Non-uniform distribution of low-frequency blackbody radiation inside a spherical cavity

Blackbody radiation inside a closed cavity is nothing other than the electromagnetic fields emitted from those atoms forming the cavity. In this work, these fields are calculated in the non-relativistic classical domain for the purpose of analyzing the distribution of the radiation inside the cavity in the low-frequency limit. Under the assumption that the cavity is a spherical one, the intensity of the blackbody radiation at some frequency is obtained and found to be uniform only in a small region around the center of the cavity. With the help of the theorem of equipartition, the intensity, or the spectrum of the blackbody radiation, is then expressed as a function of the temperature of the cavity and shown to satisfy the familiar Rayleigh-Jeans' law. Some other properties of the blackbody radiation are also discussed.