Question

Exitance is defined as the power per unit area that is emitted from the surface of an object. For a blackbody radiator, the exitance emitted is dependent upon its temperature. Calculate the exitance in W/cm2W/cm2 for a blackbody radiator at 74 K74 K and 323 K.323 K.

exitance at 74 K=exitance at 74 K=

W/cm2W/cm2

exitance at 323 K=

Answer 1

A Exotance is defined as the power per unit area that is emitted from the surface of an obiect. - For a blackbody radiator, the exitance emitted depends upon its temperature. 1. The total power radiated due to all frequencies per unit surface area live RLT) es Proportional to the fourth Power of the absolute temperature of the black body. R(T) = OTU (a) This is the stefan-Boltzman law. The constant of Proportionality & is called the stefan's constant and has the value T= 5.67x108 w mzah Now, exitance at T= 74K RETO = 774 = 5.67x 168 x (7434 Wasz = 5.67 x 16 °x (741)9 x toy Wlema = 0.012 x168 W/cm2

еҳқоса а4 Т- ЗА3 к. R(T) = = = 0T9 Wima 5.67x108x (323)" x 104 W/cm2 6.17 x 102 W/cm² .: is over most out on best come The exatance of the black body radiator at T = 74k 0.017x102 Wema and at T = 393k is 6.178 10 2 W/m². Cans)