Question

Two spheres of the same material have radii 1 m and 4 m and termperatures 4000 K and 2000 K respectively. The ratio of energy radiated per second by the first sphere to that by the second is : 

(a) 1 : 1 

(b) 16 : 1 

(c) 4 : 1 

(d) 1 : 9

Answer 1

Correct option  (a) 1 : 1   

Explanation:

Energy radiated per second by a body which has surface area A at temperature T given by Stefan's law is