Calculate the amount of heat radiated per second by a body of surface area 12 cm2 kept in thermal equilibrium in a room at temperature 200 C. The emissivity of the surface = 0.80 and σ=6.0×10−8Wm−2K−4
A = 12cm2=12×10−8×104m2,
T = 200C=2930 K, e =0.8
σ=6×10−8W/m2−K4
q = AeST4
= 12×10−4×0.8×6×10−8×(293)4
= 0.4245 = 0.42