Black-Body Radiative Functions in a Given Spectral Range

In almost all areas of physics and astrophysics related to the measurement of spectral and integral properties of the emitted systems, a small interval of the electromagnetic spectrum has the practical interest [1]. Therefore, extensive numbers of tables of the Planck functions, Planck integrals, and their fractional values have been constructed in the finite spectral ranges [1–12]. In this chapter, the analytical expressions for the thermal radiative functions and a number density of photons over an arbitrary spectral range are presented. Using these exact analytical expressions the values of these functions are calculated for various ranges of the electromagnetic spectrum at different temperatures. Their values are presented in Tables 6.1–6.3.