Blackbodies spectral power distribution

Figure 2.2. Spectral power distribution of blackbodies with color temperatures of 2854 K (source A) and 6500K (Pivovonski, 1963 Billmeyer and Saltzman, 1981).

Figure 7.3a represents the Planck distribution for blackbody spectral emissive power with E-i p / as a function of XT. The band fraction of emitted energy in the region from 0 to XT is equal to the shaded area, which is expressed as and shown in Figure 7.3b. About a quarter of the emitted energy is at wavelengths shorter than nd nearly 95% of the emitted energy is distributed between and The spectral distribution of solar radiation can be...

Figure 8.3 Spectral radiant power (per unit time per unit area) distribution of a blackbody at various temperatures. Note that the maximum intensity, even at 3500 K, is still in the infrared region of the spectrum. The displacement of the maximum of the radiant energy shifts linearly with absolute temperature (dotted lines) in accordance with Wein s displacement law.

For a blackbody, the spectral distribution of hemispherical emissive power (integrated over the hemispherical solid angle) follows Plank s law ... 

Measurements of the total emission from a small hole in a heated cavity showed thermal radiation to be proportional to the fourth power of the cavity temperature (Stefan, 1879) Boltzmaim (1884) derived this power law from thermodynamic considerations. Nine years later, Wien (1893) found that the product of the wavelength at the radiation maximum and the cavity temperature was the same for a wide range of temperatures he also proposed an exponential radiation law, which was in good agreement with available measurements at short wavelengths (Wien, 1896). Shortly thereafter, Lummer and Pringsheim (1897,1899) made fairly precise measurements of blackbody emission between 100 °C and 1300 °C. By the end of the nineteenth century an extensive set of experimental evidence was available on the spectral distribution and temperature dependence of blackbody radiation. 

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