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.

中文翻译：

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球体内腔内低频黑体辐射的不均匀分布。

封闭腔内的黑体辐射无非就是那些形成腔的原子发出的电磁场。在这项工作中，这些场是在非相对论的经典域中计算出来的，目的是为了分析低频范围内腔体内辐射的分布。在空腔为球形的假设下，获得了黑体辐射在一定频率下的强度，并发现该强度仅在空腔中心附近的一小部分是均匀的。借助均分定理，黑体辐射的强度或光谱随腔温度的变化而表达，并满足熟悉的瑞利-吉恩斯定律。还讨论了黑体辐射的其他一些特性。