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Multiple Choice Quiz
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Modern optical telescopes
A)utilize huge, finely ground lenses that can be up to 5 meters in diameter.
B)if not adequately adjusted, will produce distorted images from the huge lenses that can sag under their own weight.
C)use concave mirrors instead of lenses.
D)tend to give better results when the stars are twinkling, indicating the atmosphere is perfectly still and clear.

Which of the following is not an advantage of very large telescopes?
A)Magnification of the most faint stars so that they appear bigger than simple points of light.
B)The ability to resolve small details on certain astronomical objects, such as planets.
C)The ability to collect more light that can be used for analysis (such as spectrographic analysis) of previous known objects.
D)The ability to detect very faint objects that cannot be seen otherwise.

Analyzing the spectra of stars, the hottest stars are
D)there is no correlation between star color and temperature.

The Zeeman effect
A)allows the relative motion of stars to be detected.
B)allows magnetic fields among stars and matter in space to be detected.
C)is useful in determining the chemical composition of stars.
D)provides the theoretical basis for determining the temperatures of stars based on their spectra.

Our sun
A)is a fairly average and typical star.
B)in terms of mass, is composed primarily of hydrogen and helium.
C)has a volume so large that it could hold over a million earths.
D)all of the above are true.

Which of the following is not a phenomenon found above and beyond the photosphere of the sun?
C)the corona
D)the solar wind

A)is associated with the aurora borealis but not the aurora australis.
B)is due to human-made and volcanic pollutants in the lower atmosphere.
C)is due to diffuse streams of solar particles interacting with the upper atmosphere.
D)is due to micrometeorites burning up as they enter the atomosphere.

Sunspots may have temperatures around
A)500 K.
B)5,000 K.
C)50,000 K.
D)500,000 K.

Sunspot cycles
A)are correlated with changes in the energy output of the sun.
B)did not have any noticeable effect on earth-based phenomena before the invention of modern electronic equipment.
C)do not affect the intensity of the aurora as seen on the earth.
D)increased dramatically in number and intensity during the late 1600s, leading to the "Little Ice Age".

In the interior of the sun
A)atoms can maintain their electrons, but they are unable to form compounds.
B)the density of matter is thought to be almost ten times that of lead on the earth.
C)the estimate temperature is 2 million K.
D)free electrons cannot exist as they are quickly annihilated by positrons.

Most stars give off energy
A)by nuclear fission or elements heavier than carbon.
B)by the proton cycle or the carbon cycle.
C)drawing it from the virtual vacuum through a black hole.
D)by burning hydrogen and giving off water vapor.

A)could not be detected in any stars, due to their extraordinary distance from the earth, until modern telescopes were built in the late twentieth century.
B)is the apparent shift of an object as the observer moves.
C)can be calibrated in terms of light years.
D)all of the above are true.

The differences between the intrinsic and apparent brightnesses of a star can be expressed as
A)mass versus volume.
B)temperature versus color.
C)total energy given off versus brightness seen from the earth.
D)age versus spectral spread.

Cepheid variable stars are valuable to astronomers because
A)they are the only stars that are known to have planets orbiting them.
B)they came in lots of different colors and contain a diversity of elements, thus giving a good sample of the universe.
C)they can be used to find the distance to the star groups in which they were found.
D)they emit natural radio signals that can be employed in interstellar navigation.

The relative positions of the stars in the night sky
A)are absolutely fixed and therefore we can name constellations with certainty.
B)change appreciably over about four thousand years, which is why the ancient. Egyptians named different constellations than those of today.
C)are changing, but very slowly such that appreciable change cannot be observed even over several centuries or even several thousand years.
D)appear to change because the sun moves among them over the course of a year.

The temperature of a star can be found from its
B)position in a galaxy.
C)apparent brightness.
D)doppler shift compared to the apparent brightness.

The color of the hottest stars is

The reason stars less than one-fortieth as massive as the sun are not found is that
A)the internal fission reactions use up all the fuel very quickly.
B)they are so small that they fall into black holes.
C)the gravitational forces in such a small star would not hold it together against the pressure produced by the nuclear reactions in its interior.
D)gravity cannot squeeze the matter sufficiently to produce the temperatures necessary for nuclear fusion reactions.

The Hertzsprung-Russell Diagram
A)is based on the principle that the intrinsic brightnesses of most stars are related to their temperatures.
B)most stars have the same temperature.
C)was developed in the 1950s by two American astronomers working for NASA.
D)while of great utility for most large stars, has proven of little value in classifying small stars like our sun.

The main sequence on the H-R diagram includes
A)about 90 percent of all stars.
B)white dwarfs.
C)red giants.

Stars are believed to originate
A)in clouds composed largely of hydrogen gas.
B)when black holes eject excess matter and energy.
C)when a supernova explode.
D)when a cloud of helium starts to collapse and breaks into constituent protons (hydrogen atoms).

White dwarfs
A)are believed to be very small, perhaps about the size of the earth.
B)contain atoms that have collapsed in the center, yet retain the standard distances between nuclei and electrons.
C)are totally hypothetical stars, based on the best theories, but have never been observed directly.
D)are found only on the far edge of the universe.

A star in the main sequence will maintain a constant size
A)as long as its helium supply holds out.
B)because its tendency to contract is opposed by the pressure of the hot interior.
C)until it is devoured by black holes.
D)provided that gravitational collapse does not overwhelm its photosphere.

A black dwarf
A)is the final end of result of the life cycle of a star like our sun.
B)is a lump of matter that was once a star but has ceased to give off radiation.
C)is a stage after a white dwarf, but the universe is not thought to be old enough for any white dwarf to have become black dwarfs yet.
D)all of the above are true of black dwarfs.

A)are an intermediate stage in the life of most stars.
B)create immense amounts of radiation that are outside of the visible spectrum, so none have ever been observed by naked eye observations.
C)are the result of exploding stars that initially are more than about eight times the sun's mass.
D)explosions are relatively slow, typically taking about three to four million years.

The Physical Universe, 11eOnline Learning Center

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