orbit by the space shuttle Discovery in 1990, has a primary mirror of diameter
A) 57 m.
B) 1 m.
C) 6 m.
D) 2.4 m.
191. What is the angular resolution of the Hubble Space Telescope?
A) 0.01 arcsecond
B) 0.001 arcsecond
C) 1 arcsecond
D) 0.1 arcsecond
192. The Hubble Space Telescope is NOT designed to investigate
A) visible light.
B) ultraviolet radiation.
C) infrared radiation.
D) radio radiation.
193. After the Hubble Space Telescope was launched, it was found to suffer seriously from
A) scattering of light from dust on the primary mirror surface.
B) too much angular resolution.
C) spherical aberration.
D) chromatic aberration.
Section: 3-13
194. What characteristic of the 10-m Keck telescopes makes them fundamentally different from older telescopes, such as the one on Mount Palomar?
A) They are located in Earth’s orbit, away from all the distortions of Earth’s atmosphere.
B) They are actually four closely spaced telescopes that can be operated together as if they were a single telescope.
C) The primary mirrors are large, very thin pieces of glass that can be deformed rapidly to compensate for seeing.
D) The primary mirror is made up of 36 separate mirror segments.
195. The primary mirrors in the 10-m Keck telescopes consist of
A) a large hollow honeycomb of glass—lightweight but relatively thick to prevent sagging.
B) a large, thin slab of glass whose surface is continuously adjusted by computer-controlled motors.
C) six individual mirrors, mounted so that they all bring the light to the same focus.
D) 36 individual mirrors, mounted so that they all bring the light to the same focus.
196. Which of these techniques is the key factor in a telescope that uses adaptive optics to correct for atmospheric distortion of images, or “seeing”?
A) Computer-controlled motors rapidly adjust the orientation and position of the separate primary mirrors in a multiple-mirror telescope (MMT).
B) A corrector lens compensates for image distortion by electronic control of its shape.
C) Computer-controlled motors adjust the position and shape of one of the small mirrors within the optics many times per second.
D) The light rays are focused electronically, without the use of lenses or mirrors.
197. Why was adaptive optics developed?
A) to prevent the distortion of mirrors by the vacuum of space
B) to compensate for image distortion caused by Earth’s atmosphere
C) to compensate for spherical aberration
D) to prevent distortion by sagging in very thin, lightweight mirrors
198. Adaptive optics involves
A) reconfiguration of the primary mirror to compensate for changes in telescope orientation and temperature.
B) reconfiguration of the primary mirror to compensate for atmospheric distortion.
C) reconfiguration of a secondary mirror to compensate for atmospheric distortion.
D) rapid switching among available eyepiece powers for optimal viewing of the target.
199. One technique that astronomers are now using to increase the amount of detail that can be recorded with telescopes is
A) spinning huge tubs of mercury, thus producing very large parabolic surfaces at relatively low cost.
B) antireflective coatings, where the mirror is coated with a substance such as calcium fluorite to reduce the amount of reflected light.
C) increased size, with mirrors up to 10 m in diameter (far larger than at earlier times), thereby producing greater intrinsic angular resolution.
D) adaptive optics, where the tilt and shape of mirrors in the telescope are changed many times per second to compensate for atmospheric turbulence.
200. Which of these techniques has resulted in the BEST angular resolution of the image?
A) adaptive optics as used with Keck II on Mauna Kea
B) Hubble Space Telescope, an orbiting telescope
C) active optics, as used with the New Technology Telescope in Chile
D) interferometry, as used with the four telescopes of the Very Large Telescope (VLT) at the Paranel Observatory in Chile
Section: 3-14
201. Who first discovered that radio radiation could be received from astronomical objects?
A) Isaac Newton
B) Edwin Hubble
C) Thomas Young
D) Karl Jansky
202. The first person to detect and identify radio emissions coming from deep space was
A) Thomas Edison.
B) Galileo.
C) Arno Penzias.
D) Karl Jansky.
203. What was the first extraterrestrial radio source to be detected?
A) Cassiopeia A (a supernova remnant)
B) the center of our Galaxy
C) Jupiter
D) Sun
204. The first astronomical radio source, identified by Karl Jansky during measurements of sources of radio noise, was
A) the center of our Galaxy.
B) the Crab Nebula.
C) Jupiter.
D) the Orion Nebula.
205. The first radio energy to be detected from outer space came from the
A) center of the Milky Way Galaxy, in the direction of Sagittarius.
B) Sun.
C) Moon.
D) quasar 3C 273.
206. Why did Karl Jansky believe the source of radio static he was detecting in 1932 was not from terrestrial sources?
A) In 1932 there were no strong sources of radio waves on Earth.
B) He could detect the signals coming through Earth as well as from the sky.
C) The radio static was most intense when the Sun was high in the sky.
D) The radio static was most intense when the center of our Galaxy was high in the sky.
207. One major difference between radio waves and light is that
A) light waves are electromagnetic, whereas radio waves are not.
B) radio waves are electromagnetic, whereas light waves are not.
C) radio waves have shorter wavelength than light waves.
D) radio waves have longer wavelength than light waves.
208. Which of these was the first nonvisible radiation to be detected from outer space?
A) X-rays
B) gamma rays
C) radio waves
D) ultraviolet (UV) light
209. The first astronomical radio source was detected and identified in the year
A) 1897.
B) 1945.
C) 1967.
D) 1932.
210. Which of these combinations of components of a telescope will produce the worst angular resolution?
A) smaller diameter lens or mirror or radio dish and longer wavelength electromagnetic radiation
B) larger diameter lens or mirror or radio dish and shorter wavelength electromagnetic radiation
C) larger diameter lens or mirror or radio dish and longer wavelength electromagnetic radiation
D) smaller diameter lens or mirror and shorter wavelength electromagnetic radiation
211. In single-telescope astronomical systems, either optical or radio, the
A) longer the wavelength, the sharper the image.
B) smaller the main mirror or lens or radio dish aperture in general, the sharper the image.
C) larger the main mirror or lens or radio dish aperture in general, the sharper the image.
D) longer the focal length of the primary mirror or lens or radio dish, the sharper the image.
212. How does angular resolution for a given diameter of a telescope depend on wavelength?
A) Angular resolution worsens as wavelength increases.
B) Angular resolution may improve or worsen as wavelength increases, depending on other factors such as intensity and spectral range (e.g., optical, infrared, radio).
C) Angular resolution improves as wavelength increases.
D) Angular resolution depends only on the diameter of the telescope and is independent of wavelength.
213. In telescopes designed for any wavelength of electromagnetic radiation, the angular resolution is worse for
A) larger diameter lenses or mirrors or radio dishes and longer wavelength radiation.
B) larger diameter lenses or mirrors or radio dishes and shorter wavelength radiation.
C) smaller diameter lenses or mirrors or radio dishes and shorter wavelength radiation.
D) smaller diameter lenses or mirrors or radio dishes and longer wavelength radiation.
214. The main reason that the angular resolution of a 20-m diameter radio telescope is worse than that of a 0.5-m diameter optical telescope is that
A) angular resolution becomes worse as wavelength decreases.
B) angular resolution becomes worse as wavelength increases.
C) an optical mirror suffers from chromatic aberration.
D) angular resolution becomes worse as mirror size increases.
215. How does the angular resolution of the 305-m Arecibo telescope in Puerto Rico, which observes radio waves, compare with the angular resolution of the 10-m Keck telescope on Mauna Kea, Hawaii, which observes optical light? Assume each telescope observes the light they were designed to see.
A) It is not possible to compare their angular resolution because they work in different wavelength ranges.
B) The 305-m Arecibo telescope has much better angular resolution than the 10-m Keck telescope.
C) They have about the same angular resolution because angular resolution is limited by turbulence in Earth’s atmosphere, not by mirror diameter.
D) The 305-m Arecibo telescope has much worse angular resolution than the 10-m Keck telescope.
216. How does the resolution of a typical radio telescope compare with the resolution of a typical optical telescope?
A) Resolution becomes worse for longer wavelengths, so radio telescopes generally have poorer resolution.
B) Resolution becomes better for longer wavelengths, so radio telescopes generally have better resolution.
C) Resolution depends on both wavelength and telescope size. Because radio telescopes are so large, the resolution is about the same as for an optical system.
D) Resolution depends entirely on the separation of the objects being imaged, so radio and optical telescopes have the same resolution.
217. How is interferometry used in radio astronomy?
A) Signals from a radio source are combined with an equivalent signal delayed in time to produce interference, thereby increasing the angular resolution of the telescope.
B) Signals from different places around the dish of a radio telescope are combined to produce interference and increase the angular resolution of the telescope.
C) Signals from two or more different radio telescopes are combined to produce a single image of greater angular resolution than from any one telescope alone.
D) Signals from different parts of a radio source are combined to increase the angular resolution of the telescope.
218. How does the angular resolution (sharpness) of the images obtained from radio telescopes using very long baseline interferometry (VLBI) compare to the typical angular resolution of optical telescopes?
A) VLBI images are about 10 times less sharp than the best optical images.
B) VLBI images are much sharper.
C) VLBI images are very much less sharp because of the longer wavelength.
D) VLBI images have about the same resolution as the best optical images, about 0.2 arcseconds.
219. The primary reason for spreading many radio telescopes across a large area and combining the signals at a central station is to
A) produce much sharper images of radio sources.
B) ensure that cloudy weather affects only a few of the telescopes, leaving the others to continue observing.
C) avoid interference between signals from the separate telescopes.
D) collect more radiation than would be possible with the same telescopes clustered together.
220. What is the main reason for using several radio telescopes together as an interferometer?
A) to obtain much better angular resolution or sharpness in the images
B) to ensure that at least one of the telescopes is in a radio-interference-free zone
C) to collect more radiation from very faint sources
D) to ensure that observations are uninterrupted by the failure of one or two telescopes
221. What is the maximum angular resolution (sharpness of the image) obtainable with radio telescopes on Earth?
A) 0.00001 arcsecond using the worldwide very long-baseline interferometry (VLBI) array of telescopes
B) 100 arcseconds using the 305-m Arecibo telescope in Puerto Rico
C) 0.0001 arcsecond using the very long-baseline array of telescopes extending across the United States and including Hawaii
D) 0.1 arcsecond using the 27-dish very large-array (VLA) of radio telescopes at Socorro, New Mexico
222. A radio telescope
A) is very similar to a refracting optical telescope.
B) is very similar to a reflecting optical telescope.
C) is completely different in design from any optical telescope.
D) combines major features of both refracting and reflecting optical telescopes.
Section: 3-15
223. Which substance in Earth’s atmosphere is the main absorber of infrared radiation from space?
A) methane
B) water vapor
C) ozone
D) carbon dioxide
224. The main absorber in the atmosphere for infrared radiation, which impedes observations of astronomical infrared objects, is
A) water vapor, H2O.
B) nitrogen and oxygen (N2 and O2), the major constituents of the atmosphere.
C) electrons and ionized atoms in Earth’s ionosphere.
D) dust.
225. The main reason for placing a telescope and scientific equipment into an aircraft to carry out infrared astronomy is to
A) obtain photographs of resolution higher than can be obtained on the ground.
B) avoid stray IR radiation from the warm Earth and its occupants.
C) avoid the absorption of the IR radiation by water vapor.
D) obtain longer observing times on specific sources by moving in the direction of Earth’s rotation.
226. A high mountaintop such as Mauna Kea in Hawaii is a good site for an infrared observatory primarily because it is
A) above the absorbing ozone layer.
B) farther from city lights.
C) above a significant proportion of the moisture in Earth’s atmosphere.
D) above most of the turbulence in Earth’s atmosphere.
227. Telescopes designed to observe infrared radiation
A) must be placed in orbit above Earth’s atmosphere.
B) can be placed on Earth’s surface as long as the altitude is high enough to avoid water vapor, the prime absorber of infrared radiation in the atmosphere.
C) can be placed on Earth’s surface as long as the altitude is high enough to avoid carbon dioxide, the prime absorber of infrared radiation in the atmosphere.
D) can be placed at any convenient location on Earth’s surface because infrared radiation penetrates one of the “windows” of transparency in the atmosphere.
228. It is difficult to do infrared astronomy at sea level primarily because of what component in Earth’s atmosphere?
A) water vapor
B) carbon dioxide
C) ozone
D) chlorofluorocarbons (CFCs)
229. Telescopes are placed in space to view distant galaxies primarily to
A) get closer to the observed objects.
B) avoid the absorption and distortion of the light or other radiations within the atmosphere of Earth.
C) avoid having to steer the telescope against Earth’s motion.
D) avoid the light pollution from Earth’s populated areas.
230. Astronomy from space vehicles is particularly useful because the telescope
A) is in a gravity-free state; the mirror is not distorted by gravitational stress and can therefore produce sharper images.
B) moves smoothly and without vibration in a constant orbit and can therefore produce sharp photographs.
C) is above Earth’s absorbing and distorting atmosphere and can measure radiation over a very wide wavelength range.
D) is in a clean, dust-free environment and scattered light is much reduced.
231. What is the main reason for placing astronomical telescopes and detectors on satellites?
A) to avoid light pollution from cities and other built-up areas
B) to avoid dust and haze in Earth’s atmosphere
C) to get above the absorption in Earth’s atmosphere
D) to get closer to the objects being viewed
232. Which was the first satellite to be dedicated to infrared astronomy?
A) Hubble Space Telescope (HST)
B) International Ultraviolet Explorer (IUE)
C) Extreme Ultraviolet Explorer (EUVE)
D) Infrared Astronomical Satellite (IRAS)
233. The IRAS satellite, placed in orbit in 1983 to survey the whole sky, detected which kind of electromagnetic radiation?
A) infrared
B) X-ray
C) ultraviolet
D) visible light
234. Which was the first satellite to be dedicated to ultraviolet astronomy?
A) Hubble Space Telescope (HST)
B) Infrared Astronomical Satellite (IRAS)
C) Extreme Ultraviolet Explorer (EUVE)
D) International Ultraviolet Explorer (IUE)
Section: 3-16
235. Devices to detect X-rays once they have been focused include all of these EXCEPT
A) CCDs.
B) scintillators.
C) calorimeters.
D) Schmidt corrector plates.
236. In which wavelength range does the astronomical satellite known as the Compton Observatory observe?
A) ultraviolet
B) X-ray
C) gamma ray
D) infrared
237. What technique is necessary to produce a telescope for focusing X-rays from astronomical sources?
A) The telescope must be placed at high-altitude mountain sites because the X-rays penetrate only this far into the atmosphere.
B) The main mirror must be cooled to prevent the highly energetic X-ray photons from heating and distorting it, thereby producing poor images.
C) The X-rays must be reflected at grazing incidence to the mirror surface; otherwise they will simply pass straight through the mirror.
D) The mirror surface has to have a thick aluminum coating in order to reflect the highly penetrating X-rays.
238. Normal reflecting telescopes, with minor adjustments, can be made capable of detecting all of these EXCEPT
A) infrared radiation.
B) visible radiation.
C) near ultraviolet radiation.
D) X-ray radiation.
239. Do people use astronomical gamma ray detectors on Earth’s surface?
A) No. The atmosphere blocks all gamma rays from space. Thus, people cannot use gamma ray detectors on Earth’s surface.
B) Yes. Gamma rays have a narrow “window” through Earth’s atmosphere. So, people can detect enough of them to form images.
C) Yes, but these detectors are actually pointed downward to detect rays coming through Earth. Only cosmic gamma rays have enough energy to penetrate Earth, which acts as a filter for gamma rays generated by terrestrial sources.
D) Yes, but these detectors actually detect Cherenkov radiation produced by particles struck by gamma rays high in the atmosphere. Thus, the gamma ray detection is very indirect.
240. Gamma rays are generally absorbed in Earth’s atmosphere. However, it is possible to build Earth-based observatories that detect secondary effects of gamma rays, such as the blue light produced when the particles they collide with move faster than the speed of light in air. This blue light is called
A) synchrotron light.
B) Cherenkov light.
C) ultraviolet light.
D) superluminal light.
Section: 3-17
241. Cosmic rays are
A) electromagnetic waves that originate from space.
B) X-rays originating from the Sun.
C) neutrinos.
D) high-energy particles traveling at nearly the speed of light.
242. MOST moderate energy cosmic rays originate from
A) the Sun.
B) supernova debris colliding with gas in the interstellar medium.
C) charge-coupled devices.
D) the Big Bang.
243. The highest-energy cosmic rays detected on Earth have energies comparable to
A) the most energetic radio photons.
B) a car traveling at 60 miles per hour.
C) a baseball thrown by a major league pitcher.
D) a supernova.
244. Which of these items poses the greatest hazard to energy grids on Earth?
A) low-energy cosmic rays emitted by the Sun
B) X-rays originating from the Sun
C) gamma rays from active galactic nuclei
D) ultrahigh-energy cosmic rays
245. Astrophysicists MOST often detect high-energy cosmic rays by
A) positioning particle detectors in space.
B) observing showers of lower energy particles and photons generated when the primary cosmic ray interacts with matter in Earth’s atmosphere.
C) observing their interactions with large tanks of material deep underground.
D) reflecting them at grazing incidence off custom-designed mirrors.
246. Large arrays of detectors are useful in studying cosmic rays because
A) cosmic ray showers move in slightly different directions than the primary cosmic rays from which they originate.
B) cosmic rays are so rare.
C) they help discriminate cosmic rays from unrelated background events.
D) cosmic rays travel near the speed of light.
247. What is Cherenkov radiation?
A) radiation that moves faster than the speed of light
B) radiation emitted directly from the core of the Sun to Earth
C) radiation emitted when a charged particle moves through a material medium faster than the speed of light through that medium
D) radiation emitted during the transformation of one kind of neutrino (electron, muon, or tau neutrino) to another kind of neutrino
Section: 3-18
248. What is a neutrino?
A) particle with the same mass as an electron but with no electrical charge
B) uncharged proton
C) positively charged electron that combines with an ordinary electron to form an uncharged “light atom”
D) chargeless particle with a very small mass, a small fraction of that of the electron
249. The neutrino is
A) a heavy, uncharged nuclear particle, easily detected.
B) another name for an electron that carries a positive charge instead of a negative charge.
C) a very small asteroidlike body orbiting the Sun.
D) an elusive, subatomic particle having little mass which is difficult to detect.
250. The neutrino is
A) a tiny particle that interacts very weakly with matter, with extremely low mass and no charge.
B) another name for the neutron, a component of almost all atomic nuclei, with a mass close to that of the proton and having no charge.
C) another name for a photon of very high-energy (i.e., short-wavelength) electromagnetic radiation with great penetrating power.
D) a massive but very elusive nuclear particle that carries most of the energy generated in the core of the Sun to the surface, but then decays to release electromagnetic radiation (i.e., light).
251. What happens to MOST of the neutrinos produced by the nuclear reactions in the core of the Sun?
A) Most neutrinos combine with protons to form neutrons.
B) Most neutrinos collide and stick together with protons to form helium nuclei.
C) Most neutrinos collide with electrons, producing energy.
D) Most neutrinos escape from the Sun into space.
252. A neutrino produced in the nuclear furnace in the core of the Sun can penetrate easily through the
A) gas of the Sun’s interior and through the solid Earth.
B) Sun’s gaseous interior, but it will be stopped at the surface of the solid Earth.
C) Sun’s interior, but it will be deflected away from Earth by its magnetic field.
D) gaseous interior of the Sun and the solid Earth, but it will be easily stopped by chemicals containing chlorine.
253. Which technique was the first to be used to detect solar neutrinos?
A) proton-proton reaction in which neutrinos play an intermediate role
B) interaction of neutrinos with water molecules in huge underground tanks
C) production of radioactive argon nuclei by neutrino interaction with chlorine nuclei in deep underground tanks
D) interactions of neutrinos with radioactive argon nuclei to produce chlorine nuclei, which are then measured chemically
254. The solar neutrino experiment designed by Raymond Davis more than 40 years ago consistently measured a rate of solar neutrinos arriving at Earth that is
A) almost exactly equal to the predicted rate.
B) less than 1% of the predicted rate.
C) almost double the predicted rate.
D) about 1/3 of the predicted rate.
255. Before 1998, what results were obtained in the detection of solar neutrinos?
A) No neutrinos were detected at all.
B) About 6 times as many neutrinos were observed as were expected from theoretical models of the Sun.
C) The neutrinos were about twice as energetic on average as was predicted by theoretical models of the Sun.
D) Only about 1/3 of the expected number of neutrinos were observed, compared with theoretical models of the Sun.
256. Recent solar neutrino experiments have confirmed the suspicion that the explanation for the apparent shortfall in neutrino detection rates over the past 30 years is that
A) the Sun does indeed produce only 1/3 of that predicted by earlier theoretical models; these models require major modification.
B) 2/3 of the neutrinos from the Sun are absorbed by material between the Sun and Earth.
C) 2/3 of the solar neutrinos transform into types of neutrinos that were undetectable by old detection techniques.
D) the detectors were faulty; 2/3 of the neutrinos were missed by the detectors.
257. In measuring solar neutrinos, what would one expect for the variation in the rate of detection in any instrument?
A) The detection rate would rise at sunset and sunrise because solar neutrinos are gravitationally deflected by Earth to increase this rate at these times.
B) The rate would remain constant, day and night, because neutrinos pass very easily through Earth.
C) The instrument would only detect neutrinos in the daytime because Earth would block these particles during the night.
D) The instrument would measure more neutrinos during the night than in daytime because solar neutrinos would react with nuclei in Earth to produce more neutrinos at that time.
258. Which of these statements seems to be the correct explanation for the low neutrino rates detected by Davis and others?
A) The neutrinos change their nature en route from the Sun to Earth.
B) The core of the Sun is actually about 10% cooler than had been originally predicted.
C) The Davis result was subject to much uncertainty because it measured only a small-yield side branch of the main nuclear reaction.
D) The neutrinos Davis detected were coming not from the Sun but instead from sources within Earth.
259. In a modern neutrino detector, neutrinos
A) are detected directly by photomultipliers that emit an electrical signal when struck by a neutrino.
B) strike water molecules, converting them into molecules of heavy water that then sink to the bottom of the tank.
C) cause reactions that emit Cherenkov radiation that is then detected with photomultipliers.
D) that have electric charge are focused by a series of magnets to produce an intense beam that can be detected more easily by conventional detectors.
260. What is the important difference between modern neutrino detectors and the chlorine-argon detection system of previous decades?
A) The new detectors are smaller and thus can be built more cheaply.
B) The new detectors can be tuned to detect neutrinos of any energy.
C) The new detectors are able to detect all three neutrino types, not just those originally emitted from the Sun.
D) The new detectors are in orbit above our atmosphere, thus avoiding the loss of neutrinos absorbed in Earth’s atmosphere.
261. One technique for the detection of neutrinos from outer space involves the reaction of neutrinos with deuterium in a water tank, with the resulting high-speed electron then generating Cherenkov radiation in the water. How is the Cherenkov radiation produced?
A) by the passage of the charged electron through the water at a speed greater than the speed of light in a vacuum
B) by the recombination of the electron with a proton to produce neutral hydrogen and Balmer series line emissions
C) by the annihilation of a positron in the water by the electron
D) by the charged electron moving in the water faster than the speed of light in water
262. In a Cherenkov radiation detector a neutrino
A) passing through water is slowed down and emits a flash of light.
B) interacts with a deuterium nucleus, forcing the emission of an electron that moves faster than light in water and emits a flash of light.
C) interacts with a hydrogen atom forcing it to move rapidly through water and emit a flash of light.
D) strikes a photomultiplier, causing it to emit a flash of light.
263. Which one of these properties does the neutrino NOT possess?
A) The neutrino travels at nearly the speed of light.
B) The neutrino is highly penetrating through any matter.
C) The neutrino has extremely small mass.
D) The neutrino has an electrical charge equal to that on the electron.
264. It is now understood that there are three “flavors” of neutrinos. These do NOT include the
A) electron neutrino.
B) proton neutrino.
C) tau neutrino.
D) muon neutrino.
265. How was the “solar neutrino problem,” that is, the detection of only a third of the predicted number of solar neutrinos, finally resolved?
A) It was found that the detection system was faulty and missed many neutrinos it should have counted.
B) The energy of the neutrinos to be detected had been miscalculated, and different detectors were required to detect neutrinos in the correct range.
C) The basic physics of the emission of neutrinos in nuclear reactions had been misunderstood, and the predicted number was incorrect.
D) On the way from the Sun to Earth the neutrino beam changes to a mixture of three types of neutrinos, only one of which was being detected.
Section: 3-19
266. Gravitational radiation causes
A) the rest masses of objects to oscillate.
B) periodic ripples in the distances between objects.
C) gamma rays.
D) pulsar magnetic fields.
267. Figure 3-43 shows two examples of
A) quadrupole oscillations.
B) the oscillations causing Cepheid variable stars.
C) features in the cosmic microwave background.
D) cosmic ray showers.
268. An object oscillates in one of the patterns shown by Figure 3-43. It might be a particularly interesting astronomical source because these patterns are well-suited to produce
A) supernovae.
B) Balmer line emission.
C) ultrahigh-energy cosmic rays.
D) gravitational waves.
269. Two neutron stars orbit each other. Careful observations show that they are spiraling toward each other and thus losing energy from their orbit. How might people detect this energy?
A) neutrinos
B) gamma ray bursts
C) gravitational waves
D) Hawking radiation
270. Gravitational radiation has been found
A) indirectly, by measuring changes in the orbits of neutron stars.
B) directly, by using lasers to measure tiny changes in distances on Earth.
C) In both A and B.
D) by neither A nor B; gravitational radiation is only a theoretical idea.
271. The first evidence for gravitational waves came from
A) mapping the orbits of stars near the center of our Galaxy.
B) periodic ripples in the distances between objects.
C) the cosmic microwave background.
D) the changing orbits of neutron stars.
272. How much would a distance of 1 meter appear to change because of the typical ripples in spacetime generated by stellar remnants?
A) by 10–20 m
B) by 10–10 m
C) by 10-–5 m
D) by 10–1 m
273. How have astrophysicists detected gravitational waves?
A) Large underground water tanks show flashes of light when gravitational waves interact with their constituent particles.
B) Lasers measure tiny changes in distances as gravitational waves pass.
C) They detect showers of particles when the gravitational waves interact with Earth’s atmosphere.
D) Gravitational waves have not yet been detected
274. Why do astronomers require measurements from at least three gravitational wave detectors to identify the source of a gravitational radiation signal?
A) Gravitational waves have a wavelength of about a thousand kilometers, requiring detections across large distances.
B) Gravitational waves are so weak that several detectors are required to confirm a signal.
C) Three detections are required to separate real gravitational waves from locally generated noise.
D) The time delay between the different detectors allows astronomers to identify the direction of the source.
275. What is the source of MOST of the gravitational waves detected directly over the past several years?
A) the merger of two black holes
B) the merger of two neutron stars
C) the disruption of a star by a supermassive black hole
D) the merger of two supermassive black holes