Question

A metal sphere has a diameter of 4 cm and an emissivity of 0.35.Find out the energy lost by radiation in one second

Answer 1

use the Stefan's Law,

P = e(stefan's constant)A*T^4

where, P--- power, e = 0.35, stefan's constant = 5.67 * 10^-8, A = pi(0.04)^2 = 0.05, T(viz not given, so assumed) = 273K

=> P = 5.5115 J/s

hope, this rocks...