Full Test Bank Atomic Physics and Spectra Chapter 4 - Discovering the Universe 14e Test Bank + Answers by Neil F. Comins. DOCX document preview.
Chapter 4: Atomic Physics and Spectra
Section: Introduction
1. A clear majority of the information astronomers obtain about distant astronomical objects comes from an analysis of
A) cosmic rays.
B) meteorite fragments.
C) electromagnetic radiation.
D) radioactive decay products.
Section: 4-1
2. When a rod of metal is heated intensely, its predominant color will
A) remain red as the intensity of light increases.
B) change from red through orange to white and then to blue.
C) change from blue through white, then orange, and finally red, when it becomes red-hot at its hottest.
D) be white, all colors mixed together, as the intensity of light increases.
3. Pieces of metal are heated by varying amounts in a flame. The hottest of the pieces will be the one that shows MOST prominently which color?
A) red
B) black
C) yellow
D) blue
4. What changes should an observer expect to see in the resulting spectrum of emitted light from a piece of metal when it is heated slowly in an intense flame from 500 K to 1500 K?
A) The intensity of radiation would increase greatly, while the color would change from blue through white to red.
B) The intensity of radiation would increase greatly, and the color would change from red through white to blue.
C) The intensity of radiation would increase greatly, while the color would remain a dull red.
D) The intensity of radiation would increase only slightly, while the color would change from red through white to blue.
5. Lin Carter, the science fiction writer, once wrote a story entitled The Green Star. Is it possible for a star to be green?
A) Yes. The surface temperature would have to be about 6000 K in order for the spectrum to peak in the green.
B) Yes, but the surface temperature would have to be at least 12,000 K in order to produce enough green to be visible.
C) No. A star cannot become hot enough to have its spectrum peak in the green.
D) No. When a star is hot enough to produce green, it also produces all wavelengths longer than green and also some shorter wavelengths, in roughly equal amounts.
6. Radiant energy shines on a blackbody, raising its temperature and causing it to emit radiation. The spectrum of radiation it emits depends on
A) the spectrum of the radiation it has absorbed.
B) its temperature.
C) its volume.
D) its shape.
7. To a physicist, a blackbody is defined as an object that
A) always emits the same spectrum of light, whatever its temperature.
B) reflects all radiation that falls on it, never heating up and always appearing black.
C) always appears to be black, whatever its temperature.
D) absorbs all radiation that falls on it.
8. An ideal blackbody in physics and astronomy is an object that
A) emits only infrared light and hence appears black to the eye.
B) does not emit or absorb any electromagnetic radiation.
C) absorbs and emits electromagnetic radiation at all wavelengths.
D) absorbs all electromagnetic radiation but emits none.
9. A blackbody is an idealized object in physics and astronomy that
A) reflects no light and emits light in a manner determined by its temperature.
B) reflects and emits radiation in a manner that is completely determined by its temperature.
C) reflects and emits light with the same intensity at all wavelengths.
D) does not emit or reflect any radiation.
10. A perfect blackbody is so named because it
A) reflects all radiation falling upon it but emits none of its own.
B) absorbs all radiation falling upon it and reflects none.
C) never emits radiation.
D) always emits the same amount and color of radiation regardless of its temperature.
11. Two physicists, one on the east coast and one on the west coast of North America, discover that they have constructed ideal blackbodies in their laboratories. The two blackbodies are made from very different materials. Without conducting tests, they know that the radiation emitted by these two objects will be
A) identical if the blackbodies are at the same temperature, but not otherwise.
B) identical if the blackbodies have the same size, even if their temperatures are different.
C) different because the blackbodies were made from different materials.
D) different because the amount of light falling on the blackbodies is likely to be different in the two laboratories.
12. Figure 4-2 in the text shows that a blackbody with a temperature of 3000 K emits radiation that peaks at a wavelength much longer than wavelengths in the visible part of the spectrum. This means that the object
A) is not visible but might be detected with equipment sensitive to nonvisible radiation.
B) emits no radiation, like all blackbodies.
C) emits visible radiation but not as intensely as at longer wavelengths.
D) emits no visible radiation but would emit visible radiation if its temperature were increased.
Section: 4-2
13. An astronomer plots the intensity of the radiation emitted from an opaque, perfectly absorbing object at a certain temperature versus its wavelength. As the temperature increases, the wavelength at which the spectrum peaks becomes shorter and shorter. This is an example of
A) Stephan’s law.
B) Kepler’s first law.
C) Bode’s law.
D) Wien’s law.
4. The amount of radiation emitted by a blackbody depends on all of these properties of the blackbody EXCEPT
A) the wavelength under consideration.
B) the temperature.
C) the chemical composition.
D) the surface area.
15. The total amount of radiation emitted by a heated blackbody depends on its temperature and
A) how much surface area it has.
B) how much volume it has.
C) its color.
D) its chemical composition.
16. Two perfectly absorbing spheres have radii of R and 3R. Both are held at the same temperature. The flux of radiant energy emerging from each square meter of the larger sphere is
A) the same as the flux from the smaller sphere.
B) 3 times the flux from the smaller sphere.
C) 9 times the flux from the smaller sphere.
D) 27 times the flux from the smaller sphere.
17. What overall effect on the visible spectrum of the light from a star results from the light’s passage through Earth’s atmosphere?
A) The intensity of the long wavelength portion of the spectrum is increased.
B) The intensity of the short wavelength portion of the spectrum is reduced.
C) The intensity is reduced uniformly across the spectrum.
D) The long and short wavelength portions of the spectrum are reduced in intensity, but the middle portion is unaffected.
18. If one wants to design a device that will detect animals at night by the radiation they give off, even if the night is totally dark, to what wavelength range should the device be made sensitive?
A) ultraviolet
B) visual, like the human eye
C) No device can detect objects on a totally dark night.
D) infrared
19. The peak wavelength emitted in the spectrum of a blackbody is proportional to what power of the blackbody’s Kelvin temperature?
A) –4
B) –1
C) 1
D) 4
20. To use Wien’s law to find the temperature of an object, one needs to know
A) the object’s distance.
B) the object’s mass.
C) the wavelength in the spectrum of the object at which the intensity is greatest.
D) the frequency of the most energetic photons emitted from the object.
21. The Sun’s spectrum peaks in the yellow-green region (i.e., this region is the most intense part of its spectrum). The spectrum of Rigel (the star in the knee of Rigel) peaks in the short-wavelength end of the visible spectrum. Compared with the Sun, Rigel is
A) cooler and redder.
B) cooler and whiter.
C) hotter and redder.
D) hotter and whiter.
22. An astronomer plots the intensity of the radiation emitted from an opaque object at a certain temperature versus its wavelength. As the object’s temperature increases, the total amount of energy emitted all across the spectrum increases as the fourth power of the temperature. This is an illustration of
A) the Stefan-Boltzmann law.
B) Kepler’s first law.
C) Bode’s law.
D) Wien’s displacement law.
23. An astronomer plots the blackbody curve for an object at 8000 K and then raises the temperature of the object to 12,000 K and plots the blackbody curve again. These curves
A) intersect at a point that depends on the mass of the object.
B) intersect at a point that depends on the atomic structure of the object.
C) intersect at several points. The number of crossings can be used to find the chemical composition of the object.
D) will not intersect.
24. If curves of intensity versus wavelength are plotted for a single object at various temperatures, it is found that the curves never cross. Why is this important?
A) If the curves do not cross, then the object is not a blackbody.
B) The only situation in which the curves do not cross is when the source is a neutron star⎯essentially an atomic nucleus the size of a star.
C) If the curves do not cross it means that monochromatic light has been emitted from the source.
D) Because each curve is unique, in theory it is possible to determine the temperature from a single point on a blackbody curve.
25. The symbol max represents the
A) longest wavelength in a spectrum.
B) wavelength that corresponds to the color of the light.
C) wavelength of the brightest color in the spectrum.
D) wavelength that corresponds to the color of the object that is being heated.
26. The value of max in the spectrum given off by a heated blackbody depends on the object’s
A) size.
B) color.
C) temperature.
D) chemical composition.
27. The ratio of the intensities of two different wavelengths in the spectrum of a blackbody depends on the blackbody’s
A) size.
B) color.
C) temperature.
D) chemical composition.
28. The wavelength at which the spectrum emitted from a blackbody is most intense is proportional to what power of the blackbody’s Kelvin temperature?
A) T
B) 1/T
C) T2
D) T4
29. The total radiant energy emitted per unit area from a blackbody’s surface is proportional to what power of the blackbody’s Kelvin temperature?
A) T
B) 1/T
C) T2
D) T4
30. The total radiant energy emitted from the entire surface of a blackbody is proportional to what power of the blackbody’s Kelvin temperature?
A) T
B) 1/T
C) T2
D) T4
31. In what units does one measure flux F?
A) joule per square meter per second
B) joule per second
C) joule per square meter per second per Kelvin degree
D) joule times square meter per second
32. In what units does one measure luminosity L?
A) joule per square meter per second
B) joule per second
C) joule per square meter per second per Kelvin degree
D) joule times square meter per second
33. An astronomer observes two stars of the same surface temperature, but one has twice the diameter of the other. How many times larger is the energy production rate per unit surface area from the larger star compared with that from the smaller star?
A) 2
B) 4
C) 16
D) They are the same.
34. An astronomer observes two stars of the same surface temperature, but one has twice the diameter of the other. How many times larger is the luminosity from the larger star compared with that from the smaller star?
A) 2
B) 4
C) 16
D) They are the same.
35. Stars A and B have the same radius, but the spectrum of star A peaks at a wavelength of 500 nm, whereas star B’s spectrum peaks at 1000 nm. What is the ratio of the Kelvin temperature of the surface of star A to the Kelvin temperature of the surface of star B?
A)
B) 1/4
1/2
C) 2
D) 4
36. Stars A and B have the same radius, but the spectrum of star A peaks at a wavelength of 500 nm, whereas star B’s spectrum peaks at 1000 nm. What is the ratio of the energy flux leaving the surface of star A to the energy flux leaving the surface of star B?
A) 1/16
B) 1/4
C) 4
D) 16
37. Stars A and B have the same radius, but the spectrum of star A peaks at a wavelength of 500 nm, whereas star B’s spectrum peaks at 1000 nm. What is the ratio of the luminosity of star A to the luminosity of star B?
A) 1/16
B) 1/4
C) 4
D) 16
38. The temperature scale most often used by scientists is the
A) Kelvin scale.
B) Richter scale.
C) Fahrenheit scale.
D) Celsius scale.
39. The hot, dense gas existing on the Sun emits energy
A) only at certain wavelengths and not at other wavelengths.
B) at all wavelengths, with a peak at one particular wavelength (color).
C) mostly at the longest and shortest wavelengths, with a minimum in between.
D) with the same intensity at all wavelengths. Earth’s atmosphere absorbs radiation at both short and long visible wavelengths to produce the observed spectrum.
40. The star Vega has a higher surface temperature than the Sun. With IR indicating infrared and UV indicating ultraviolet, Vega emits _____ IR and _____ UV flux than the Sun.
A) less; more
B) more; more
C) more; less
D) less; less
41. Which of these statements is true if the star Betelgeuse has a lower surface temperature than the Sun? (Assume that IR means infrared radiation and UV means ultraviolet radiation.)
A) Betelgeuse emits more IR and less UV flux than the Sun.
B) Betelgeuse emits more IR and more UV flux than the Sun.
C) Betelgeuse emits less IR and more UV flux than the Sun.
D) Betelgeuse emits less IR and less UV flux than the Sun.
42. If all stars are considered to be perfect blackbodies, then which of these relationships should hold regarding the energy flux, or energy emitted per unit area, from stars?
A) All stars of the same mass emit the same energy flux.
B) All stars of the same temperature emit the same energy flux.
C) All stars of the same composition (made of exactly the same material) emit the same energy flux.
D) All stars of the same distance emit the same energy flux.
43. The Stefan-Boltzmann law, which relates the energy per unit area F emitted by an object to its temperature T, F = T4, is obeyed by what kind of object?
A) red-colored object, which absorbs blue light but reflects red light
B) only hot gases, whose atoms emit and absorb only specific colors (e.g., neon tubes)
C) blackbody, a perfect absorber and emitter of energy at all wavelengths
D) all objects, whatever their color or reflective properties
44. The energy flux, F, emitted by a star is the amount of
A) energy emitted by the entire star each second.
B) incoming light reflected by the star each second.
C) energy emitted by each square meter of the star’s surface each second.
D) energy emitted by the star over its lifetime.
45. Which of these equations represents the dependence of the total energy flux F of radiation emitted per unit area by a blackbody (e.g., star) on its temperature T with a constant?
A) FT4 =
B) F4 = T
C) F = /T
D) F = T4
46. When a blackbody is heated to a temperature T, its total energy flux per second per unit area F at all wavelengths (where is a constant) is given by
A) F = /T2.
B) F = T.
C) FT = .
D) F = T4.
47. By what factor does the total energy emitted per unit time at all wavelengths from an opaque, perfectly absorbing object increase if its temperature increases by a factor of 3 (e.g., approximately from room temperature to 900 K)?
A) 27
B) 3
C) 9
D) 81
48. Two stars, A and B, have the same temperature, but star A is 4 times larger in diameter than star B. Which of these statements about these stars is true?
A) Stars A and B emit the same flux.
B) Stars A and B emit the same total amount of energy per second.
C) Star A emits 4 times the flux that star B emits.
D) Star A emits 16 times the flux that star B emits.
49. Two heated spheres are at the same temperature, but one sphere has twice the radius of the other. The flux emitted from the larger sphere is
A) half the flux emitted from the smaller sphere.
B) the same as the flux emitted from the smaller sphere.
C) twice the flux emitted from the smaller sphere.
D) 4 times the flux emitted from the smaller sphere.
50. What is the difference between “luminosity” and “flux”?
A) Flux is determined by energy in the visible wavelengths only; luminosity is computed all across the spectrum.
B) Luminosity is the rate at which energy is emitted from an entire object; flux is luminosity per unit area.
C) Flux is the rate at which energy is emitted from an entire object; luminosity is flux per unit area.
D) They are the same thing.
51. A piece of iron is heated from 400 K to 800 K. The total energy emitted per second by this iron will increase by a factor of
A) 296.5.
B) 4.
C) 2.
D) 16.
52. The temperature of the surface of the Sun is 5800 K. What would be the surface temperature of a star that emits twice the energy flux (watts per square meter) that the Sun emits?
A) 6900 K
B) 4880 K
C) 11,600 K
D) 8200 K
53. The Sun appears yellow to the eye for a variety of reasons. Which one of these is NOT one of these reasons?
A) The sunlight that passes through Earth’s atmosphere is scattered more strongly in the short wavelengths of blue and green than in the longer wavelengths of yellow.
B) The eye is most sensitive to the yellow-green part of the spectrum.
C) The white light spectrum with blue scattered out looks yellow.
D) The Sun’s blackbody spectrum is sharply peaked in the yellow part of the spectrum.
54. Wien’s law, relating the peak wavelength max of light emitted by a dense object to its temperature T, can be represented by
A) max = constant T4.
B) maxT = constant.
C) max = constant/T2.
D) max/T = constant.
55. The laws governing the energy flux F and wavelength of maximum intensity max of emitted radiation from a hot, dense body whose temperature is T (where and a are constants) are given by
A) F = T, max = a/T4 .
B) F = T4, maxT = a.
C) F = T4, max = aT.
D) F = T2, maxT = a.
56. The wavelength in the middle of the yellow part of the spectrum is 575 nm. What surface temperature would the Sun have if its peak were in the middle of the yellow?
A) 4000 K
B) 5100 K
C) 6000 K
D) 8600 K
57. Cepheid variable stars pulsate regularly in size. During the contraction part of the cycle, when the star’s temperature is increasing, the peak wavelength of the emitted radiation will
A) shift from the visible to the UV part of the spectrum.
B) shift from the UV to the visible part of the spectrum.
C) remain unchanged.
D) change randomly, independent of the temperature changes.
58. As a newly formed star continues to contract, its temperature increases, while the chemical nature of the gas does not change. Which of these could happen to the peak wavelength of its emitted radiation?
A) The peak wavelength will move toward shorter wavelengths (e.g., IR to visible).
B) The peak wavelength will not change because it does not depend on temperature.
C) The peak wavelength will remain constant because the chemical state of the gas does not change.
D) The peak wavelength will move toward longer wavelengths (e.g., visible to IR).
59. As a new star evolves from COOL dust and gas to a HOT star, the peak wavelength of its spectrum of emitted electromagnetic radiation could
A) change from the infrared to the visible wavelengths.
B) change from the ultraviolet to the visible range.
C) increase from the visible to infrared wavelengths.
D) remain the same.
60. When a solid body (or a dense gas such as a star) cools from a temperature of several thousand degrees, the “color” or wavelength of maximum emission of radiation will
A) move initially toward the red end of the spectrum, then move back toward the blue end of the spectrum as the intensity of radiation fades and eventually becomes invisible to the eye.
B) move steadily toward the blue end of the spectrum.
C) remain constant, as it depends only on the original color of the body.
D) move steadily toward the red end of the spectrum.
61. The average temperature of Mars is less than that of Earth. What would be the relative wavelengths of the peak emissions of the spectra from these planets?
A) The emission from the two planets would peak at the same wavelength, but the radiation from Mars would be less intense than that from Earth.
B) The wavelength of peak emission from Earth would be at a longer wavelength than that from Mars.
C) The wavelength of peak emission from Mars would be at a longer wavelength than that from Earth.
D) It is not possible to predict the outcome of this experiment from the information given.
62. What will be the peak wavelength of electromagnetic radiation emitted by a piece of iron that is just melting at a temperature of 1808 K? (Use Wien’s law, which relates the peak wavelength max emitted by a body to its temperature T, and see Figure 4-2) (1 m = 10–6 m).
A) 16 m, intermediate infrared
B) 1.89 m, near infrared
C) 1.6 m, near infrared
D) 1.04 m, very near infrared
63. A star whose surface temperature is 100,000 K will emit a spectrum whose peak wavelength is at
A) ultraviolet wavelengths.
B) X-ray wavelengths.
C) visible wavelengths.
D) infrared wavelengths.
64. If the human eye has evolved over time so that its peak wavelength sensitivity is about 0.5 m (1 m = 10–6 m), what will be the temperature of a blackbody to which the eye will be MOST sensitive?
A) 0.58 K
B) 580 K
C) 5800 K
D) 14,240 K
65. A physicist is asked to design an infrared system to detect human beings (at a normal temperature of 310 K) in darkness. What would the wavelength of peak sensitivity of the equipment need to be?
A) 9.35 m
B) 0.935 m
C) 0.00094 m
D) 90 m
66. What is the approximate peak wavelength of radiation emitted by (live) human beings, who are (normally) at a temperature of about 310 K?
A) 94 m
B) 3.1 m
C) 0.94 m
D) 9.4 m
67. Huge fluxes of X-rays are detected from the direction of Cygnus X-1 with a spectrum that looks similar to that of a blackbody with a peak wavelength of 1.45 nm (1 nm = 10–9 m). These X-rays are probably emitted by matter being heated as it falls into a black hole. What is the temperature of this gas?
A) 2 106 K
B) 4205 K
C) 2 10–2 K
D) 2 104 K
68. A small particle of interplanetary material is heated by friction from a temperature of 400 K to 4000 K as it falls into the atmosphere of Earth and produces a meteor or a shooting star in the sky. If this object behaves like a perfect blackbody over this short time, how will its emitted radiation change as it is heated?
A) The intensity of the radiation will rise by a factor of 100, while the peak wavelength of emitted light will become shorter by a factor of 100, moving from the infrared to the ultraviolet.
B) The intensity of the radiation will rise by a factor of 10,000, while its peak wavelength will become longer by a factor of 10, moving from the visible to the infrared of heat radiation.
C) The emitted intensity of the radiation will rise by a factor of 10,000, while its peak wavelength will become shorter by a factor of 10, from infrared to red visible light.
D) The intensity of the radiation will rise by a factor of 10, while its peak wavelength will become shorter by a factor of 10, moving from the infrared to red visible light.
69. In the revolution that overtook physics around 1900, the assumption that Planck made in order to solve the problem concerning the spectrum of radiation emitted by a hot blackbody was that radiation was
A) emitted as continuous waves whose wavelength was inversely proportional to the temperature of the object.
B) emitted in small, discrete packets or quanta of energy whose individual energies were inversely proportional to the wavelength of the light.
C) emitted in small, discrete packets or quanta of energy, each quantum having an energy directly proportional to the wavelength of the light.
D) made up of small, discrete packets or quanta of energy whose individual energies were all the same, independent of wavelength.
70. The important breakthrough in theoretical physics that was first suggested by Planck to explain the shape of the spectrum of a hot body was the
A) discovery of the formula F = T4, which can be used to calculate the total energy flux emitted by the hot body over all wavelengths.
B) idea that light traveled at a constant speed, whatever the speed of the source.
C) idea that light is a form of electromagnetic energy transmitted at a constant speed and that there is a continuous spectrum of electromagnetic waves from gamma rays to radio waves.
D) concept that electromagnetic energy was emitted in small packets, or quanta.
71. Why does the Sun look red when it is setting?
A) Red is the Sun’s natural color as determined by Wien’s law, but it is only when the Sun is close to the horizon that sunlight can pass through the atmosphere unfiltered.
B) When the Sun is close to the horizon, it is traveling away from the observer at great speed, and the Doppler shift makes it look red.
C) Earth’s atmosphere scatters longer wavelength light more easily than shorter, so more red light is scattered out of the sunlight and into observers’ eyes.
D) Earth’s atmosphere scatters shorter wavelength light more easily than longer, so more red light is left to reach observers’ eyes.
72. Why is the sky blue?
A) The air molecules absorb red light more effectively than blue light, allowing more blue light to reach observers on Earth’s surface.
B) The air molecules scatter blue light more effectively than red light, so more blue light reaches observers on Earth’s surface indirectly (from directions other than the direct beam of sunlight).
C) The air molecules scatter red light more effectively than blue light, so less red light reaches observers on Earth’s surface indirectly (from directions other than the direct beam of sunlight).
D) The air molecules absorb blue light more effectively than red light, making the sky appear bluer.
Section: 4-3
73. If a certain gas is heated and observed through a grating, a bright line spectrum will be seen. If instead a source of continuous spectrum shines through a cooler sample of this same gas, a dark absorption spectrum is observed. How do the positions of the lines in these two spectra compare?
A) All the lines in the spectrum from the hot gas will be at higher frequencies than the corresponding lines in the spectrum of the cooler gas.
B) All the lines in the spectrum from the hot gas will be at lower frequencies than the corresponding lines in the spectrum of the cooler gas.
C) The lines in the two spectra will be at the same frequencies. They will be the same spectra.
D) These two processes produce spectra by completely different means, and there will be no relationship at all between the two spectra.
74. The light from a small amount of a particular chemical element, when heated in a flame, is found to consist of a
A) pattern of narrow, bright emissions at wavelengths that are specific to the element and different for each element.
B) continuous spectrum of light from which certain colors are missing or absorbed, as the absorbed colors are different for different elements.
C) pattern of narrow, bright emissions at specific wavelengths that are the same for all elements, except the relative intensities of the lines differ for different elements.
D) continuous spectrum of light whose peak wavelength is specific to the particular element.
75. The lines Fraunhofer saw in his solar spectrum were
A) absorption lines.
B) emission lines.
C) bright lines.
D) continuum lines.
76. Which very significant fact concerning the spectra produced by hot gases, such as elements heated on the solar surface (Fraunhofer, with the solar spectrum) or in a flame (Bunsen and Kirchhoff, with laboratory spectra), was discovered in the 1800s?
A) Each chemical element produces its own characteristic pattern of spectral lines that remains fixed as the temperature increases.
B) Chemical elements emit spectral lines that move continuously toward the blue end of the spectrum as the gas temperature increases.
C) The higher the temperature, the greater the redshift of the emitted spectral lines.
D) Every chemical element produces the same set of spectral emission or absorption lines as every other chemical element, but their relative emission intensities differ.
77. The chemical makeup of a star’s surface is usually inferred by
A) theoretical methods, considering evolution of the star.
B) spectroscopy of the light emitted by the star.
C) measuring the chemical elements present in the solar wind.
D) taking a sample of the star’s surface with a space probe.
78. Where and by what technique was the element helium first discovered?
A) in radioactive rocks, by radioactive measurements of uranium deposits
B) on the Sun, from spectroscopy during a solar eclipse
C) in the laboratory, by examining the spectrum of heated chemicals in a flame
D) in the upper atmosphere of Earth, by studying the spectrum of the aurora, or northern lights
79. The element helium was first discovered and identified as a separate element
A) in natural gas originating underground, from the spectrum emitted from a flame of burning natural gas.
B) in rocks containing radioactively decaying elements such as uranium.
C) on the Sun, from the emitted spectrum from its upper atmosphere.
D) inside meteorites that had come from outer space.
80. What property of helium allowed scientists to first discover its existence?
A) Helium accumulates inside meteoroids (fragments of rock and iron orbiting the Sun that, when they fall to Earth, are known as meteorites).
B) Helium refuses to combine chemically with other elements.
C) Helium absorbs light at certain wavelengths that were not characteristic of any element known at that time.
D) Helium is characteristically found in rocks containing radioactively decaying elements such as uranium.
81. A spectrograph is a scientific instrument that
A) measures the effectiveness of the specular reflection of mirrors.
B) spreads out light from a source into its component colors, or spectrum.
C) measures the transparency of different types of glass at different colors by using glass prisms.
D) focuses all the colors of light from a star at one point so that the total intensity of the star can be measured, for photometry.
82. When light passes through a prism of glass, the
A) different colors or wavelengths of light are separated in angle by the prism.
B) different colors are caused by multiple reflections in the prism and interference between the resulting beams.
C) prism absorbs colors from different parts of the broad beam coming out of the prism, leaving the complementary colors observed.
D) prism adds colors to different parts of the broadly scattered beam coming out of it.
83. One problem with using a glass prism to produce a spectrum from white light is that
A) glass absorbs almost all of the infrared in the white light.
B) glass absorbs almost all of the ultraviolet in the white light.
C) blue and violet do not spread out very much as a result of passing through the prism.
D) red is absorbed more than is the rest of the spectrum.
84. Which of these items is considered to be the BEST one to use in a spectrograph to disperse light into its spectrum of colors?
A) CCD array
B) diffraction grating
C) glass prism
D) two-element achromatic lens
85. What is a diffraction grating?
A) flat, rectangular array of closely spaced photosensitive cells
B) piece of glass with thousands of closely spaced, parallel grooves
C) array of many radio telescopes used to observe a single source simultaneously
D) triangular prism of solid glass used to disperse light into its colors
86. A particular spectrograph, used by an astronomer to disperse light into its colors, contains a piece of glass that has been ruled with thousands of closely spaced, parallel lines. What is the name of this piece of glass?
A) interferometer
B) CCD array
C) diffraction grating
D) prism
87. Which of these points is NOT a characteristic of a prism when used in a spectrograph?
A) A prism causes different light rays to interfere with each other.
B) A prism absorbs light unevenly over the spectrum (over the different colors).
C) A prism does not pass ultraviolet light.
D) A prism spreads the light out unevenly in wavelength.
88. What evidence exists that the Sun contains the element iron?
A) Solar spectra show absorption in spectral lines that are characteristic of iron and are unique to it.
B) The peak wavelength of the continuum spectrum of sunlight is characteristic of the emission spectrum of iron, as seen when a piece of iron is heated in the laboratory.
C) Scientists have collected meteorites composed of almost pure iron that originated in the Sun.
D) Magnetic fields exist in sunspots and on the Sun, and they must be produced by iron in the same way that Earth’s magnetic field is generated.
89. The spectrum of the Sun
A) is a continuous spectrum without any absorption lines.
B) would show no absorption lines if the spectrum were taken from aboard a spacecraft above Earth’s atmosphere.
C) contains absorption lines due to Earth’s atmosphere as well as the Sun’s outer atmosphere.
D) contains many bright emission lines as well as absorption lines.
90. When astronomers look for evidence of hydrogen gas in the spectra of the Sun, the planets, or the nearby stars, the positions of the spectral features or “lines” due to hydrogen are in
A) a pattern in which the positions of the lines depend on the temperature of the source.
B) the same pattern for the Sun and for planetary sources but very different for stars at larger distances because of absorption of light by the interstellar matter.
C) the same characteristic pattern as seen in the laboratory, a pattern unique to hydrogen.
D) a pattern that depends on the location of the planet or star and that can be reproduced only with difficulty in the laboratory.
91. The spectrum of sunlight, when spread out by a spectrograph, has which characteristic appearance?
A) continuous band of color, crossed by innumerable emission lines
B) continuous band of color, crossed by innumerable dark absorption lines
C) series of separate emission lines, characteristic of many elements, that overlap in certain regions of the spectrum to produce short continuum segments
D) continuous and uniform band of color from violet to deep red
92. Spectral lines are of particular importance in astronomy because
A) each different element has a characteristic line spectrum.
B) they can be observed through a diffraction grating.
C) they are the only light bright enough to be seen over long distances.
D) only stars produce bright line spectra.
Section: 4-4
93. The dark absorption lines in the solar spectrum are caused by
A) a cooler layer of gas overlying the hot solar surface, which contains many elements, including hydrogen, helium, magnesium, calcium, and iron.
B) a cooler layer overlying the hot solar surface, consisting solely of hydrogen gas, which produces all the absorption lines.
C) absorption by atoms and molecules in Earth’s cool atmosphere.
D) a hotter layer of gas that overlies the cooler solar surface and produces the absorption lines.
94. Atoms in a thin, hot gas (such as a neon advertising sign), according to Kirchhoff’s laws, emit light at
A) specific wavelengths or colors in a pattern that depends on the element.
B) only visible wavelengths.
C) all wavelengths, the shape of the continuum spectrum depending on the temperature of the gas.
D) only one specific wavelength or color.
95. A spectrum produced by heating a gaseous sample of a single element consists of a series of bright lines. If a solid composed of this element is heated, the result will be that
A) the same pattern of bright lines will occur, only brighter.
B) the same pattern of bright lines will occur, only dimmer.
C) a continuous spectrum will be formed.
D) a continuous spectrum will be formed with deep absorption lines at the same places as the bright lines in the spectrum of the gas.
96. An astronomer has a sample of a rarified gas. What kind of spectrum can it produce?
A) It can only produce an emission line spectrum.
B) It could produce an emission line spectrum, or it could produce an absorption line spectrum if placed in front of a bright continuous source.
C) It could not produce a continuous spectrum even if condensed, liquefied, or solidified.
D) It can only produce an absorption line spectrum.
97. An astronomer finds a source of light in space that emits light only in specific, narrow emission lines. Kirchhoff’s laws lead him to which conclusion?
A) The source cannot consist of gases but must be a solid object.
B) The source is made up of a hot, dense gas.
C) The source is made up of a hot, low-density gas.
D) The source is made up of a hot, dense gas surrounded by a rarefied gas.
98. The gas in the interstellar space between stars is very tenuous (thin) but can be heated to a very high temperature in the vicinity of a hot star. This hot, tenuous gas will emit
A) light at certain wavelengths only (spectral lines), the wavelength of a given spectral line depending on the gas temperature.
B) light at certain wavelengths only (spectral lines), the wavelength of the lines being independent of gas temperature.
C) light at all wavelengths, the continuous spectrum peaking at a certain wavelength or color depending on temperature.
D) no light at any wavelength because hot thin gases do not emit light.
99. Interstellar space (the space between the stars) is filled with extremely low-density hydrogen gas. In the vicinity of a hot star, this gas can be heated to a very high temperature. This hot, low-density gas will
A) emit light at specific wavelengths characteristic of hydrogen, among other elements.
B) emit light at all wavelengths in a blackbody spectrum, with emission lines characteristic of hydrogen superimposed on the spectrum.
C) emit light at all wavelengths in a blackbody spectrum characteristic of a hot gas.
D) reflect light at specific wavelengths characteristic of hydrogen.
100. Atoms in a low-density, hot gas (e.g., in a fluorescent lamp or a neon tube) emit a spectrum that is
A) a series of emissions at specific colors whose wavelengths change in position as the gas temperature is changed.
B) a series of emissions at certain wavelengths that are the same for all atoms but vary with temperature.
C) a series of specific colors unique to the type of atom in the tube but fixed in position when the gas temperature changes.
D) continuous over all visible wavelengths, with maximum intensity in the red.
101. If light from a hot, dense star passes through a cool cloud of gas,
A) the atoms of the gas cloud will add energy to the overall spectrum, enhancing it at specific wavelengths to produce emission lines.
B) the cool gas will not affect the spectrum of the star because cool atoms cannot absorb light.
C) the whole spectrum will be reduced in intensity.
D) only specific wavelengths of light will be removed from the spectrum.
102. According to Kirchhoff’s laws, the continuous spectrum of light from a hot star, after passing through a cool gas cloud,
A) is enhanced at infrared wavelengths by a continuous spectrum emitted by the cool gas.
B) contains additional emission lines from energy emitted by the atoms of the cool gas.
C) shows absorption features where light has been absorbed by the atoms of the cool gas.
D) is unaffected because atoms in the gas cloud are too cool to absorb or emit energy.
103. The star P Cygni (in the constellation Cygnus, the Swan) is surrounded by an extensive low-density atmosphere. It has a bright, continuous spectrum with many narrow, dark absorption lines and a few bright emission lines. The bright, continuous part of the spectrum is produced by
A) only the part of the low-density atmosphere that is between Earth and the surface of the star.
B) the low-density atmosphere of the star emitting light in all directions.
C) all parts of the star, the stellar surface, and the atmosphere, equally.
D) the hot, dense, opaque gas of the star’s surface.
104. The star P Cygni (in the constellation Cygnus, the Swan) is surrounded by an extensive low-density atmosphere. It has a bright, continuous spectrum with many narrow, dark absorption lines and a few bright emission lines. The dark absorption lines are produced by
A) the part of the low-density atmosphere that is between Earth and the surface of the star.
B) the hot, low-density atmosphere of the star emitting light in all directions.
C) all parts of the star, the stellar surface, and the atmosphere, equally.
D) the hot, dense, opaque gas of the star’s surface.
105. The star P Cygni (in the constellation Cygnus, the Swan) is surrounded by an extensive low-density atmosphere. It has a bright, continuous spectrum with many narrow, dark absorption lines and a few bright emission lines. The bright emission lines are produced by
A) the low-density atmosphere of the star emitting light in all directions.
B) only the part of the low-density atmosphere that is between Earth and the surface of the star.
C) all parts of the star, the stellar surface, and the atmosphere, equally.
D) the hot, dense, opaque gas at or near the star’s surface.
106. A hydrogen atom in a low-density, hot gas gives off what type of spectrum?
A) series of emission lines at uniform wavelength spacings
B) uniform spectrum crossed by numerous dark absorption lines
C) series of emission lines spaced in a mathematical sequence
D) uniform spectrum containing all colors
107. The sodium D lines are a closely spaced pair of spectral lines in neutral sodium. They are present as absorption lines in the spectrum of the Sun’s photosphere because of traces of sodium there. What would one expect to see if sunlight is passed through a cool sodium vapor in the laboratory and then observed with a spectroscope?
A) The sodium D lines will become brighter.
B) The sodium D lines will become darker.
C) The two absorption lines will merge into a single line.
D) The position of the sodium D lines will shift to a lower frequency.
Section: 4-5
108. What is a neutron?
A) uncharged atom
B) uncharged particle similar in mass to a proton
C) uncharged atomic nucleus
D) uncharged particle similar in mass to an electron
109. The New Zealand physicist Lord Rutherford and his colleagues in England demonstrated the existence of the very small but massive nucleus inside every atom in which crucial experiment?
A) deflection and occasional reflection backward of energetic nuclear particles in a beam aimed at a thin metal sheet
B) measurement of the spectrum of light emitted from a thin, heated metal sheet
C) detection of the motion of electrons around the nucleus by the use of a very powerful microscope
D) emission of electrons from a metal surface illuminated with UV light
110. The basic makeup of an atom is
A) small negatively charged particles orbiting around a central positive charge.
B) negative and positive charges mixed uniformly through the volume of the atom.
C) miniature planets, possibly with miniature people, gravitationally bound in orbits around a miniature star.
D) small positively charged particles orbiting around a central negative charge.
111. An atom consists of
A) negatively charged electrons moving around a very small but massive, positively charged nucleus.
B) neutrons orbiting an electrically neutral nucleus composed of protons and electrons.
C) positive protons, neutral neutrons, and negative electrons orbiting a small but massive black hole.
D) negatively charged electrons and positively charged protons mixed uniformly throughout the volume of the atom.
112. An atom is now known to consist of a
A) positively charged crystal structure with electrons moving within it.
B) small, positively charged black hole with electrons held in orbits around it by intense gravitational forces.
C) uniform distribution of positively charged matter with electrons embedded in it.
D) small, massive, electrically charged core surrounded by electrons.
113. The physical force that holds the components of an atom together is the
A) nuclear force between protons and neutrons.
B) gravitational force between the massive nucleus and the much less massive electrons.
C) centrifugal force produced on electrons by their orbital motion around the nucleus.
D) electromagnetic attraction between the positive nucleus and the negative electrons.
114. The force that holds the atomic nucleus together is
A) gravitational.
B) electrical.
C) weak nuclear.
D) strong nuclear.
115. Which of these is NOT one of the four fundamental forces in nature?
A) strong nuclear
B) gravitational
C) friction
D) electromagnetic
116. Isotopes of a particular element in the periodic table have the same number of _____ in the nucleus.
A) neutrons but different numbers of protons and electrons
B) protons but different numbers of neutrons
C) neutrons but different numbers of protons
D) protons and neutrons
117. The age of the solar system has been dated rather precisely to 4.57 billion years. What method was used to determine this number?
A) calculating the age of the Sun
B) calculating the age of Earth by counting layers of geologic deposits
C) determining the age of the Moon, which is older than Earth, by measuring the density of craters
D) determining the age of meteorites by radioactive dating
118. Two different isotopes of the element selenium will have the same number of
A) protons but a different number of neutrons.
B) protons but a different number of electrons.
C) protons and neutrons, but they are arranged differently in the nucleus.
D) neutrons but a different number of protons.
119. Which of these are isotopes of carbon?
A) C I and C III
B) 12C and 14C
C) CH3 and CH4
D) CH4 and C2H4
120. One nucleus that will prove to be important in the study of the evolving universe is 56Fe. This isotope of iron has 26 electrons as a neutral atom. The nuclear isotope has
A) 26 protons and 56 neutrons.
B) 26 protons and 30 neutrons.
C) 56 protons and 26 neutrons.
D) 56 protons and 30 neutrons.
121. One isotope of iron has an atomic number of 26. How many protons are there in its nucleus?
A) The atomic number is not related to the number of protons in the nucleus, which could be any number between 1 and 26.
B) 1 less than 26, or 25
C) 26
D) 56
122. How do the nuclei of the isotopes 14C of carbon and 14N of nitrogen differ from each other?
A) The nuclei have the same number of protons but a different number of neutrons.
B) The nuclei are identical; the isotopes differ only in the number of electrons.
C) The nuclei have different numbers of both protons and neutrons.
D) The nuclei have the same number of neutrons but a different number of protons.
123. The carbon isotope 14C is not useful for most radioactive dating in astronomy because
A) it is not radioactive.
B) it is too rare.
C) its half-life is too short.
D) its half-life is too long.
124. Iron has 26 protons, and one isotope of iron, 57Fe, has an atomic mass of about 57. How many neutrons are in the nucleus of this atom?
A) 31
B) 83
C) 26
D) 57
125. How many electrons surround the nucleus of a neutral atom of the isotope 18O of oxygen? Oxygen has an atomic number of 8.
A) 18
B) 7
C) 10
D) 8
126. How many electrons surround the nucleus of a neutral atom of iron, which has an atomic number of 26?
A) 26
B) 27
C) 52
D) 25
127. The isotope 15N has an atomic number of 7. The nucleus of this isotope contains
A) 7 protons and 8 neutrons.
B) 7 neutrons and 15 protons.
C) 7 protons and 15 neutrons.
D) 7 neutrons and 8 protons.
128. The isotope 20Ne has an atomic number of 10. The nucleus of this isotope contains _____ protons and _____ neutrons.
A) 9; 11
B) 20; 20
C) 11; 9
D) 10; 10
129. The atomic number of the isotope 238U of uranium is 92. The nucleus of this isotope contains
A) 92 protons and 146 neutrons.
B) 92 protons, 54 neutrons, and 92 electrons.
C) 184 protons, 92 electrons, and 54 neutrons.
D) 146 protons and 92 neutrons.
130. What is the total number of protons and neutrons in the nucleus of an atom of the fissionable isotope of uranium used in nuclear weapons, 235U, which has an atomic number of 92?
A) 235
B) 92
C) 143
D) 327
131. Which of these properties of the isotopes 15N (nitrogen) and 15O (oxygen) are very nearly the same?
A) number of protons in the nucleus
B) number of neutrons in the nucleus
C) nuclear mass and number of neutrons in the nucleus
D) nuclear mass
132. Considering the oxygen isotopes 15O and 16O, which of these properties is/are very nearly the same for both isotopes?
A) number of protons in the nucleus
B) mass of the nucleus
C) nuclear mass and number of neutrons in the nucleus
D) number of neutrons in the nucleus
133. If one neutron is added to a nucleus of an isotope of carbon, 12C, in a particular nuclear reaction, the result will be
A) 11C.
B) 13C.
C) 12O.
D) 13O.
134. When an atom of the radioactive carbon isotope 14C decays into 14N (nitrogen), what happens in the nucleus of the atom?
A) The nucleus of the carbon atom captures a nucleus of a hydrogen atom (a proton).
B) A proton is ejected from the nucleus.
C) A neutron becomes a proton.
D) A neutron is ejected from the nucleus.
135. Of the four combinations of particles that form the nuclei of atoms, which one does NOT make up the nucleus of an isotope of the same element as the other three?
A) 7 protons, 9 neutrons
B) 8 protons, 10 neutrons
C) 8 protons, 9 neutrons
D) 8 protons, 8 neutrons
136. What is the half-life of a sample of matter containing a radioactive element?
A) time needed for the radioactive atoms to build up half the energy needed to decay
B) half the time needed for the radioactive decay rate to double
C) time needed for half the radioactive atoms in the sample to decay
D) half the time needed for all the radioactive atoms in the sample to decay
137. Suppose that a particular sample of wood contains 1020 atoms of the radioactive isotope 14C. The half-life of 14C is about 6000 years. Approximately how long will it take for all the 14C atoms to decay to 14N?
A) infinite amount of time
B) 12,000 years
C) 3000 years
D) 6000 years
138. Carbon-14 (14C) has a half-life of approximately 6000 years. A researcher investigating a piece of ancient wood determines that there is only 1/4 as much 14C present in the wood now as there was when the tree that the wood came from was alive. How old is the piece of wood?
A) 12,000 years
B) The age cannot be determined from this information.
C) 9000 years
D) 24,000 years
139. Suppose that at some time a particular sample of radioactive material contains N radioactive atoms (e.g., N might be 1 billion radioactive atoms). How many radioactive atoms will be left after 3 half-lives have passed?
A) 1/6 N
B) 1/8 N
C) 0
D) 1/2 N
140. Element A decays into element B with a half-life of 700 million years. An astronomer finds a rock that she knows was formed originally without any B present. But the rock now contains both A and B, with the A+B portion of the rock being 1/8 A and 7/8 B. How old is the rock?
A) 350 million years
B) 700 million years
C) 1.4 billion years
D) 2.1 billion years
141. The person who discovered the atomic nucleus was the
A) Swiss mathematician Johann Balmer.
B) Danish physicist Niels Bohr.
C) New Zealand physicist Sir Ernest Rutherford.
D) German optician Joseph von Fraunhofer.
142. Which one of these processes results in an ionized atom?
A) A single proton has been removed.
B) A single proton has been added.
C) An electron has been removed.
D) A proton in its nucleus has been replaced by an electron.
143. An atom in which one or more electrons has been removed is known as a(n)
A) molecule.
B) excited atom.
C) isotope.
D) ion.
144. Ionization of an atom occurs when
A) an electron is removed from the atom.
B) the nucleus is split, or fission occurs.
C) an electron is lifted from the ground state to an excited level.
D) an electron drops from a higher energy level to the ground state.
145. An ionized hydrogen atom is simply a(n)
A) proton.
B) helium nucleus.
C) neutron.
D) electron.
146. The overall charge of a singly ionized neon atom Ne, whose position in the periodic table (or atomic number) is 10, in units of electron charge, is
A) +9.
B) –1.
C) +1.
D) +10.
147. O III is
A) 4-times-ionized oxygen (an oxygen atom that has lost 4 electrons).
B) doubly ionized oxygen (an oxygen atom that has lost 2 electrons).
C) an oxygen isotope with 3 neutrons.
D) 3-times-ionized oxygen (an oxygen atom that has lost 3 electrons).
148. S IV is
A) 4-times-ionized sulfur (a sulfur atom that has lost 4 electrons).
B) 5-times-ionized sulfur (a sulfur atom that has lost 5 electrons).
C) a sulfur isotope with 4 neutrons.
D) 3-times-ionized sulfur (a sulfur atom that has lost 3 electrons).
149. How do the nuclei of the carbon ions C III and C IV differ from each other?
A) The nuclei of the carbon ions C III and C IV have the same number of neutrons but a different number of protons.
B) The nuclei of the carbon ions C III and C IV have different numbers of both protons and neutrons.
C) The nuclei of the carbon ions C III and C IV are identical.
D) The nuclei of the carbon ions C III and C IV have the same number of protons but a different number of neutrons.
150. How many electrons orbit the nucleus of a singly ionized oxygen atom? The atomic number of oxygen is 8.
A) 7
B) 6
C) 9
D) 8
151. How many electrons surround the nucleus of a triply ionized magnesium atom, Mg IV? The atomic number of magnesium is 12.
A) 9
B) 12
C) 11
D) 15
152. In his scattering experiment, Ernest Rutherford expected that the alpha particles he was using as bullets would easily penetrate his gold foil target with no backscatter. What was the actual result of the experiment?
A) It was as expected⎯no backscattered alpha particles.
B) Surprisingly, all of the alpha particles were scattered back from the foil without penetrating.
C) About half of the alpha particles were backscattered.
D) Almost all of the alpha particles penetrated the foil, but a few were backscattered into the direction from which they had come.
153. The majority of the mass of ordinary matter resides in the
A) electrons and the nuclei, shared about equally.
B) electromagnetic energy stored in the atom, from E = mc2.
C) nuclei of atoms.
D) electron clouds around the nuclei of atoms.
Section: 4-6
154. The specific colors of light emitted by an atom in a hot, thin gas (e.g., in a neon tube, a fluorescent bulb, or a gas cloud in space) are caused by
A) an electron dropping into the nucleus, producing small nuclear changes.
B) electrons jumping to lower energy levels, losing energy as they do so.
C) protons jumping from level to level.
D) vibrations of the electrons within the atom.
155. The diameter of the nucleus of an atom, compared to the overall diameter of the atom, is
A) about 99%.
B) 1/10,000.
C) 1/10.
D) 1/2,000.
156. The diameter of the nucleus of a typical atom is
A) 10–4 of the diameter of the atom.
B) 10–3 of the diameter of the atom.
C) 1/2000 of the diameter of the atom.
D) about half of that of the atom.
157. Compared to the mass of an electron, the mass of a proton is
A) almost 2000 times greater.
B) about twice as large.
C) about the same.
D) about 1/2000 as large.
158. The proton, the nucleus of the hydrogen atom, has a mass that exceeds that of the electron by approximately what factor?
A) 2000 times
B) 2 times
C) 100 times
D) 104 times
159. How much heavier is a typical hydrogen atom than a proton?
A) twice as heavy
B) 1 part in 2000
C) 2000 times heavier
D) A hydrogen atom is lighter than a proton.
160. The mass of the proton, the nucleus of the hydrogen atom, exceeds the mass of the electron by approximately what factor?
A) 2000 times
B) 10,000 times
C) 100 times
D) 2 times
161. The neutron is the electrically neutral particle that, along with the proton, makes up the atomic nucleus. The mass of the neutron, compared with that of the proton, is
A) 1/2000 as large.
B) 2000 times greater.
C) about 1/10 as large.
D) about the same.
162. The mass of the electrically neutral particle, the neutron, which is one component of the atomic nucleus along with the proton, is _____ the mass of the proton.
A) about twice
B) about the same as
C) 2000 times less than
D) 200 times greater than
163. In the hydrogen atom, light is emitted whenever an electron
A) jumps from a lower to an upper energy level or orbit.
B) reverses its direction of motion in its orbit.
C) jumps from an upper to a lower energy level or orbit.
D) spirals into the nucleus.
164. In a simple atom, the electrons making transitions between the outermost energy levels and the innermost energy levels give rise to photons with the
A) reddest colors.
B) highest speeds.
C) longest wavelengths.
D) highest energies.
165. Electrons in atoms
A) occupy levels whose energies are fixed.
B) can have any energy.
C) cannot interact with light.
D) can only absorb light.
166. Consider a set of electrons undergoing transitions between energy levels. In the resulting bright line spectrum, the line with the shortest wavelength is produced by the transitions between which of these states?
A) highest to middle
B) highest to lowest
C) lowest to highest
D) middle to lowest
167. Emission spectra from interstellar gas clouds glow with a variety of colors. Red usually indicates hydrogen, and green is usually a characteristic of
A) helium.
B) oxygen.
C) carbon.
D) uranium.
168. The specific sequence of spectral line series emitted by excited hydrogen atoms, in order of decreasing energy of the lowest energy transition, is
A) Balmer, Lyman, Paschen.
B) Lyman, Paschen, Balmer.
C) Lyman, Balmer, Paschen.
D) Paschen, Balmer, Lyman.
169. Atoms of hot hydrogen gas will emit the Balmer series of spectral lines at visible wavelengths when the electrons fall from all higher atomic energy levels to the
A) ionization level, or n = infinity.
B) next level down for each level (e.g., n = 4 to n = 3).
C) first excited level, n = 2.
D) ground state, n = 1.
170. The Balmer series of visible spectral emissions from hydrogen gas arises from transitions in which electrons jump between energy levels
A) from all levels to the ground state, n = 1.
B) from higher levels to the second excited level, n = 3.
C) between adjacent levels (e.g., n = 2 to n = 1, n = 3 to n = 2, n = 4 to n = 3, etc.).
D) from higher levels to the first excited level, n = 2.
171. When electrons jump from higher levels in hydrogen atoms to the level n = 2, the resulting spectrum will consist of a
A) continuum of light with a maximum in the visible spectral range.
B) series of UV lines, the Lyman series.
C) series of IR spectral lines, the Paschen series.
D) series of spectral lines, some of which are in the visible range, the Balmer series.
172. The most intense lines in the Lyman and Balmer series emitted from the hydrogen atom are in what part of the electromagnetic spectrum?
A) ultraviolet
B) visible
C) infrared
D) radio
173. Light that originates in hydrogen atoms in which electrons have jumped from high levels to the level n = 2 will be part of which series of spectral lines?
A) Lyman
B) Balmer
C) There would be a continuum of light, not a series of lines.
D) Paschen
174. Hydrogen gas is heated to the point at which there are electrons at atomic energy levels up to the n = 3 level. When electrons return to the ground state, what possible emission lines from which spectral sequences will result? See Figure 4-11.
A) Paschen (IR), Balmer (visible), and Lyman (UV) series
B) Lyman (UV) series only
C) Balmer (visible) series only
D) Balmer (visible) and Lyman (UV) series
175. The sequence of ultraviolet emission lines emitted by hot hydrogen gas is known as the _____ series.
A) Paschen
B) Planck
C) Lyman
D) Balmer
176. The Lyman series of ultraviolet spectral emission lines from hydrogen gas is produced by electrons jumping
A) to the first excited level from all higher levels.
B) to the ground state from all other energy levels.
C) between adjacent energy levels, n = 2 to n = 1, n = 3 to n = 2, n = 4 to n = 3, and so on.
D) from the continuum level to all other levels.
177. The strong red spectral line emitted by hot hydrogen gas is known as the _____ line.
A) 21-cm
B) Balmer
C) Lyman
D) Paschen
178. If a continuous spectrum of ultraviolet radiation passes through a tube of cool hydrogen gas, what happens to its spectrum?
A) All the radiation passes unhindered except the Lyman L wavelength, which is absorbed by the atoms.
B) Some of the radiation at all wavelengths is absorbed, reducing the intensity at all wavelengths uniformly.
C) All the radiation passes through the tube unhindered because the hydrogen gas is cool and cannot absorb energy.
D) All the radiation passes through the tube unhindered except at the specific wavelengths of the Lyman series, L, L, and so on, which are absorbed by the atoms.
179. Where does the Paschen series of spectral lines from hydrogen gas appear in the electromagnetic spectrum?
A) radio range, with wavelengths longer than 0.01 m or 10 mm
B) ultraviolet region, with wavelengths between 90 nm and 130 nm
C) infrared, with wavelengths longer than 700 nm
D) visible region, with wavelengths between 350 nm to 660 nm
180. The series of spectral absorption lines in the infrared part of the spectrum, known as the Paschen series, results from atomic transitions in hydrogen atoms in which electrons are lifted from which energy level to all higher atomic energy levels?
A) n = 1 level, the ground state, because all series start here
B) n = 3 level
C) ionization level
D) n = 2 level
181. The series of spectral absorption lines in the infrared part of the spectrum that result from atomic transitions in hydrogen atoms in which electrons are lifted from the n = 3 level to all other atomic energy levels is known as
A) ionization transitions.
B) the Lyman series.
C) the Paschen series.
D) the Balmer series.
182. An electron is in the n = 3 energy level in a hydrogen atom. To ionize this atom, it is necessary for the electron to gain a minimum of how much energy? See Figure 4-11.
A) 1.5 eV
B) 4.5 eV
C) 12.1 eV
D) 13.6 eV
183. An electron is in the n = 3 energy level in a hydrogen atom. What can be said about the spectral series in which it can participate by making a single atomic transition?
A) If the electron gains energy, it can participate in the Lyman series; if it loses energy, it can participate in the Balmer series.
B) If the electron gains energy, it can participate in the Lyman series or the Paschen series; if it loses energy, it can participate in the Balmer series.
C) If the electron gains energy, it can participate in the Balmer series; if it loses energy, it can participate in the Paschen series.
D) If the electron gains energy, it can participate in the Paschen series; if it loses energy, it can participate in the Lyman series or the Balmer series.
184. According to modern atomic theory, light emitted by atoms originates from
A) photons emitted directly from the nucleus.
B) transitions of electrons between electron levels of the same atom.
C) collisions between atoms.
D) electrons emitted from the nucleus.
185. The orbits of electrons in an atom are sometimes compared to the orbits of the planets around the Sun. However, only one of these characteristics of electron orbits is shared with planetary orbits. Which one?
A) Larger orbits are associated with higher energies.
B) The particle motions must be described by quantum mechanics.
C) Only certain allowed orbits exist with certain allowed energies and allowed distances.
D) The orbiting particles exhibit both particle and wave properties.
Section: 4-7
186. Because of the Doppler effect, the sound of the engines of an aircraft that flies past an observer
A) changes from a high pitch or frequency to a lower pitch as the plane passes the observer.
B) changes from a low pitch or frequency to a higher pitch as the plane passes the observer.
C) remains at the same pitch or frequency, but the intensity rises as the plane approaches and then falls as the plane moves away.
D) starts at a high pitch or frequency, drops to a low frequency when the plane is overhead, then rises again as the plane moves away.
187. The Doppler effect is the change in the wavelength of light caused by the source
A) being in a high gravitational field.
B) being embedded in a cloud of dust and gas.
C) being in an intense magnetic field.
D) moving with respect to the observer.
188. The observed change in the wavelength of light due to the Doppler effect occurs
A) only when the temperature of an object changes.
B) only when the light source has proper motion (i.e., motion across the line of sight).
C) whenever the light source is moving with respect to the observer (regardless of direction).
D) only when the light source has a radial velocity (i.e., motion toward or away from the observer).
189. The Doppler effect is the
A) change in the wavelength of peak emission of light when the source temperature changes.
B) increase in the observed wavelength of light if the source of light is moving away from you.
C) increase in the observed wavelength of light if the light source is moving toward you.
D) splitting of spectral lines into two or more wavelengths because the source of the light is in a strong magnetic field.
190. An object is observed to show no Doppler shift. As a result, only one of these statements cannot describe the motion of the object. Which one?
A) The object is stationary.
B) The object has only a transverse motion.
C) The object has only a proper motion.
D) The object has only a radial motion.
191. Two objects are moving directly away from an observer at the same speed. One object, however, is twice as far away as the other. How do their Doppler shifts compare?
A) They are the same.
B) The more distant object has the greater Doppler shift.
C) The more distant object has the smaller Doppler shift.
D) Whichever object is larger will have the greater Doppler shift.
192. According to the Doppler effect,
A) spectral lines are split into two or more wavelengths when the source of the light is in a strong magnetic field.
B) the wavelength of light is shifted to a longer wavelength if the source of the light is moving toward the observer.
C) the wavelength of peak emission of light from a source changes as the temperature of the source changes.
D) the wavelength of light is shifted to a shorter wavelength if the source of light is moving toward the observer.
193. The spectrum of a star shows a set of dark absorption lines equivalent to the absorption lines of the Sun but with one exception: Every line appears at a slightly longer wavelength, shifted toward the red end of the spectrum. What conclusion can be drawn from this observation?
A) A cloud of cold gas and dust surrounds the star and is absorbing light from it.
B) The star is moving toward Earth.
C) The temperature of the star’s surface is higher than that of the Sun.
D) The star is moving away from Earth.
194. When electromagnetic radiation (e.g., light) is Doppler-shifted by motion of the source away from the detector, the measured
A) speed of the radiation is less than the emitted speed.
B) frequency is higher than the emitted frequency.
C) frequency of the radiation remains the same, but its wavelength is shortened, compared to the emitted radiation.
D) wavelength is longer than the emitted wavelength.
195. The wavelength 0 of light emitted by a moving object is detected as a different wavelength by a stationary observer. If v is the velocity of the object and c is the velocity of light, this Doppler shift can be described by the equation
A) – 0 = v – c.
B) /0 = v/c.
C) 0 = vc.
D) ( – 0)/0 = v/c.
196. A police radar device bounces radio waves of wavelength 3 mm from the front of a speeding car and measures the Doppler shift in wavelength of the reflected waves. What will be the wavelength shift if the car is moving at 60 mph (80 km/h or 22.2 m/s) (in a 30 mph zone)? Note that the shift is doubled because of the reflection.
A) 0.44 nm
B) 0.44 m
C) 4.4 m
D) 4.4 m
197. Hydrogen gas emits a strong spectral line of red light with a wavelength of 656.3 nm (the Balmer line). This emission line is seen in the spectrum of a distant quasar but at a wavelength of 721.9 nm. Applying Doppler’s relationship, how fast is this object moving with respect to Earth, in terms of the velocity of light, c?
A) 1/10 c
B) 1.1 c
C) 1/100 c
D) 10 c
198. An astronomer measures the spectrum of a star and finds a spectral line at 499 nm wavelength. In the laboratory, this spectral line occurs at 500 nm. According to the Doppler effect, this object is moving _____ Earth at _____the speed of light.
A) toward; 1/500
B) away from; 1/500
C) toward; 499/500
D) away from; 499/500
199. An astronomer observing the spectrum of the Sun on the solar equator finds that the Balmer H spectral line ( = 486 nm) is blueshifted by 0.0033 nm when measured at one edge of the Sun’s disk compared with the same line at the center of the Sun’s disk and is redshifted by the same amount on the equator at the other side of the Sun’s disk. If this Doppler shift is due to the Sun rotating (try drawing a diagram), then the rotational speed of the Sun at its equator is
A) 1 km/s.
B) 0.5 km/s.
C) 2 km/s.
D) 4 km/s.
200. A source emitting waves of constant wavelength approaches an observer, then passes the observer, and recedes into the distance—all at a constant speed. The wavelength of the waves the observer measures from this source
A) remains constant.
B) gradually becomes longer and longer as the source approaches the observer and then becomes even longer as the source recedes from the observer.
C) gradually becomes shorter and shorter as the source approaches the observer and then gradually becomes longer and longer as the source recedes from the observer.
D) is shorter (and constant) as the source approaches the observer and then suddenly becomes longer (and constant) as the source recedes from the observer.
201. When an object is moving toward an observer, the visible light it emits is Doppler-shifted toward the
A) ultraviolet.
B) infrared.
C) radio.
D) ultrasonic.
202. When an object is moving away from an observer, the visible light it emits is Doppler-shifted toward the
A) ultraviolet.
B) infrared.
C) radio.
D) ultrasonic.
203. Proper motion is the motion
A) of a star or other object across (at right angles to) the line of sight.
B) of a star or other object along the line of sight, toward or away from us.
C) allowed by the laws of physics.
D) of a star or other object in any direction through space.
204. An astronomer, examining two photographs of a small area of sky taken 20 years apart, notices that some of the stars have moved slightly across the sky, relative to most of the other stars in the photographs. This displacement of the stars across the sky is an example of
A) proper motion.
B) Doppler shift.
C) precession.
D) radial velocity.
205. The proper motion of a star or other object is measured by
A) measuring the intensity of the light in different regions of the blackbody curve.
B) observing the Doppler shift of spectral lines in the light from the object.
C) measuring the change in the angular diameter of the object.
D) watching the object move compared to the background stars.
206. The proper motions of stars are
A) easy to measure for most stars on photographs taken 6 months apart.
B) noticeable to the unaided eye as a gradual shift of the constellations westward over the course of a month or two.
C) easy to observe with the unaided eye over the course of an hour or two.
D) difficult to measure even on photographs taken several years apart for any but the nearest stars.
207. The angular motion of a star across the celestial sphere is a measure of its
A) radial velocity.
B) axial velocity.
C) total velocity.
D) proper motion.
208. The radial velocity of a star or other object is measured by
A) measuring the change in the angular diameter of the object.
B) watching the object move compared to the background stars.
C) measuring the intensity of the light in different regions of the blackbody curve.
D) observing the Doppler shift of spectral lines in the light from the object.
209. The star alpha Proxima Centauri, the nearest star beyond the Sun, is 22 km closer to the Sun every second. This motion of alpha Proxima Centauri toward the Sun is an example of
A) radial velocity.
B) precession.
C) elongation.
D) proper motion.
210. A star looks predominantly yellow to an observer who is at rest with respect to the star. To an observer moving away from the star at 1% of the speed of light, the star will look predominantly
A) red.
B) blue.
C) yellow, but each part of the spectrum will be shifted to slightly shorter wavelengths.
D) yellow, but each part of the spectrum will be shifted to slightly longer wavelengths.
211. The Kelvin scale measures
A) temperature in Fahrenheit-sized degrees above absolute zero.
B) temperature referenced to zero at the freezing point of water.
C) mass per unit volume, or density, with water having a value of 1.0.
D) temperature in Celsius-sized degrees above absolute zero.
212. What is the main reason that astronomers (and other scientists) almost always use the Kelvin (absolute) temperature scale rather than the Celsius or Fahrenheit scales?
A) The scale has a physically meaningful absolute zero of temperature.
B) The temperatures of freezing and boiling water are easier to remember.
C) Calculations are easier on the Kelvin scale.
D) The size of each degree (or unit) of temperature is more convenient.
213. A typical but very cool star might have a temperature of 3100°C. On the Kelvin scale, this is about
A) 3373 K.
B) 3068 K.
C) 3100 K.
D) 2827 K.
214. A scientist reports that his measurement of the temperature of the surface of a newly discovered planet is –20 K. What conclusion can be drawn from this report?
A) The scientist measured only the dark side of the planet, away from the Sun.
B) The planet has no atmosphere.
C) The planet is a very long way from the Sun.
D) The result is erroneous because absolute temperature cannot be negative.
215. The normal temperature of the melting point of water ice is
A) 293 K.
B) 273 K.
C) 0 K.
D) 100 K.
216. On the absolute Kelvin temperature scale, the temperature of freezing water is about
A) –273 K.
B) 273 K.
C) 373 K.
D) 0 K.
217. The temperature of boiling water at ordinary air pressure on the absolute Kelvin temperature scale is
A) 273 K.
B) 212 K.
C) 100 K.
D) 373 K.
218. The range of temperatures in the Kelvin (absolute) scale between the freezing point and boiling point of water is
A) 100 degrees.
B) 212 degrees.
C) 10 degrees.
D) 273 degrees.
219. A scientist measures the temperature change between freezing water and boiling water with a thermometer calibrated in the Kelvin or absolute scale. How many degrees Kelvin (K) will he measure?
A) 273
B) 100
C) 180
D) 373
220. The temperature at the top of the clouds on Jupiter is about 165 K. In degrees Celsius, this temperature is
A) 0°C.
B) –165°C.
C) –108°C.
D) 438°C.
221. The minimum temperature reached on the surface of Mars, –140°C, is represented on the absolute (Kelvin) temperature scale as
A) 133 K.
B) 153 K.
C) –133 K.
D) 140 K.
222. Which one of these temperatures is hottest?
A) 100 K
B) 100°C
C) 100°F
D) They are all the same.
223. An astronomer begins with an object at a certain temperature, and increases its temperature by an amount T. For which one of these values of T will the final temperature of the object be LOWEST?
A) T = 10 Kelvins
B) T = 10 degrees Celsius
C) T = 10 degrees Fahrenheit
D) All of the answers give the same final temperature.