Two spheres,both at the same temperature,have radii R and 2R.How do the energies radiated per unit area compare for these spheres?
A) They are the same.
B) The larger sphere has twice the value of the smaller sphere.
C) The larger sphere has 4 times the value of the smaller sphere.
D) The larger sphere has 16 times the value of the smaller sphere.

Question

Quizplus · Accepted Answer

The energy radiated per unit area by a black body is given by the Stefan-Boltzmann law, which depends only on the temperature and not on the size of the sphere. Since both spheres are at the same temperature, the energy radiated per unit area is the same for both.

Two Spheres,both at the Same Temperature,have Radii R and 2R