Question

29.
Two metal spheres of same material have diameter
in the ratio of 1:2. The ratio of their rates of
cooling is
(1) 4:1
(2) 2:1
(3) 1:2
(4) 1:4​

Answer 1

Answer:

 Radiation is directly proportinal to area of the surface so cooling  rate also will be dirctly proportional to the surface area hence ratio of cooling rate of these =r12/r22=1/4=1:4