Chapter 14

Basic Skills/Definitions Quiz
Part A
According to modern science, approximately how old is the Sun?
Hint A.1
Study Section 14.1
ANSWER:

10,000 years 400 million years. 4.6 billion years 25 million years
Part B
The Sun will exhaust its nuclear fuel in about ______.
Hint B.1
Study Section 14.1
ANSWER:

5000 AD. 50 billion years. 5 billion years. 5 million years.
Part C
Which of the following correctly describes how the process of gravitational contraction can make a star hot?
Hint C.1
Study Section 14.1
ANSWER:

Heat is generated when gravity contracts, because gravity is an inverse square law force. Gravitational contraction involves the generation of heat by chemical reactions, much like the burning of coal. Gravitational contraction involves nuclear fusion, which generates a lot of heat. When a star contracts in size, gravitational potential energy is converted to thermal energy.
Part D
What two physical processes balance each other to create the condition known as gravitational equilibrium in stars?
Hint D.1
Study Section 14.1.
ANSWER:

The strong force and the weak force. The gravitational force and surface tension. The gravitational force and outward pressure. The strong force and the electromagnetic force.
Part E
The source of energy that keeps the Sun shining today is ______.
Hint E.1
Study Section 14.1.
ANSWER:

chemical reactions. gravitational contraction. nuclear fission. nuclear fusion.
Part F
What is the Sun made of (by mass)?
Hint F.1
Study Section 14.2
ANSWER:

90% dark matter, 10% ordinary matter. 70% hydrogen, 28% helium, 2% other elements 100% hydrogen and helium 50% hydrogen, 25% helium, 25% other elements
Part G
From center outward, which of the following lists the "layers" of the Sun in the correct order?
Hint G.1
Study Section 14.1
ANSWER:

core, radiation zone, convection zone, photosphere, chromosphere, corona core, convection zone, radiation zone, corona, chromosphere, photosphere core, radiation zone, convection zone, corona, chromosphere, photosphere core, corona, radiation zone, convection zone, photosphere, chromosphere
Part H
What are the appropriate units for the Sun's luminosity?
Hint H.1
Study Section 14.1
ANSWER:

Newtons Watts Joules Kilograms
Part I
The Sun's surface, as we see it with our eyes, is called the
Hint I.1
Study Section 14.1.
ANSWER:

corona photosphere core chromosphere
Part J
The Sun's average surface (photosphere) temperature is about ______.
Hint J.1
Study Section 14.2
ANSWER:

37,000 K. 5,800 K. 1,000,000 K 1,000 K.
Part K
What is the solar wind?
Hint K.1
Study Section 14.1
ANSWER:

It is the wind that causes huge arcs of gas to rise above the Sun's surface, sometimes staying aloft for weeks. It is the uppermost layer of the Sun, lying just above the corona. It is the name we give to the gas (or plasma) particles flowing outward from the surface of the Sun into the solar system. It is the strong winds that blow across the surface of the Sun, causing sunspots to move around randomly.
Part L
The fundamental nuclear reaction occurring in the core of the Sun is:
Hint L.1
Study Section 14.2
ANSWER:

Nuclear fission Nuclear fusion of helium to carbon. Radioactive decay Nuclear fusion of hydrogen to helium.
Part M
What is the proton-proton chain?
Hint M.1
Study Section 14.2
ANSWER:

It describes the linkage between protons into long chains that occurs when temperatures are very high. It is another name for the force that holds protons together in atomic nuclei. It is an alternative way of generating energy by nuclear fusion besides fusing hydrogen into helium. It is the specific set of nuclear reactions through which the Sun fuses hydrogen into helium.
Part N
The overall result of the proton-proton chain is:
Hint N.1
Study Section 14.3
ANSWER:

Individual protons are joined into long chains of protons. 4 H becomes 1 He + energy. p + p becomes 2H + energy 6 H becomes 1 He + energy.
Part O
Why are neutrinos so difficult to detect?
Hint O.1
Study Section 14.2.
ANSWER:

They have no mass. No one knows: this is the essence of the "solar neutrino problem." They are extremely rare. They have a tendency to pass through just about any material without any interactions.
Part P
To estimate the central temperature of the Sun, scientists ______.
Hint P.1
Study Section 14.2
ANSWER:

monitor changes in Earth's atmosphere. send probes to measure the temperature. create a version of the Sun in a laboratory. use computer models to predict interior conditions.
Part Q
Which of the following best describes the current status of our understanding of the solar neutrino problem?
Hint Q.1
Study Section 14.2
ANSWER:

Experimental evidence suggests that solar neutrinos can change from electron neutrinos to other types of neutrinos during their journey to Earth. The solar neutrino problem appears to be solved. The solar neutrino problem remains as perplexing as ever, and indeed makes everything we think we know about stars suspect. We have learned that the Sun's interior undergoes fusion at a far lower rate than we had expected, and that is why we had observed fewer neutrinos than expected. Recent evidence suggests that the solar neutrino problem really was not a problem at all, and only seemed to be a problem because experimental data were being misinterpreted.
Part R
The light radiated from the Sun's surface reaches Earth in about 8 minutes, but the energy of that light was released by fusion in the solar core ______.
Hint R.1
Study Section 14.2
ANSWER:

a few hundred thousand years ago. about 9 minutes ago about three days ago. about a hundred years ago. about a thousand years ago.
Part S
What happens to energy in the Sun's convection zone?
Hint S.1
Study Section 14.2
ANSWER:

Energy is produced in the convection zone by thermal radiation. Energy is produced in the convection zone by nuclear fusion. Energy is transported outward by the rising of hot plasma and sinking of cooler plasma. Energy slowly leaks outward through the radiative diffusion of photons that repeatedly bounce off ions and electrons.
Part T
What do sunspots, solar prominences, and solar flares all have in common?
Hint T.1
Study Sections 14.3
ANSWER:

They all occur only in the Sun's photosphere. The are all strongly influenced by magnetic fields on the Sun. They are all shaped by the solar wind. They all have about the same temperature.
Part U
Which of the following is NOT a characteristic of the 11-year sunspot cycle?
Hint U.1
Study Section 14.3
ANSWER:

The sunspot cycle is very steady, so that each 11-year cycle is nearly identical to every other 11-year cycle. The likelihood of seeing solar prominences or solar flares is higher when sunspots are more common and lower when they are less common. The Sun's entire magnetic field flip-flops at the end of each cycle (at solar minimum). The number of sunspots on the Sun at any one time gradually rises and falls, with an average of 11 years between the times when sunspots are most numerous.
Part V
How is the sunspot cycle directly relevant to us here on Earth?
Hint V.1
Study Section 14.3
ANSWER:

The brightening and darkening of the Sun that occurs during the sunspot cycle affects plant photosynthesis here on Earth. The sunspot cycle strongly influences Earth's weather. The Sun's magnetic field, which plays a major role in the sunspot cycle, affects compass needles that we use on Earth. Solar flares and other activity associated with the sunspot cycle can disrupt radio communications and knock out sensitive electronic equipment.