- #1

CAF123

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## Homework Statement

I have to show that the Planck radiation formula reduces to the Rayleigh-Jeans formula in the classical limit for blackbodies.

## The Attempt at a Solution

I can easily show it using power series expansion of [itex] e^{(hc/\lambda kT)}[/itex] but I don't understand really why using a power series approximation makes something tend to the classical limit?

Similarly, for [itex] E_k = mc^2(\gamma -1) [/itex] tending to [itex] \frac{mv^2}{2} [/itex], in the classical limit. The results are clear, I just don't understand why using a power series actually works.

Many thanks.