Problem Set 5
When hydrogen fuses to helium, what fraction of its mass changes to energy?
0.7%
About how hot is the Sun's core?
1.5 x 10^7 K
The time between one sunspot maximum and the next one is about
11 years
How many times more massive is the Sun than the Earth?
300,000
If 6 kg of mass is changed entirely into energy, how much energy is produced? Give the answer in watt-seconds to two significant figures. You may enter the answer in powers of ten notation by replacing " x10y " by "ey", for example 3.1x108 would be written as 3.1e8 in the answer box.
5.4e+17
Spica, the brightest star in the constellation Virgo, has luminosity 5x1029watt. How much mass does it change to energy each second?
5.6 e12
How much energy does a 100-watt light bulb emit in one minute? Give the answer as a number of watt-seconds.
6000
About how hot is the Sun's photosphere?
6000 K
If a star turns 10^25 kg of matter into energy in one second, how much energy does it produce in that second?
9x10^41 watt-seconds
Neutrinos have never been detected experimentally.
False
Sunspots appear dark because they are hotter than the surrounding gas of the photosphere
False
The density and temperature in the solar corona are much higher than in the photosphere.
False
The proton-proton chain releases energy because mass is created in the process.
False
There are as many absorption lines in the solar spectrum as there are elements present in the Sun.
False
The most abundant element in the Sun is hydrogen.
True
The density of the Sun is closest to that of which of the objects listed below?
a comet
The time between successive sunspot maxima is roughly
a decade
Sunspots are
cooler
Compared to the Sun's corona, its photosphere is
denser and cooler
The primary source of the Sun's energy is
fusion of light nuclei to make heavier ones
The Sun is a stable star in which
gravity balances the force from pressure
The Sun's energy is produced by the fusion of
hydrogen and helium
The Sun spins on its axis roughly once each
month
Compared with Earth's diameter, the Sun's diameter is about
one hundred times larger
The visible light we see from the Sun comes from what part of the Sun?
photosphere
The density of the Sun is closest to the density of
water
