Assignment 6 Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. Which part of the Sun has the greatest density? a. the photosphere b. the core c. the convection region d. the corona e. you can't fool me; since the Sun is made of gas, all its parts have the same density 2. You are out on the beach, enjoying the warm sunshine with friends. As you glance (briefly we hope) up at the Sun, the part of the Sun that you can see directly is called its: a. corona b. photosphere c. chromosphere d. core e. heliopause 3. How do astronomers know what the outer layers of the Sun are made of? a. we send graduate students there to get samples b. spacecraft with good shielding have approached the Sun and obtained samples c. the surface layers of Mercury have been laid down by the Sun and are thus made of the same material as the Sun d. the Sun's wind gives us an accurate measure of all the different elements in the Sun e. we take an absorption line spectrum of the Sun, and the absorption lines tell us what elements are present in the outer layers 4. The most common element in the Sun is a. helium b. iron c. hydrogen d. water e. nitrogen 5. The hotter region directly above the Sun's visible surface is called the a. chromosphere b. photosphere c. corona d. ionization region e. convection zone
6. As you go upwards from the Sun's photosphere, a. the temperature decreases b. the density (number of atoms in a unit volume) decreases c. the layers get easier to see with the unaided eye d. the kinds of atoms present change drastically e. only red light can emerge 7. Which part of the Sun's atmosphere is the hottest? a. chromosphere b. transition region c. corona d. just above the photosphere e. you can't fool me, all these regions are at roughly the same temperature 8. Which part of the Sun's atmosphere has the lowest density (number of atoms per unit volume)? a. corona b. transition region c. chromosphere d. just above the photosphere e. you can't fool me, all these regions are at roughly the same density 9. As astronomers have learned more about the structure of the Sun, they have found that it a. has a small solid core inside b. is made entirely of liquid and (on the outside) hot gas c. is solid throughout, but with a large very hot atmosphere d. is made entirely of hot gas e. is made of billions of individual pieces of hot rock, all orbiting around each other in a whirling arrangement 10. Solar wind particles can be captured by the Earth's magnetosphere. When these particles spiral down along the magnetic field into the atmosphere, they are responsible for: a. aurorae (northern and southern lights) b. tropical storms (regions of rapidly rotating air) c. the greenhouse effect d. the reddish color we see during sunsets e. the poor quality of television programming in the world's northern hemisphere 11. What mechanisms do astronomers believe is responsible for making the Sun's outer atmosphere so much hotter than its photosphere? a. stirring by comets, meteors, and other pieces of solid material being pulled in by the Sun's strong gravity b. light reflected back from the terrestrial planets c. the Sun's magnetic field interacting with the charged particles that make up the atmosphere d. the ionization of a new element called coronium e. astronomers really don't have even a theory about what heats the Sun's outermost layers
12. The granulation pattern that astronomers have observed on the surface of the Sun tells us that: a. the Sun is a lot cooler on the inside than on the outside b. the Sun's surface is made of a thin solid that cracks easily c. hot material must be rising from the Sun's hotter interior d. the solar wind must consist of very small (low mass) particles e. the Sun accumulates a lot of dirt and dust because of its large gravity 13. Sunspots are darker than the regions of the Sun around them because a. they consist of different elements than the rest of the Sun b. they are located in the corona and not on the photosphere c. they move much faster around the Sun than other material and thus heat up d. they are the shadows of the planets and asteroids seen on the bright surface of the Sun e. they are cooler than the material around them (although still very hot compared to Earth temperatures) 14. Astronomers now realize that active regions on the Sun are connected with a. the dark regions between the bright granulation cells on the photosphere b. loops of magnetic field emerging from the surface of the Sun c. the absence of sunspots during a solar minimum d. great tropical storm systems in the Earth's atmosphere e. changes in the gravitational pull of the Sun over different parts of its photosphere 15. Astronomers have concluded that the Sun's activity varies in an 11 year cycle. Which of the following statements about this cycle is TRUE: a. Every 11 years sunspots completely cover the Sun, making its surface much darker b. The number of sunspots gets larger and smaller over the course of 11 years c. When sunspots are at a minimum, we get the largest number of flares and prominences d. The Sun's activity cycle shows absolutely no connection to its magnetic field e. The Sun's activity cycle is directly connected to the number of earthquakes at the continental plate boundaries on Earth 16. Which of the following is not part of some active regions on the Sun? a. sunspots b. flares c. plages d. prominences e. granulation 17. How do astronomers know how strong the magnetic field of the Sun is? a. they measure the magnetic field of the Earth, which is a direct result of the magnetic field of the Sun b. they measure the Sun's rotation using the Doppler effect c. they count the number of days in the year that we get an aurora in the upper atmosphere d. the measure the Zeeman effect (the splitting of spectral lines) e. the diameter of a star is directly related to the size of its magnetic field
18. Coronal Mass Ejections from the Sun have many serious effects on or near the Earth. Which of the following is NOT one of these effects? a. disrupting the electronics of satellites b. heating the ionosphere and thus expanding the extent of our planet's atmosphere c. causing power surges and power outages in parts of the Earth near the poles d. causing huge cyclones around the equator of the Earth e. exposing astronauts and airplane passengers to increased amounts of radiation 19. Today we realize that the source of energy for the Sun is a process called a. nuclear fusion b. Kelvin Helmholtz contraction c. mechanical to thermal energy conversion d. radioactivity e. dilithium crystal moderation 20. According to the formula E=mc 2, a. mass has to travel at the speed of light before it can produce any energy b. energy can travel much faster than light (in fact its speed can be the speed of light squared) c. a little bit of mass can be converted into a substantial amount of energy d. when two masses collide, we always get a lot of light e. Einstein was a male chauvinist twice over 21. In the formula E=mc 2, the letter c stands for a. the speed of sound b. the speed of an electron around the nucleus c. the amount of energy contained in one hydrogen nucleus d. the energy of a neutrino emerging from the Sun e. the speed of light 22. The antimatter version of an electron is called a a. proton b. neutrino c. antitron d. positron e. gammatron 23. In the Sun, when a positron and an electron collide, they will produce: a. a deuteron b. a neutron c. hydrogen d. a neutron e. energy in the form of a gamma ray
24. Which of the following statements about antimatter is true? a. antimatter is only a theory, we have no evidence that it exists b. antimatter only exists in Earth laboratories; it cannot be made in stars c. antimatter cannot be made in laboratories; we have tried but it just can't be done d. when equal amounts of matter and antimatter meet, they become pure energy e. our telescopes clearly see many antimatter stars in the Milky Way galaxy 25. As originally suggested by Wolfgang Pauli, neutrinos have the following property: a. they travel at the speed of light b. they have no mass c. they interact very weakly with ordinary matter d. they can be considered little packets of energy e. all of the above 26. A college friend of yours who has been postponing taking any science courses hears you talking about the generation of nuclear energy in the Sun and makes the following observation: "The whole idea of the atomic nucleus is pretty ridiculous. If an oxygen nucleus consists of eight protons and eight neutrons, the charge on the nucleus is positive. Since even I learned in high school that like charges repel, such a nucleus would find itself repulsive and quickly fall apart." How would you answer his argument. a. gravity is much stronger than electric repulsion and holds every nucleus together b. the neutrons in the nucleus are negative, so they cancel the positive charge on the protons c. the nuclear force, which is attractive and stronger than electricity, holds the nucleus together d. the electrons outside the nucleus repel the protons and keep them inside the nucleus e. there is no answer; scientists do not have a clue about how the nucleus manages to keep itself together 27. Which of the following particles has the lowest mass? a. a neutrino b. a proton c. a neutron d. an electron e. the nucleus of a hydrogen atom 28. The strongest force we know is a. gravity, which holds the Earth and the Sun together b. electricity, which pulls unlike charges together c. the nuclear force which holds nuclei together d. the attraction of Bayonne, New Jersey, for tourists e. none of the above
29. When two light elements undergo nuclear fusion, a. the total mass involved increases b. the like charges in the nuclei attract, pulling the nuclei together faster and faster c. some of the energy in their mass is released d. only one survives; the other turns into a release of pure energy e. the result is always to make nuclei of iron 30. When a large nucleus breaks apart (or is broken apart) into two smaller pieces, this is called a. nuclear fusion b. nuclear binding c. the p p chain d. equilibrium breaking e. nuclear fission 31. Where in the Sun does fusion of hydrogen occur? a. only in the core b. only near the photosphere (its visible surface layer) c. pretty much throughout the Sun d. only in the layer where there is a lot of convection going on e. nowhere 32. If it takes an average of 14 billion years before any proton inside the Sun will undergo fusion, and the Sun is only about 5 billion years old, why do astronomers believe that fusion is going on there now? a. fusion begins with particles even lighter than protons, which fuse more easily b. there are an enormous number of protons inside the Sun, so some will fuse much sooner than the average c. fusion takes place in the hot atmosphere of the Sun (where it can happen faster), not inside (where it is slow) d. fusion inside the Sun involves carbon, not protons; carbon fuses much more quickly e. there is no fusion going on inside the Sun, and the fact cited in the question is one of the reasons why 33. The process of fusion that keeps our Sun shining begins with which building blocks? a. two electrons b. two deuterons c. two protons d. two Einsteinium nuclei e. two neutrinos 34. Which of the following is NOT a product of the first step in the p p chain of nuclear fusion? a. a form of hydrogen b. a positron c. a neutrino d. a deuteron e. a form of helium
35. At the end of the p p chain of nuclear fusion in the Sun, hydrogen nuclei have been converted into: a. carbon nuclei b. heavy hydrogen nuclei c. antimatter and nothing else d. a helium nucleus e. a lithium nucleus 36. Who pays the bill for the energy generated by nuclear fusion in the Sun? In other words, where does the energy pouring out of the Sun come from ultimately? a. the Sun is spinning more slowly as time goes on; rotation energy is lost b. heavy nuclei are breaking apart into lighter nuclei c. a little bit of mass is lost in each reaction and is turned into energy (the Sun is losing mass) d. material is falling into the Sun and being vaporized to produce energy e. American taxpayers pay this bill, as they do so many others! 37. What happens to the positron created during the p p chain of nuclear reactions inside the Sun? a. it merges with a proton to become a deuterium (heavy hydrogen) nucleus b. it quickly collides with an electron and turns into gamma ray energy c. it ultimately forms an anti helium nucleus d. it turns quickly into a neutrino, which can escape from the Sun e. it just sits there at the core of the Sun for billions of years, unable to interact 38. The Sun is an enormous ball of gas. Left to itself, a ball of so many atoms should collapse under its own tremendous gravity. Why is our Sun not collapsing? a. the gravity of the planets around the Sun pulls its material outward, preventing collapse b. the pressure of the corona keeps the Sun's main body of gases confined to a small volume c. nuclear fusion in the core keeps the temperature and the pressure inside the Sun at a high enough level so that gravity is balanced d. neutrinos from the core exert an enormous pressure on the layers of the Sun as they travel outward, and keep our star from collapsing e. you can't fool me, the Sun is shrinking all the time, it just happens very slowly 39. When great currents of hot material rise inside the Sun (and cooler material sinks downward), energy is being transferred by a process known as: a. convection b. radiation c. conduction d. equilibrium e. politics
40. Which of the following, produced at the core of the Sun, will take the shortest time to emerge from the Sun's photosphere (surface)? a. a photon (wave) of gamma rays b. a positron c. a neutrino d. a deuteron e. an x ray produced after radiation has interacted with matter in the core
Assignment 6 Answer Section MULTIPLE CHOICE 1. ANS: B 3. ANS: E 5. ANS: A 7. ANS: C 9. ANS: D 11. ANS: C 13. ANS: E 15. ANS: B 17. ANS: D 19. ANS: A 21. ANS: E 23. ANS: E 25. ANS: E 27. ANS: A 29. ANS: C 31. ANS: A 33. ANS: C 35. ANS: D 37. ANS: B 39. ANS: A