Two spheres ' S ₁ ' and ' S ₂ ' have same radii but temperatures are ' T ₁ ' and ' T ₂ ' respectively. Their emissive power is same and emissivity is in the ratio 1: 4 . Then the ratio ' T ₁ ' to ' T ₂ ' is

Step-by-step solution

The correct option is (D). Concept: Emissivity(e) = ( rate of radiation emitted thourgh a unit area of material) (rate of radiation emitted through a unit area of blackbody) Stefan-Boltzmann law states that the amount of radiation emitted by a black body per unit area is directly proportional to the fourth power of the temperature T . = T ^4 , where is the Stefan coefficient. Therefore, ₁= e ₁ T ₁^4 and ₂= e ₂ T ₂^4 . It is given that emmisive power of the both spheres of equal radius is the same. So, e ₁ T ₁^4= e