The temperature of the Sun’s surface (the so-called photosphere) is about 5500 C. Assume that the Sun’s surface is pretty close to a perfect black-body emitter.
(a) At what wavelength does the peak intensity of Sun’s radiation lie?
(b) Estimate the total power radiated by Sun into space. The Sun’s radius is 7.0E10^8 m.
(c) This radiated energy comes from a decrease in the Sun’s internal energy, which as
we know is equivalent to a decrease in mass. From the relativistic identity, how many
kilograms of mass are lost per second?
(d) From the amount of radiated energy, determine the power per unit area arriving at theEarth, 1.5E10^11 m away.
(e) The average power consumption in the US is about 2.9 TW. The best solar panels
todays convert about 20% of incident radiation into electricity. Estimate the area that
would need to be covered by solar panels if all this consumption were to be satisfied by
solar energy. Express your answer (i) in square kilometers and (ii) in fraction of the land
area of California.
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