Radiation heat transfer radiative transitions

Radiative heat transfer or thermal radiation is a distinctly separate mechanisms from conduction and convection for the transport of heat. Thermal radiation is associated with the rate at which energy is emitted by the material as a result of its finite temperature. The mechanism of emission is related to energy released as a result of oscillations or transitions of the many electrons that constitute the material. These oscillations are, in turn, supported by the internal energy for this reason the temperature drops. The emission of thermal radiation is thus associated with thermally excited conditions within the matter. 

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