A black body radiates heat energy at the rate of 2 xx 10^(5)J//s m^(2) at the temperature of 127^(@)C. Temperature of the black body at which rate of heat radiation 32 xx 10^(5) J//s m^(2), is

A black body radiates heat energy at the rate of 2 xx 10^(5)J//s m^(2)

1.	A black body radiates heat energy at the rate of 2 xx 10^(5)J//s m^(2) at the temperature of 127^(@)C. Temperature of the black body at which rate of heat radiation 32 xx 10^(5) J//s m^(2), is
Answer» 400K 600K 800K 200K Solution :Here, `E_(1) = 2 xx 10^(5)J//s m^(2), T_(1) = 127^(@)C= 400K and E_(2) = 32 xx 10^(5) J//s m^(2)` By Stefan.s LAW, the rate of emission of radiated energy per unit area per unit time is `E= sigma T^(4)` `:. (E_(2))/(E_(1)) = (T_(2)^(4))/(T_(1)^(4)) or (T_(2))/(T_(1)) = ((E_(2))/(E_(1)))^(1//4) = ((32 xx 10^(5))/(2 xx 10^(5)))^(1//4) = 2` or `T_(2) = 2 xxT_(1) =2 xx 400= 800K`