Determine the amount of heat radiated per second by a body having a surface area of 12 cm ^2 , which is maintained in thermal equilibrium inside a room at a temperature of 20^ C . The surface emissivity is 0.80 and = 6.0 10⁻⁸ W m ⁻² K ⁻⁴ .

Step-by-step solution

The temperature of the body in thermal equilibrium with the room is T = 20^ C = 293 K . The surface area of the body is A = 12 cm ^2 = 12 10⁻⁴ m ^2 . According to the Stefan-Boltzmann law, the amount of heat radiated per second by the body is given by: P = e A T^4 Substituting the given values: P = 0.80 (6.0 10⁻⁸) (12 10⁻⁴) (293)^4 P = 57.6 10⁻¹² 7.37 10^9 P 0.4245 W Rounding off, the heat radiated per second is 0.42 W .