Thermodynamics

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

  1. 1:1
  2. 1:9
  3. 16:1
  4. 4:1

Answer

Energy radiated per second by a body at a temperature T is given by stefen's law

E= σAT2

Use this formula for both and find the ratio which would come out to be 1:1.

The correct option is A.