A hollow sphere and a solid sphere of the same material and equal radii are heated to the same temperature. In this case,
A)The cooling rate will be the same for the two spheres and hence the two spheres will have equal temperatures at any instant
B)Both the spheres will emit equal amount of radiation per unit time in the beginning
C)Both will absorb equal amount of radiation from the surrounding in the beginning
D)Both (B) & (C)

Question

Quizplus · Accepted Answer

The rate of emission and absorption of radiation for objects depends on their surface area and not on whether they are solid or hollow. Since both spheres have the same material and equal radii, they have the same surface area, leading to equal emission and absorption of radiation per unit time initially.

A Hollow Sphere and a Solid Sphere of the Same