Our Star The Sun Verified Test Bank Ch.11 Third Edition - Understanding Our Universe 3e Complete Test Bank by Stacy Palen. DOCX document preview.
Chapter 11: Our Star: The Sun
LEARNING OBJECTIVES
11.1 The Structure of the Sun Is a Matter of Balance
11.1a Describe hydrostatic equilibrium.
11.1b Relate how a change in internal characteristics of a star (for example, core temperature, energy generation) will change its surface characteristics (for example, surface temperature, luminosity, size).
11.1c Explain why nuclear fusion is able to generate energy.
11.1d Describe the conditions needed for nuclear fusion to occur.
11.1e Describe the conditions in the sun as a function of its radius.
11.1f Describe the steps by which hydrogen is fused into helium in the Sun in the proton-proton chain.
11.1g Discuss how neutrino detection was used to test our theory of nuclear fusion in the Sun and how that led to a better understanding of neutrinos themselves.
11.2 Energy in the Sun’s Core Moves through Radiation and Convection
11.2a Compare and contrast the conditions under which energy in the Sun is transported by radiation and by convection.
11.2b Explain how helioseismology has been used to probe the structure of the Sun.
11.3 The Atmosphere of the Sun
11.3a Describe the effect of limb darkening.
11.3b Determine why sunlight has an absorption spectrum even though we treat it as a blackbody.
11.4 The Atmosphere of the Sun Is Very Active
11.4a Describe how magnetic effects in the Sun create its solar activity.
11.4b Characterize the extent to which solar activity creates measurable effects on Earth and beyond.
Working It Out 11.1
Working It Out 11.1a Calculate the energy given off during nuclear fusion.
Working It Out 11.1b Relate the mass, luminosity, fuel consumption, and lifetime of a star powered by nuclear fusion.
Working It Out 11.2
Working It Out 11.2a Use the Stefan-Boltzmann law to compare the temperature and flux of a star’s surface to its sunspots.
Chapter 11: Our Star: The Sun
MULTIPLE CHOICE
1. The Sun has a mass of
a. 2 
1030 kilograms (kg). c. 2 1020 kg.
b. 2 1010 kg. d. 2 1040 kg.
2. The majority of the Sun’s energy comes from
a. gravitational contraction. c. hydrogen fusion.
b. its rapid rotation. d. helium burning.
3. The energy that powers the Sun is generated
a. only on its surface.
b. only in its core.
c. both in its core and on its surface.
d. in its core, on the surface, and in the solar wind.
4. Given the following plot of density vs radius for the sun, what can you say about the location of the bulk of its mass?
a. Almost all of the mass is within 0.2 solar radii.
b. Almost all of the mass is within 0.5 solar radii.
c. Almost all of the mass is within 0.75 solar radii.
d. All the mass is evenly distributed throughout the Sun.
5. When two atomic nuclei come together to form a new species of atom, it is called
a. nuclear fission. c. nuclear splitting.
b. nuclear fusion. d. nuclear recombination.
6. When two atomic nuclei come together to form a new species of atom, what force must be overcome?
a. strong nuclear force c. electric force
b. gravity d. weak force
7. When two atomic nuclei come together to form a new species of atom, what force engages to keep them together?
a. strong nuclear force c. electric force
b. gravity d. weak force
8. What force only acts at short distances of the order 10–15 meters?
a. strong nuclear force c. electric force
b. gravity d. They all work at infinite distances.
9. Density, temperature, and pressure __________ as you move inward in the interior of the Sun.
a. increase c. stay the same
b. decrease d. There is not enough information provided.
10. Detection of solar neutrinos confirms that
a. the Sun’s core is powered by proton-proton fusion.
b. transport by radiation occurs throughout much of the solar interior.
c. magnetic fields are responsible for surface activity on the Sun.
d. convection churns the base of the solar atmosphere.
11. If neutrinos oscillated between four different types of neutrino during their transit from the Sun to Earth, then how many neutrinos would we have detected compared with what was emitted by the Sun?
a. one-third as many c. one-fifth as many
b. one-fourth as many d. We would detect no neutrinos.
12. The bulk of the Sun’s energy generation is contained within a region of
a. 0.2 solar radii. c. 0.75 solar radii.
b. 0.5 solar radii. d. 1.0 solar radii.
13. Examine the following graph. What can be said about where the energy is generated in the sun?
a. All energy comes from the inner 30%.
b. All energy comes from the inner 50%.
c. All energy comes from the inner 75%.
d. It is evenly generated throughout the Sun.
14. In the proton-proton chain, the net reaction is that four hydrogen nuclei are converted to one helium nucleus and __________ are released.
a. visible wavelength photons c. ultraviolet photons and neutrinos
b. gamma-ray photons and neutrinos d. X-ray photons, electrons, and neutrinos
15. Which by-product of the proton-proton chain freely escapes the Sun’s interior?
a. visible photons c. neutrinos
b. gamma-ray photons d. positrons
16. What are positrons?
a. visible photons c. neutrinos
b. gamma-ray photons d. positively charged electrons
17. Hydrostatic equilibrium is a balance between
a. heat and rotation.
b. core temperature and surface temperature.
c. forces due to radiation pressure and gravity.
d. radiation and heat.
18. Why is hydrogen burning the main energy source for main-sequence stars?
a. Hydrogen is the most common element in stars.
b. Hydrogen nuclei have the smallest positive charge.
c. Hydrogen burning is the most efficient of all fusion or fission reactions.
d. All are valid reasons.
19. The solar neutrino problem was solved by
a. adjusting the rates of hydrogen burning in solar models.
b. improving detector efficiencies so more neutrinos were observed.
c. postulating that neutrinos had mass and oscillated between three different types.
d. lowering the percentage of helium in models of solar composition.
20. Balance of energy in the solar interior means that
a. the energy production rate in the core equals the rate of radiation escaping the Sun’s surface.
b. the source of energy in the core is stable and will sustain the Sun for billions of years.
c. the outer layers of the Sun absorb and reemit the radiation from the core at increasingly longer wavelengths.
d. radiation pressure balances the weight of the overlying solar layers.
21. If the Sun converts 5 1011 kg of H to He per second, and 10 percent of the Sun’s total mass is available for nuclear burning, how long might we expect the Sun to live?
a. 104 years c. 1010 years
b. 108 years d. 1014 years
22. If the Sun converts 5 1011 kg of H to He per second, and the mass of a single hydrogen nucleus is 1.7 1027 kg, how many net proton-proton reactions go on per second in the Sun? What is the luminosity produced if the mass difference between a single helium nucleus and four hydrogen nuclei is 4 1029 kg? Note that 1 watt (W) 
1 m2 kg/s3.
a. 7 1037 reactions per second; 3 1026 W
b. 3 1038 reactions per second; 1027 W
c. 3 1038 reactions per second; 4 1026 W
d. 7 1037 reactions per second; 5 1025 W
23. Approximately how long does it take the energy of the photons released in nuclear reactions in the core of the Sun to exit the photosphere?
a. 8 minutes c. 1,000 years
b. 16 hours d. 100,000 years
24. Examine the following figure. By studying how the surface of the Sun vibrates like a struck bell, we can determine its
a. age. c. total mass.
b. interior density. d. size.
25. Approximately what is the temperature at the center of the Sun?
a. 1500 Kelvin (K) c. 15 million K
b. 15,000 K d. 15 billion K
26. Which of the following layers of the Sun makes up the majority of its interior?
a. the core c. the convective zone
b. the radiative zone d. the photosphere
27. What is the order of how energy is transported from the Sun’s core to its surface?
a. radiation, convection, radiation c. convection, radiation, radiation
b. radiation, conduction, radiation d. conduction, radiation, radiation
28. Examine the following figure. The interior zones of the Sun are distinguished by
a. jumps in density between zones. c. their modes of energy transport.
b. their temperature profiles. d. All choices are valid.
29. We can determine how the density changes with radius in the Sun using
a. radar observations. c. high-energy (gamma ray) observations.
b. neutrino detections. d. helioseismology.
30. Light from the photosphere of the Sun reaches Earth approximately __________ times faster than photons released by fusion in the Sun’s core.
a. 1,000 c. 1 million
b. 600,000 d. 6 billion
31. Examine the following figure. The corona of the Sun has a temperature of approximately 1 million K. At what wavelength and in what part of the electromagnetic spectrum does its radiation peak?
a. 5.5 107 meter, visible c. 4 107 meter, ultraviolet
b. 2 105 meter, infrared d. 3 109 meter, X-rays
32. We know the corona of the Sun is very hot because
a. we observe it emitting large amounts of radio emission.
b. the chromosphere and the photosphere are so hot.
c. we observe it emitting X-rays that ionize atoms there.
d. All choices are valid.
33. The solar spectrum (see the following image) is an example of a(n) __________ spectrum.
a. absorption c. continuum
b. emission d. blackbody
34. What is the best wavelength to observe a solar prominence or flare as seen on the edge of the Sun here?
a. 550 nanometers (nm), green visible light c. 16 millimeters (mm), an ultraviolet emission line
b. 656 nm, a red hydrogen emission line d. 21 centimeters (cm), microwave emission
35. The chromosphere appears red because
a. it is hotter than the photosphere.
b. as the Sun rotates, the chromosphere appears to move away from us radially.
c. it has a higher concentration of heavy metals.
d. its spectrum is dominated by H emission.
36. Roughly how thick is the photosphere?
a. 100 kilometers (km) c. 500 km
b. 200 km d. 1,000 km
37. The bulk of the light we see from the Sun emanates from the
a. core. c. chromosphere.
b. photosphere. d. corona.
38. The surface of the Sun appears sharp because the photosphere is
a. cooler than the layers below it.
b. thin compared with the other layers in the Sun.
c. much less dense than the convection zone.
d. transparent to radiation.
39. Which of the following are manifestations of solar magnetic activity?
a. sunspots c. flares
b. prominences d. All choices are valid.
40. How far out have the magnetic effects of the Sun been directly measured?
a. out to Earth c. out to Pluto
b. out to Jupiter d. near the boundaries of interstellar space
41. Sunspots appear dark because they
a. have lower densities.
b. have lower rotation rates.
c. have lower temperatures.
d. are storm systems like those on the giant planets.
42. The Sun’s magnetic field reverses polarity every
a. 27 days. c. 11 years.
b. 12 months. d. 22 years.
43. Which of the following is a result of an increase in solar activity?
a. The height of orbiting satellites decreases.
b. Airplanes have trouble navigating.
c. Stronger auroras are seen.
d. All choices are valid.
44. The variations in the Sun’s luminosity by solar activity accounts for a change in Earth’s average temperature by 0.1 K, which is
a. much less than what is attributed to greenhouse gases in Earth’s atmosphere.
b. equal to the current trends in Earth’s global warming.
c. much more than what is attributed to greenhouse gases in Earth’s atmosphere.
d. This is a trick question; there is no global warming.
45. The Maunder Minimum was a 60-year period when
a. debris thrown up in a comet collision blanketed out the Sun.
b. almost no sunspots occurred on the Sun.
c. the Voyager 2 spacecraft traversed the heliopause.
d. no dust storms occurred on Mars.
46. If a coronal mass ejection occurs on the Sun that expels material directly toward Earth at a speed of 1,500 kilometers per second (km/s), how long will it take these charged particles to reach Earth?
a. 0.7 day c. 1.8 days
b. 1.2 days d. 2.1 days
47. Early observations of sunspots led to the discovery of the Sun’s
a. coronal holes. c. differential rotation.
b. coronal mass ejections. d. All choices are valid.
48. When solar activity is very high, Earth’s atmosphere will
a. expand. c. remain approximately the same.
b. contract. d. repel charged particles.
49. Examine the following figure. In a sunspot, the __________ is cooler than the __________.
a. umbra; penumbra c. penumbra; umbra
b. limb; center d. lighter; darker
50. If a sunspot appears one-fourth as bright as the surrounding photosphere, and the average temperature of the photosphere is 5800 K, what is the temperature of the gas in this sunspot?
a. 4100 K c. 5200 K
b. 4400 K d. 5500 K
1. Explain why hydrostatic equilibrium results in the center of the Sun having the highest pressure and temperature.
2. Why is hydrogen burning the main energy source for main-sequence stars? Give at least two reasons.
3. Examine the following figure. Show where in the Sun nuclear fusion occurs, and explain why fusion occurs there.
4. In the proton-proton chain, the net reaction is that four protons are converted into one helium nucleus. What other by-products are released in this reaction, and why?
5. Explain why the solution to the solar neutrino problem is an excellent example of how observations drive the evolution of science.
6. Describe the steps by which hydrogen is fused into helium in the Sun in the proton-proton chain.
7. Show that a star with the same mass, composition, radius, and luminosity as the Sun, but with a higher temperature (that is, a “too-hot” Sun), leads to a contradiction.
8. Through hydrogen fusion, the Sun loses approximately 4 million tons of mass each second. If it burns hydrogen at this rate for 10 billion years, what percentage of its original mass will it lose in all? (Note: The mass of the Sun is 1.99 1030 kg, and 1 ton 1,000 kg.)
9. Calculate the amount of energy released by converting four hydrogen atoms into one helium atom. The mass of a hydrogen atom is 1.67 1024 gram (g); the mass of a helium atom is 6.65 10–24 g. The speed of light is 3 108 meters per second (m/s).
10. In the following figure, label the regions of the Sun.
11. What are the three ways in which energy could be transported within a star (or to your fingers)? Explain your answer.
12. Examine the following figure. Explain why it takes so long for gamma-ray energy to find its way to the outer layers of the Sun.
13. Label the zones and regions (A, B, C, and D) in the following figure.
14. What is “limb darkening”? Explain why limb darkening occurs in the Sun.
15. Explain why magnetic fields trap coronal gas over much of the solar surface but allow it to escape in coronal holes.
16. How do periods of strong solar activity affect near-Earth orbiting spacecraft?
17. If a coronal mass ejection occurred on the Sun and ejected particles toward Earth that traveled at the speed of 1,000 km/s, how long would it take them to reach Earth?
18. When, during its 11-year cycle, is the Sun most luminous? What might this have to do with the Maunder Minimum?
19. Explain why Voyager I may not have reached interstellar space.
20. If a sunspot is one third as bright as the surrounding photosphere of the Sun, what is the approximate temperature of the gas in the sunspot if the photosphere’s average temperature is 5800 K?