IR, visible and UV components in the spectral distribution of blackbody radiation

Abstract

The spectral distribution of blackbody radiation is given by the Planck radiation law, and the Stefan-Boltzmann and Wien displacement laws give the total power and the maximum of the spectral distribution respectively. However, the contributions of each of the IR, visible and UV components to the total radiation is not found in literature, although qualitative inferences can be made from the graphs of spectral irradiance given by the Planck radiation law. This article presents the percentage mix of IR, visible and UV components to the total radiant power of a blackbody as a function of temperature. At low temperature the radiant power is nearly 100% IR and the contributions of UV and visible components are nearly zero. As the temperature increases, the percentage of the IR component decreases, and the UV and visible components increase. The percentage of the visible component has a maximum value of 47.5% at 7100 K. At very high temperatures UV contributes the largest fraction to the radiant power with smaller, non-zero fractions of IR and visible radiation. At certain temperatures two of the three components contribute equally to the radiant power. The analysis has important application in medical and biophysics for UV protection from high temperature systems.