Astronomy Chapter 14 Test Questions – Flashcards
Unlock all answers in this set
Unlock answersquestion
In the late 1800s, Kelvin and Helmholtz suggested that the Sun stayed hot thanks togravitationalcontraction. What was the major drawback of this idea?
answer
D.)It predicted that the Sun could last only about 25 million years, which is far less than the ageof Earth.
question
When is/was gravitational contraction an important energy-generation mechanism for the Sun?
answer
C)when the Sun was being formed from a collapsing cloud of gas
question
What do we mean when we say that the Sun is ingravitational equilibrium?
answer
D)There is a balance within the Sun between the outward push of pressure and the inward pullof gravity.
question
What two forces are balanced in what we callgravitational equilibrium?
answer
B)outward pressure and gravity
question
What is the Sun made of?
answer
B)70 percent hydrogen, 28 percent helium, 2 percent other elements
question
The phase of matter in the Sun is
answer
D)plasma.
question
What are the appropriate units for the Sun'sluminosity?
answer
B)watts
question
What is the average temperature of thesurface of the Sun?
answer
D)6,000 K
question
Which is closest to the temperature of thecore of the Sun?
answer
D)10 million K
question
From the center outward, which of the following lists the "layers" of the Sun in the correct order?
answer
D)core, radiation zone, convection zone, photosphere, chromosphere, corona
question
Which layer of the Sun do we normally see?
answer
C)photosphere
question
The core of the Sun is
answer
D)hotter and denser than the surface
question
Based on its surface temperature of 5,800 K, what color are most of the photons that leave the Sun'ssurface?
answer
E)green
question
Why do sunspots appear dark in pictures of the Sun?
answer
D)They actually are fairly bright but appear dark against the even brighter background of thesurrounding Sun.
question
Sunspots are cooler than the surrounding solar surface because
answer
D)strong magnetic fields slow convection and prevent hot plasma from entering the region.
question
How does the Sun generate energy today?
answer
E)nuclear fusion
question
How do human-built nuclear power plants on Earth generate energy?
answer
D)nuclear fission
question
Hydrogen fusion in the Sun requires a temperature (in Kelvin) of
answer
C)millions of degrees.
question
19)At the center of the Sun, fusion converts hydrogen into
answer
A)helium, energy, and neutrinos.
question
How much mass does the Sun lose through nuclear fusion per second?
answer
A)4 million tons
question
Suppose you put two protons near each other. Because of the electromagnetic force, the twoprotons will
answer
E.)repel each other.
question
Which is the strongest of the fundamental forces in the universe?
answer
B)strong force
question
The first step in the proton-proton chain produces an antielectron, orpositron. What happens to thepositron?
answer
C)It is rapidly converted to energy when it meets an ordinary electron, resulting inmatter-antimatter annihilation.
question
The overall fusion reaction by which the Sun currently produces energy is
answer
B.) 4 H 1 He+ energy.
question
Why must the Sun's rate of fusion gradually rise over billions of years?
answer
D)Fusion reactions decrease the overall number of particles in the core, causing the core toshrink, converting gravitational potential energy into thermal energy, and increasing the rateof fusion.
question
Suppose that, for some unknown reason, the core of the Sun suddenly became hotter. Which of thefollowing best describes what would happen?
answer
B.)Higher temperature would cause the rate of nuclear fusion to rise, which would increase theinternal pressure, causing the core to expand and cool until the fusion rate returned to normal.
question
27)How do we know what goes on under the surface of the Sun?
answer
E)both B and D
question
Studies of sunquakes, orhelioseismology, have revealed that
answer
E)our mathematical models of the solar interior are fairly accurate.
question
Which statement best describes thesolar neutrino problem?
answer
B)Solar neutrinos have been detected, but in fewer numbers than predicted by theoreticalmodels.
question
Why are neutrinos so difficult to detect?
answer
A)because they rarely interact with matter
question
Which of the following statements about neutrinos isnot true?
answer
E)The mass of a neutrino is 30 percent of the mass of an electron.
question
What is a possible solution to thesolar neutrino problem?
answer
B)The electron neutrinos created in the Sun change into another type of neutrino that we do notdetect.
question
The light radiated from the Sun's surface reaches Earth in about 8 minutes, but the energy of thatlight was released by fusion in the solar core about
answer
A)a million years ago.
question
What happens to energy in theconvection zone of the Sun?
answer
A)Energy is transported outward by the rising of hot plasma and the sinking of cooler plasma.
question
Most of the energy produced in the Sun is released in the form of visible light from thephotosphere. However, some energy is released from the upper layers of the solar atmosphere.Which of the following best describes where other forms of light are released?
answer
B)The chromosphere is the source of ultraviolet light, and the corona is the source of X rays.
question
What is granulation in the Sun?
answer
E) the bubbling pattern on the photosphere produced by the underlying convection
question
What arecoronal holes?
answer
A) areas of the corona where magnetic field lines project into space, allowing charged particles toescape the Sun, becoming part of the solar wind
question
Which of the following statements about the sunspot cycle is not true?
answer
C.) The rate of nuclear fusion in the Sun peaks about every 11 years.
question
What processes are involved in the sunspot cycle?
answer
C.) The winding of magnetic field lines due to differential rotation
question
What observations characterize solar maximum?
answer
C.) We see many sunspots on the surface of the Sun.
question
Humans have not sent a spacecraft into the interior of the Sun to confirm any models of the interior.What evidence then do we have to support our current ideas about the solar interior?
answer
B)solar neutrinos
