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Ccds Study Problems Exam 2 Questions And Answers With Verified Solutions Latest Updated 2024
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Ccds Study Problems Exam 2 Questions And Answers With Verified Solutions Latest Updated 2024
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Ccds Study Problems Exam 2 QuestionsAnd Answers With Verified Solutions
Latest Updated 2024
Describe the properties and everyday uses of CCDs (charge coupled devices). -
ANSWER✔✔CCDs contain millions of pixels. They are much more sensitive than
photographic plates and are now used in mosaics, by astronomers, to cover a large
field on the sky. Their everyday uses are in digital cameras and cell phones.
How does the resolution of a telescope above the atmosphere depend on the size of
the mirror? - ANSWER✔✔The larger the mirror, the better the resolution, i.e. the
sharper the images.
How much larger is the Sun than the Earth in diameter? In volume? -
ANSWER✔✔The diameter of the Sun is about 100x the diameter of the Earth.
Thus, the volume of the Sun is about 10^6 x the diameter of the Earth, i.e. if the
Sun were hollow it would take 10^6 Earth-sized objects to fill it.
What is the average density of the Sun? How does this compare with water? -
ANSWER✔✔The average density of the Sun is 1400 kg/m^3. This is similar to
that of water (1000 kg/m^3).
What is hydrostatic equilibrium for the Sun? - ANSWER✔✔Hydrostatic
equilibrium is a balance between the outward gas pressure force in the Sun and the
inward pull of gravity. The Sun supports its own weight by its outward gas
pressure force, so that it is neither contracting nor expanding.
What is thermal equilibrium for the Sun? - ANSWER✔✔Thermal equilibrium is a
state in which the energy radiated by the photosphere of the Sun is replaced by an
internal energy source, nuclear fusion in the core.
What are the central and surface temperatures of the Sun? - ANSWER✔✔The
central temperature of the Sun is about 1.6 x 10^7 K and the temperature in the
photosphere is about 5800 K.
, What are the two most abundant elements in the Sun? - ANSWER✔✔Hydrogen
and helium are the two most abundant elements in the Sun (as well as in the
universe as a whole).
What is the physical state of the material in the Sun? - ANSWER✔✔Below the
photosphere of the Sun, the hydrogen and helium in the Sun are in an ionized state,
i.e. the electrons move freely rather than being bound to a particular nucleus.
What type of particle is a normal hydrogen nucleus? - ANSWER✔✔A normal
hydrogen nucleus is a proton.
What is the energy source of the Sun? Describe the physical process that releases
energy. Discuss where this process occurs in the Sun and why it occurs here. -
ANSWER✔✔The Sun produces energy by the thermonuclear fusion of hydrogen
to helium in its core. Through a series of reactions, four hydrogen nuclei are fused
to produce one helium nucleus plus energy. The mass of a normal helium nucleus
is slightly less than four times the mass of a normal hydrogen nucleus. The lost
mass is converted to an equivalent amount of energy according to the relation
E=mc^2. Nuclear fusion occurs only in the core of the Sun, since it is only there
that the temperature is sufficiently high (T>10^7K). High temperature is required
for nuclear fusion, since nuclei must collide at high speed in order to overcome
their electrical repulsion.
About how long has the Sun been in existence and about how much longer will the
Sun's present nuclear energy reserve last? - ANSWER✔✔The Sun has been in
existence for 5 billion years. The Sun's present hydrogen energy reserve will last
for another 5 billion years.
What mechanisms transport energy in the Sun? Describe each process. Where does
each mechanism dominate? - ANSWER✔✔Energy is transported in the Sun by
both radiation and convection. In radiation, photons random walk outward in the
Sun, carrying energy outward. In convection, hot gas rises and cool gas sinks, also
carrying energy outward. Radiation dominates in the core and the inner envelope
of the Sun. Convection dominates in the outer envelope.
What is the evidence that convection occurs in the Sun? - ANSWER✔✔The
observation of granulation in the Sun's photosphere provides direct evidence of
convection. The bright areas in the granulation pattern are the tops of rising
columns of hotter gas. The dark areas are sinking columns of cooler gas.
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