Unformatted text preview: s as being the number of photons in that mode. For a given frequency, then, we can calculate the partition function: Z = es σ / τ This, however, is just an expansion of a closed form: Z = Now, we can find the average number of photons in a particular mode, or < s > , using the formula for average value of a property: < s > = sP ( s ) = Substituting in for Z and doing some unillustrative algebra yields the final result: < s > = The result is known as the Planck distribution function and gives us the average number of photons in the mode with frequency σ ....
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 Fall '10
 DavidJudd
 Physics, Energy, Statistical Mechanics, Radiation, Black body, Infrared, Thermal radiation, Planck distribution

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