Is Plancks function a distribution one?

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Planck's law is often referred to as a distribution function, but it differs from true probability distribution functions like the Maxwell-Boltzmann distribution, which integrates to 1. Instead, Planck's law is normalized to total power per unit area, making it not a probability distribution. While it can be considered a distribution in a broader sense, its specific form provides radiance rather than a probability density function. The integral of Planck's function does not equal 1 due to the factor used to convert it into irradiance or radiance. Thus, it is accurate to treat Planck's law as a distribution while acknowledging its unique normalization.
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In many textbooks Plancks law or function is also referred to as Plancks distribution.
But is it a true distribution function?

I was reading a textbook where it was describing Maxwell-Boltzmann distribution
(which is a true distribution function since its integral across the range equals 1 )
and a few pages later it was comparing it with Plancks distribution pointing out how similar they look.

But is Plancks law a true distribution function?
 
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Usually Planck's law is defined so that it is normalized to total power per unit area, rather than 1, which would have made it a probability distribution. But if you ignore the probability definition, it is a distribution.
 
mathman said:
Usually Planck's law is defined so that it is normalized to total power per unit area, rather than 1, which would have made it a probability distribution. But if you ignore the probability definition, it is a distribution.

But the form of the Plancks function that gives radiance (Energy/time/area/steradian/wavelength or frequency) is not a probability density function,right?
 
mathman said:
Usually Planck's law is defined so that it is normalized to total power per unit area, rather than 1, which would have made it a probability distribution. But if you ignore the probability definition, it is a distribution.

Ok,I got what you said.It is a distribution and should be treated as one.The reason its integral is not 1 is because it is multiplied by a factor to give irradiance, radiance etc.

Thanks.
 
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