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Two Stefan Boltzmann Laws 
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#1
Apr2412, 07:10 PM

P: 17

In Reif's book Fundamentals of Statistical and Thermal Physics, he labels two formulas as the StefanBoltzmann Law. They are both involve T^4 but the constant is different. In one, on page 376, the law is given as (pi^{2}/15)*(kT)^{4}/(c*hbar)^{3}.
The other, on page 388, is (pi^{2}/60)*(kT)^{4}/(c^{2}*hbar^{3}). The second formula is c/4 times the first. I have looked carefully through the text and I can't see why there should be a difference. What have I overlooked? 


#2
Apr2512, 07:08 AM

P: 2,179

I don't have the book, but probably they are not the same  one is referring to the intensity of emitted radiation, and the other is referring to the energy density of radiation. The two differ by a factor of c/4. Try this:
http://hyperphysics.phyastr.gsu.edu...m/raddens.html 


#3
Apr2512, 08:39 AM

P: 17

Thanks much! I just checked and I think you are right.



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