Q.

Two spherical bodies of same materials having radii 0.2 m and 0.8 m are placed in same atmosphere. The temperature of the smaller body is 800 K and temperature of bigger body is 400 K. If the energy radiated from the smaller body is E, the energy radiated from the bigger body is (assume, effect of the surrounding to be negligible)         [2025]

1

256 E

 

2

E

 

3

64 E

 

4

16 E

 


Ans.

(2)

dθdt=σeAT4  PAT4

         =PsmallerPlarger=(0.2)2×8004(0.8)2×4004=116×16=1

  Plarger=Psmaller

  Energy will be same.