Introduction to modern physics - FSU Physics Department

Frequencies in cavity radiation
cavity radiation = system of standing waves produced by
interference of e.m. waves reflected between cavity walls
many more “modes” per wavelength band
at high frequencies (short wavelengths)
than at low frequencies
• for cavity of volume V, n = (8πV/ 4 )
or n = (8πV/c 3 ) f 2 f
if energy continuous, get equipartition, = kT all modes
have same energy spectral density grows beyond bounds as
f
If energy related to frequency and not continous (E = nhf),
the “Boltzmann factor” e
-E/kT
leads to a suppression of high
frequencies
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