Where would a brown dwarf be located on an H-R diagram?
A) above and to the left of the highest part of the main sequence
B) in the upper right...
We do not know for certain whether the general trends we observe in stellar birth masses also apply to brown dwarfs. But if they do, then which of the following would be true?
We do not know for certain whether the general trends we observe in stellar birth masses also apply to brown dwarfs. But if they do, then which of the...
Consider a large molecular cloud that will give birth to a cluster of stars. Which of the following would you expect to be true?
Consider a large molecular cloud that will give birth to a cluster of stars. Which of the following would you expect to be true?
A) All the...
If a star is extremely massive (well over 100 solar masses), why isn't it likely to survive for long?
If a star is extremely massive (well over 100 solar masses), why isn't it likely to survive for long?
A) It explodes as a supernova after just...
The core of a protostar that will eventually become a brown dwarf shrinks until
The core of a protostar that will eventually become a brown dwarf shrinks until
A) the type of pressure called degeneracy pressure becomes important.
B)...
The surface of a protostar radiates energy while its core
The surface of a protostar radiates energy while its core
A) shrinks and cools.
B) shrinks and maintains a constant temperature.
C) shrinks and heats.
D)...
Why does the rotation of a protostar slow down over time?
Why does the rotation of a protostar slow down over time?
A) All rotating objects slow down over time.
B) Magnetic fields can transfer angular...
Where does a 1-solar-mass protostar appear on an H-R diagram?
Where does a 1-solar-mass protostar appear on an H-R diagram?
A) to the right of the main sequence, and lower down than the Sun
B) to the right...
Generally speaking, how does the surface temperature and luminosity of a protostar compare to the surface temperature and luminosity of the main-sequence star it becomes?
Generally speaking, how does the surface temperature and luminosity of a protostar compare to the surface temperature and luminosity of the main-sequence...
Close binary star systems are thought to form when
Close binary star systems are thought to form when
A) two interstellar gas clouds happen to contract so close together that there's no room for a...
Angular momentum plays an important role in star formation. Which of the following characteristics of a protostellar system is probably not strongly affected by the star's angular momentum?
Angular momentum plays an important role in star formation. Which of the following characteristics of a protostellar system is probably not strongly...
According to current understanding, how did the first generation of stars differ from stars born today?
According to current understanding, how did the first generation of stars differ from stars born today?
A) They contained much more hydrogen...
Which process is required to allow a gravitationally-collapsing gas cloud to continue to collapse?
Which process is required to allow a gravitationally-collapsing gas cloud to continue to collapse?
A) The cloud must trap most of its thermal...
Under which circumstances can you be sure that the thermal pressure within a gas cloud is increasing?
Under which circumstances can you be sure that the thermal pressure within a gas cloud is increasing?
A) The cloud's temperature and density...
What happens to the visible light radiated by stars located within a dusty gas cloud?
What happens to the visible light radiated by stars located within a dusty gas cloud?
A) It is blocked by dust and its energy is thereby lost.
B)...
How do we learn the chemical composition of the interstellar medium?
How do we learn the chemical composition of the interstellar medium?
A) We make an educated guess based on the Sun's composition.
B) By studying...
About what percentage of the mass of a molecular cloud is in the form of dust?
About what percentage of the mass of a molecular cloud is in the form of dust?
A) 1%
B) 10%
C) 50%
D) 98%
Answer: ...
Which two processes can generate energy to help a star or gas cloud maintain its internal thermal pressure?
Which two processes can generate energy to help a star or gas cloud maintain its internal thermal pressure?
A) nuclear fusion and nuclear fission
B)...
Which of the following statements about brown dwarfs is not true?
Which of the following statements about brown dwarfs is not true?
A) Brown dwarfs eventually collapse to become white dwarfs.
B) Brown dwarfs...
The vast majority of stars in a newly formed star cluster are
The vast majority of stars in a newly formed star cluster are
A) very high-mass, type O and B stars.
B) red giants.
C) about the same mass as our...
What is the approximate range of masses that newborn main-sequence stars can have?
What is the approximate range of masses that newborn main-sequence stars can have?
A) 0.001 to 150 solar masses
B) 0.1 to 1,000 solar masses
C)...
Which star spends the longest time in the protostellar phase of life?
Which star spends the longest time in the protostellar phase of life?
A) a 1-solar-mass star
B) a 2-solar-mass star
C) a 3-solar-mass star
D)...
Approximately what core temperature is required before hydrogen fusion can begin in a star?
Approximately what core temperature is required before hydrogen fusion can begin in a star?
A) 10,000 K
B) 10 million K
C) 1 billion K
D) 10...
When does a protostar become a main-sequence star?
When does a protostar become a main-sequence star?
A) when the rate of hydrogen fusion becomes high enough to balance the rate at which the...
What can we learn about a star from a life track on an H-R diagram?
What can we learn about a star from a life track on an H-R diagram?
A) the star's age
B) the surface temperature and luminosity the star will...
What law explains why a collapsing cloud usually forms a protostellar disk around a protostar?
What law explains why a collapsing cloud usually forms a protostellar disk around a protostar?
A) Kepler's third law
B) the universal law of...
Which of the following phenomena is not commonly associated with the star formation process?
Which of the following phenomena is not commonly associated with the star formation process?
A) the formation of a spinning disk of material...
What is a protostar?
What is a protostar?
A) a star that has planets
B) an intermediate-mass star
C) a star that is still in the process of forming
D) a star in...
Which of the following statements is probably true about the very first stars in the universe?
Which of the following statements is probably true about the very first stars in the universe?
A) They were made only from hydrogen and helium.
B)...
What effect are magnetic fields thought to have on star formation in molecular clouds?
What effect are magnetic fields thought to have on star formation in molecular clouds?
A) They can help resist gravity, so that more total mass...
What kind of gas cloud is most likely to give birth to stars?
What kind of gas cloud is most likely to give birth to stars?
A) a hot, dense gas cloud
B) a cold, dense gas cloud
C) a cold, low-density gas...
Most interstellar clouds remain stable in size because the force of gravity is opposed by ________ within the cloud.
Most interstellar clouds remain stable in size because the force of gravity is opposed by ________ within the cloud.
A) degeneracy pressure
B)...
Suppose you look by eye at a star near the edge of a dusty interstellar cloud. The star will look ________ than it would if it were outside the cloud.
Suppose you look by eye at a star near the edge of a dusty interstellar cloud. The star will look ________ than it would if it were outside the cloud.
A)...
Which part of the electromagnetic spectrum generally gives us our best views of stars forming in dusty clouds?
Which part of the electromagnetic spectrum generally gives us our best views of stars forming in dusty clouds?
A) visible light
B) ultraviolet
C)...
Interstellar dust consists mostly of
Interstellar dust consists mostly of
A) ozone "smog."
B) microscopic particles of carbon and silicon.
C) hydrogen and helium atoms.
D) tiny...
Which of the following types of molecule is the most abundant in an interstellar molecular cloud?
Which of the following types of molecule is the most abundant in an interstellar molecular cloud?
A) CO
B) H2O
C) H2
D) NH3
Answer: ...
The interstellar clouds called molecular clouds are
The interstellar clouds called molecular clouds are
A) the clouds in which elements such as carbon, nitrogen, and oxygen are made.
B) clouds...
What do we mean by the interstellar medium?
What do we mean by the interstellar medium?
A) The gas and dust that lies in between the stars in the Milky Way Galaxy.
B) The dust that fills...
Where would a brown dwarf be located on an H-R diagram?
Where would a brown dwarf be located on an H-R diagram?
A) upper right
B) on the lower part of the main sequence
C) below and to the right of...
What is the eventual fate of a brown dwarf?
What is the eventual fate of a brown dwarf?
A) It remains the same forever.
B) It gradually cools down and becomes ever dimmer.
C) It gradually...
What prevents a brown dwarf from undergoing nuclear fusion?
What prevents a brown dwarf from undergoing nuclear fusion?
A) Degeneracy pressure halts the contraction of a protostar so the core never becomes...
Which of the following discoveries, if they existed, would necessitate a reevaluation of our ideas of stellar formation?
Which of the following discoveries, if they existed, would necessitate a reevaluation of our ideas of stellar formation?
A) a cluster of stars...
For every star with a mass greater than 10 solar masses, about how many stars are there with masses less than a solar mass?
For every star with a mass greater than 10 solar masses, about how many stars are there with masses less than a solar mass?
A) 1
B) 3
C) 10
D)...
No stars have been found with masses greater than 300 times our Sun because
No stars have been found with masses greater than 300 times our Sun because
A) molecular clouds do not have enough material to form such massive...
What is the greatest mass a newborn star can have
What is the greatest mass a newborn star can have
A) 10 solar masses.
B) 20 solar masses.
C) 50 solar masses.
D) 150 solar masses.
E) 300 solar...
What are the letters that follow the spectral sequence OBAFGKM?
What are the letters that follow the spectral sequence OBAFGKM?
A) NP
B) YZ
C) LT
D) CD
E) UV
Answer: ...
What is the smallest mass a newborn star can have?
What is the smallest mass a newborn star can have?
A) 8 times the mass of Jupiter
B) 80 times the mass of Jupiter
C) 800 times the mass of Jupiter
D)...
About how many times more luminous than our Sun is a young solar mass protostar just beginning convective contraction?
About how many times more luminous than our Sun is a young solar mass protostar just beginning convective contraction?
A) 2-5
B) 5-10
C) 10-100
D)...
When does hydrogen first begin to fuse into helium in the star formation process?
When does hydrogen first begin to fuse into helium in the star formation process?
A) when the cloud first begins to contract
B) when the thermal...
What happens to the surface temperature and luminosity when a protostar radiatively contracts?
What happens to the surface temperature and luminosity when a protostar radiatively contracts?
A) Its surface temperature and luminosity increase.
B)...
What happens to the surface temperature and luminosity when a protostar undergoes convective contraction?
What happens to the surface temperature and luminosity when a protostar undergoes convective contraction?
A) Its surface temperature and luminosity...
What happens to the surface temperature and luminosity when gravity first assembles a protostar from a collapsing cloud?
What happens to the surface temperature and luminosity when gravity first assembles a protostar from a collapsing cloud?
A) Its surface temperature...
When does a star become a main-sequence star?
When does a star become a main-sequence star?
A) when the protostar assembles from a molecular cloud
B) the instant when hydrogen fusion first...
What species absorbs photons in a protostar's outer layers?
What species absorbs photons in a protostar's outer layers?
A) H
B) H2
C) H+
D) H-
E) dust
Answer: ...
What is the range of timescales for star formation?
What is the range of timescales for star formation?
A) from 1 million years for the most massive stars up to 10 million years for the least...
How long does the protostellar stage last for a star like our Sun?
How long does the protostellar stage last for a star like our Sun?
A) 1 million years
B) 3 million years
C) 10 million years
D) 30 million years
E)...
When does a protostar become a true star?
When does a protostar become a true star?
A) when the star is 1 million years old
B) when the central temperature reaches 1 million Kelvin
C)...
Which of the following may be caused by a protostellar disk?
Which of the following may be caused by a protostellar disk?
A) protostellar jets
B) protostellar winds
C) accretion of material onto the star
D)...
What happens to the rotation of a molecular cloud as it collapses to form a star?
What happens to the rotation of a molecular cloud as it collapses to form a star?
A) The rotation rate remains the same and results in stellar...
When is thermal energy trapped in the dense center of a cloud?
When is thermal energy trapped in the dense center of a cloud?
A) when the gravity becomes so strong that photons cannot escape
B) when excited...
What is the minimum temperature for a cloud to excite emission lines from H2?
What is the minimum temperature for a cloud to excite emission lines from H2?
A) 10 K
B) 30 K
C) 100 K
D) 300 K
E) 1000 K
Answer: ...
Why do we think the first generation of stars would be different from stars born today?
Why do we think the first generation of stars would be different from stars born today?
A) Without heavy elements, the clouds could not reach...
What is the likely reason that we cannot find any examples of the first generation stars?
What is the likely reason that we cannot find any examples of the first generation stars?
A) The first generation stars are too faint to be...
How do astronomers infer the presence of magnetic fields in molecular clouds?
How do astronomers infer the presence of magnetic fields in molecular clouds?
A) by measuring the amount of interstellar reddening
B) by measuring...
What property of a molecular cloud does not counteract gravitational contraction?
What property of a molecular cloud does not counteract gravitational contraction?
A) thermal pressure
B) turbulent motions
C) magnetic fields
D)...
Calculations show that gravity begins to overcome thermal pressure in clouds that are
Calculations show that gravity begins to overcome thermal pressure in clouds that are
A) less massive than the Sun.
B) more massive than the...
What prevents the pressure from increasing as a cloud contracts due to its gravity?
What prevents the pressure from increasing as a cloud contracts due to its gravity?
A) As the cloud becomes denser, gravity becomes stronger...
The gravitational force in a molecular cloud depends on
The gravitational force in a molecular cloud depends on
A) density only.
B) temperature only.
C) density and temperature.
D) composition.
E)...
The thermal pressure of a gas depends on
The thermal pressure of a gas depends on
A) density only.
B) temperature only.
C) density and temperature.
D) composition.
E) gravity.
An...
What happens to the visible radiation produced by new stars within a molecular cloud?
What happens to the visible radiation produced by new stars within a molecular cloud?
A) It escapes the cloud completely.
B) It is absorbed...
If you wanted to observe stars behind a molecular cloud, in what wavelength of light would you most likely observe?
If you wanted to observe stars behind a molecular cloud, in what wavelength of light would you most likely observe?
A) ultraviolet
B) visible
C)...
What is interstellar reddening?
What is interstellar reddening?
A) Interstellar dust absorbs more red light than blue light, making stars appear redder than their true color.
B)...
The typical size of an interstellar dust grain is
The typical size of an interstellar dust grain is
A) 1 angstrom.
B) 1 nanometer.
C) 1 micrometer.
D) 1 millimeter.
E) 1 centimeter.
Answe...
The most abundant molecule in molecular clouds is
The most abundant molecule in molecular clouds is
A) H2.
B) He2.
C) CO.
D) H2O.
E) HHe.
Answer: ...
The typical density and temperature of molecular clouds are
The typical density and temperature of molecular clouds are
A) 100 molecules per cubic centimeter, 10-30 Kelvin.
B) 300 molecules per cubic...
What percentage of a molecular cloud's mass is interstellar dust?
What percentage of a molecular cloud's mass is interstellar dust?
A) 1%
B) 2%
C) 28%
D) 50%
E) 1-50%, depending on the mass of the molecular...
By mass, the interstellar medium in our region of the Milky Way consists of
By mass, the interstellar medium in our region of the Milky Way consists of
A) 70% Hydrogen, 30% Helium.
B) 70% Hydrogen, 28% Helium, 2% heavier...
Astronomers estimate that new stars form in our galaxy at the rate of about
Astronomers estimate that new stars form in our galaxy at the rate of about
A) one per year.
B) a few (2-3) per year.
C) ten per year.
D) 20-30...
Which of the following is not a major reason why astronomers would like an observatory on the far side of the Moon?
Which of the following is not a major reason why astronomers would like an observatory on the far side of the Moon?
A) Telescopes on the Moon...
Consider two future observatories in space. Observatory X consists of a single 50-meter telescope. Observatory Y is an interferometer consisting of five 10-meter telescopes, spread out over a region 100 meters across. Which observatory can detect dimmer stars, and which one can see more detail in its images?
Consider two future observatories in space. Observatory X consists of a single 50-meter telescope. Observatory Y is an interferometer consisting of...
Which of the following telescopes would benefit most from adaptive optics?
Which of the following telescopes would benefit most from adaptive optics?
A) The Keck I Telescope on Mauna Kea.
B) The Hubble Space Telescope.
C)...
The Chandra X-Ray Observatory must operate in space because
The Chandra X-Ray Observatory must operate in space because
A) X rays are too dangerous to be allowed on the ground.
B) X rays do not penetrate...
Which of the following is not an advantage of the Hubble Space Telescope over ground-based telescopes?
Which of the following is not an advantage of the Hubble Space Telescope over ground-based telescopes?
A) It is closer to the stars.
B) Stars...
The stars in our sky twinkle in brightness and color because of
The stars in our sky twinkle in brightness and color because of
A) turbulence in the Earth's atmosphere.
B) rapid changes in the brightnesses...
Which of the following is not a reason why telescopes tend to be built on mountaintops that are relatively far from cities and are in regions with dry climates?
Which of the following is not a reason why telescopes tend to be built on mountaintops that are relatively far from cities and are in regions with dry...
Which of the following studies is best suited to astronomical observations that fall into the category called timing?
Which of the following studies is best suited to astronomical observations that fall into the category called timing?
A) studying how different...
Which of the following best describes why radio telescopes are generally much larger in size than telescopes designed to collect visible light?
Which of the following best describes why radio telescopes are generally much larger in size than telescopes designed to collect visible light?
A)...
Which of the following best describes the development of astronomical telescopes over the past 60 years?
Which of the following best describes the development of astronomical telescopes over the past 60 years?
A) Over the 60-year period, telescopes...
How does the light-collecting area of an 8-meter telescope compare to that of a 2-meter telescope?
How does the light-collecting area of an 8-meter telescope compare to that of a 2-meter telescope?
A) The 8-meter telescope has 16 times the...
Which of the following best describes the principle advantage of CCDs over photographic film?
Which of the following best describes the principle advantage of CCDs over photographic film?
A) CCDs allow long exposures (e.g., minutes or...
Suppose you point your telescope at a distant object. Which of the following is not an advantage of taking a photograph of the object through the telescope as compared to just looking at the object through the telescope?
Suppose you point your telescope at a distant object. Which of the following is not an advantage of taking a photograph of the object through the telescope...
The angular separation of two stars is 0.1 arcseconds and you photograph them with a telescope that has an angular resolution of 1 arcsecond. What will you see?
The angular separation of two stars is 0.1 arcseconds and you photograph them with a telescope that has an angular resolution of 1 arcsecond. What will...
Suppose you have two small photographs of the Moon. Although both look the same at small size, when you blow them up to poster size one of them still looks sharp while the other one becomes fuzzy (grainy) looking. Which of the following statements is true?
Suppose you have two small photographs of the Moon. Although both look the same at small size, when you blow them up to poster size one of them still...
What is the purpose of interferometry?
What is the purpose of interferometry?
A) It allows two or more small telescopes to achieve the angular resolution of a much larger telescope.
B)...
Which of the following wavelength regions can be studied with telescopes on the ground?
Which of the following wavelength regions can be studied with telescopes on the ground?
A) radio, visible, and very limited portions of the...
What is the purpose of adaptive optics?
What is the purpose of adaptive optics?
A) It reduces blurring caused by atmospheric turbulence for telescopes on the ground.
B) It allows several...
Which of the following effects is caused by atmospheric turbulence?
Which of the following effects is caused by atmospheric turbulence?
A) twinkling of stars
B) light pollution
C) magnification of images
D) diffraction...
What do astronomers mean by light pollution?
What do astronomers mean by light pollution?
A) Light pollution is a type of air pollution created by lightweight gases such as hydrogen and...
Which of the following is always true about images captured with X-ray telescopes?
Which of the following is always true about images captured with X-ray telescopes?
A) They are always shown with colors that are not the true...
Suppose you want to determine the chemical composition of a distant planet or star. Which of the following will be most useful to have?
Suppose you want to determine the chemical composition of a distant planet or star. Which of the following will be most useful to have?
A) high...
Which of the following is not one of the three main categories of observation generally used by astronomers?
Which of the following is not one of the three main categories of observation generally used by astronomers?
A) filtering to look at just a...
What do we mean by the diffraction limit of a telescope?
What do we mean by the diffraction limit of a telescope?
A) It describes the farthest distance to which the telescope can see.
B) It is the...
Which of the following statements best describes the difference between a refracting telescope and a reflecting telescope?
Which of the following statements best describes the difference between a refracting telescope and a reflecting telescope?
A) A refracting telescope...
What is a CCD?
What is a CCD?
A) It is an electronic detector that can be used in place of photographic film for making images.
B) It is an abbreviation for...
What is the angular resolution of the human eye?
What is the angular resolution of the human eye?
A) about 1 degree
B) about 1 arcsecond (1/3600 of a degree)
C) about 1 arcminute, or 1/60 of...
What does angular resolution measure?
What does angular resolution measure?
A) the angular size of the smallest features that the telescope can see
B) the brightness of an image
C)...
Which of the following best describes what we mean by the focal plane of a telescope?
Which of the following best describes what we mean by the focal plane of a telescope?
A) It is the upper surface of the telescope's primary...
In what wavelength range was interferometry first routinely used?
In what wavelength range was interferometry first routinely used?
A) radio
B) infrared
C) optical
D) ultraviolet
E) X-ray
Answer: ...
The largest effective telescope, created by radio interferometry, is the size of
The largest effective telescope, created by radio interferometry, is the size of
A) several football fields, in a natural depression in Puerto...
What does the technique of interferometry allow?
What does the technique of interferometry allow?
A) It allows two or more telescopes to obtain a total light-collecting area much larger than...
In what part of the electromagnetic spectrum do the biggest telescopes on Earth operate?
In what part of the electromagnetic spectrum do the biggest telescopes on Earth operate?
A) radio
B) infrared
C) visible
D) ultraviolet
E) ...
At which wavelength range is there no current or planned space observatory?
At which wavelength range is there no current or planned space observatory?
A) radio
B) infrared
C) visible
D) X-ray
E) gamma-ray
Answer:...
Telescopes operating at this wavelength must be cooled to observe faint astronomical objects.
Telescopes operating at this wavelength must be cooled to observe faint astronomical objects.
A) radio
B) extreme infrared
C) visible
D) X-ray
E)...
Which of the following wavelength regions cannot be studied with telescopes on the ground?
Which of the following wavelength regions cannot be studied with telescopes on the ground?
A) radio waves
B) ultraviolet
C) X rays
D) both B...
Which of the following is not an advantage of the Hubble Space Telescope over ground-based telescopes?
Which of the following is not an advantage of the Hubble Space Telescope over ground-based telescopes?
A) It is closer to the stars.
B) Stars...
Why do astronomers need different telescope designs to observe across the electromagnetic spectrum?
Why do astronomers need different telescope designs to observe across the electromagnetic spectrum?
A) New telescopes incorporate new technology...
Which of the following is not a good reason to place observatories on remote mountain tops?
Which of the following is not a good reason to place observatories on remote mountain tops?
A) to reduce light pollution
B) to reduce light...
What is an artificial star?
What is an artificial star?
A) a point of light in Earth's atmosphere created by a laser for the purpose of monitoring atmospheric fluctuations
B)...
What is the purpose of adaptive optics?
What is the purpose of adaptive optics?
A) to improve the angular resolution of telescopes in space
B) to eliminate the distorting effects of...
What causes stars to twinkle?
What causes stars to twinkle?
A) It is intrinsic to the stars-their brightness varies as they expand and contract.
B) variations in the absorption...
What do astronomers mean by light pollution?
What do astronomers mean by light pollution?
A) Light pollution refers to pollution caused by light industry as opposed to heavy industry.
B)...
Which of the following is always true about images captured with X-ray telescopes?
Which of the following is always true about images captured with X-ray telescopes?
A) They are always very pretty.
B) They are always displayed...
Which of the following studies is best suited to a time monitoring experiment?
Which of the following studies is best suited to a time monitoring experiment?
A) studying how different stars differ in their chemical compositions
B)...
What is meant by spectral resolution?
What is meant by spectral resolution?
A) It is a measure of how much energy an object emits in different parts of the electromagnetic spectrum.
B)...
Which of the following could not be determined by an observation that uses only spectroscopy?
Which of the following could not be determined by an observation that uses only spectroscopy?
A) the chemical composition of a distant star
B)...
Which of the following could not be measured by an observation that uses only imaging?
Which of the following could not be measured by an observation that uses only imaging?
A) the rate at which a variable star brightens and dims
B)...
What do we mean by the diffraction limit of a telescope?
What do we mean by the diffraction limit of a telescope?
A) It is the maximum size to which any telescope can be built.
B) It describes the...
Currently, the largest optical telescope mirrors have a diameter of
Currently, the largest optical telescope mirrors have a diameter of
A) 1 m.
B) 2 m.
C) 5 m.
D) 10 m.
E) 100 m.
Answer: D...
Which of the following statements best describes the two principal advantages of telescopes over eyes?
Which of the following statements best describes the two principal advantages of telescopes over eyes?
A) Telescopes can collect far more light...
Order the following in order of increasing efficiency of detecting photons of visible light.
Order the following in order of increasing efficiency of detecting photons of visible light.
A) eye, photographic film, CCD
B) photographic...
Which of the following is a principal advantage of CCDs over photographic film?
Which of the following is a principal advantage of CCDs over photographic film?
A) CCDs allow long exposures (e.g., minutes or hours), and film...
Suppose the angular separation of two stars is smaller than the angular resolution of your eyes. How will the stars appear to your eyes?
Suppose the angular separation of two stars is smaller than the angular resolution of your eyes. How will the stars appear to your eyes?
A)...
Which of the following statements about light focusing is not true?
Which of the following statements about light focusing is not true?
A) In a healthy eye, light is focused on the retina.
B) Film should be placed...
An atom which has 4 protons and 6 neutrons will be electrically neutral if it contains
An atom which has 4 protons and 6 neutrons will be electrically neutral if it contains
A) 4 electrons.
B) 6 electrons.
C) 10 electrons.
D) at least...
Consider an atom of carbon in which the nucleus contains 6 protons and 7 neutrons. What is its atomic number and atomic mass number?
Consider an atom of carbon in which the nucleus contains 6 protons and 7 neutrons. What is its atomic number and atomic mass number?
A) atomic...
Suppose that two stars are identical in every way—for example, same distance, same mass, same temperature, same chemical composition, and same speed relative to Earth—except that one star rotates faster than the other. Spectroscopically, how could you tell the stars apart?
Suppose that two stars are identical in every way—for example, same distance, same mass, same temperature, same chemical composition, and same speed...
Studying a spectrum from a star can tell us a lot. All of the following statements are true except one. Which statement is not true?
Studying a spectrum from a star can tell us a lot. All of the following statements are true except one. Which statement is not true?
A) The...
If we observe one edge of a planet to be redshifted and the opposite edge to be blueshifted, what can we conclude about the planet?
If we observe one edge of a planet to be redshifted and the opposite edge to be blueshifted, what can we conclude about the planet?
A) We must...
Suppose that Star X and Star Y both have redshifts, but Star X has a larger redshift than Star Y. What can you conclude?
Suppose that Star X and Star Y both have redshifts, but Star X has a larger redshift than Star Y. What can you conclude?
A) Star X is moving...
Laboratory measurements show hydrogen produces a spectral line at a wavelength of 486.1 nanometers (nm). A particular star's spectrum shows the same hydrogen line at a wavelength of 486.0 nm. What can we conclude?
Laboratory measurements show hydrogen produces a spectral line at a wavelength of 486.1 nanometers (nm). A particular star's spectrum shows the same...
All of the following statements about the Sun's corona are true. Which one explains why it is a source of X rays?
All of the following statements about the Sun's corona are true. Which one explains why it is a source of X rays?
A) The temperature of the...
The planet Neptune is blue in color. How would you expect the spectrum of visible light from Neptune to be different from the visible-light spectrum of the Sun?
The planet Neptune is blue in color. How would you expect the spectrum of visible light from Neptune to be different from the visible-light spectrum...
Betelgeuse is the bright red star representing the left shoulder of the constellation Orion. All the following statements about Betelgeuse are true. Which one can you infer from its red color?
Betelgeuse is the bright red star representing the left shoulder of the constellation Orion. All the following statements about Betelgeuse are true....
Which of the following statements about thermal radiation is always true?
Which of the following statements about thermal radiation is always true?
A) A hot object emits more radiation per unit surface area than a...
No object produces a perfect thermal radiation spectrum, but many objects produce close approximations. Which of the following would not produce a close approximation to a thermal radiation spectrum?
No object produces a perfect thermal radiation spectrum, but many objects produce close approximations. Which of the following would not produce a close...
Which of the following conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space?
Which of the following conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space?
A) The cloud is extremely...
Which of the following statements about electrons is not true?
Which of the following statements about electrons is not true?
A) Electrons orbit the nucleus rather like planets orbiting the Sun.
B) Within...
Consider an atom of oxygen in which the nucleus contains 8 protons and 8 neutrons. If it is doubly ionized, what is the charge of the oxygen ion and how many electrons remain in the ion?
Consider an atom of oxygen in which the nucleus contains 8 protons and 8 neutrons. If it is doubly ionized, what is the charge of the oxygen ion and...
Suppose you had molecular oxygen (O2) chilled enough so that it was in liquid form. Which of the following best describes the phase changes that would occur as you heated the liquid oxygen to high temperature?
Suppose you had molecular oxygen (O2) chilled enough so that it was in liquid form. Which of the following best describes the phase changes that would...
Each of the following describes an "Atom 1" and an "Atom 2." In which case are the two atoms different isotopes of the same element?
Each of the following describes an "Atom 1" and an "Atom 2." In which case are the two atoms different isotopes of the same element?
A) Atom...
Which of the following statements about X rays and radio waves is not true?
Which of the following statements about X rays and radio waves is not true?
A) X rays travel through space faster than radio waves.
B) X rays...
Which of the following best describes why we say that light is an electromagnetic wave?
Which of the following best describes why we say that light is an electromagnetic wave?
A) Light can be produced only by electric or magnetic...
Suppose a photon has a frequency of 300 million hertz (300 megahertz). What is its wavelength?
Suppose a photon has a frequency of 300 million hertz (300 megahertz). What is its wavelength?
A) 1 meter
B) 1/300,000 meter
C) 300 million...
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