 
Summary: 5ôjuéô'ri 
Physics 408  Exam 2 Name_________________________________________
You are graded on your work, with partial credit where it is deserved.
Please give clear, wellorganized solutions.
h = 6.63 x i0' J s {Planck's constant] k = 1.38 x 1023 J/K [Boltzmann constant]
= 5.67 x 108
2W
[StefanBoltzmann constant} c = 3.00 x 10 rn/s [speed of light]
rnK
1
(ak)
=
e ±1
1. The distance between the Earth and the Sun is R = 1.50 x 1011 m, and the radius of the Sun is
r = 6.96 x 108 m. The radiant energy flux (or intensity) of sunlight at the position of the Earth is
S=solarconstant=1.36x103 .
m
(a) (9) Calculate the total rate of energy generation of the Sun in J/s .
((3y j
(b) (9) Recalling the StefanBoltzmann law, energy flux from perfect blackbody = B T4, calculate the temperature at
