A black body is at 727° C. It emits energy at a rate which is proportional to

Question

A black body is at 727° C. It emits energy at a rate which is proportional to (A) (727)2 (B) (1000)4 (C) (1000)2 (D) (727)4

Tardigrade Admin · Accepted Answer

Amount of heat energy radiated per second by unit area of a black body is directly proportional to fourth power of absolute temperature.
According to Stefan's law,

E \propto T^{4}

or

E = σ T^{4}

where

σ

is constant of proportionality and called Stefan's constant. Its value is

5.67 \times 1 0^{- 8} W m^{- 2} K^{- 4}

Hence

E \propto (727 + 273)^{4}

E =\propto (1000)^{4}

Q. A black body is at $72 7^{\circ} C$ . It emits energy at a rate which is proportional to

$(727)^{2}$

$(1000)^{4}$

$(1000)^{2}$

$(727)^{4}$

Q. A black body is at 727∘C. It emits energy at a rate which is proportional to

(727)2

(1000)4

(1000)2

(727)4

Q. A black body is at $72 7^{\circ} C$ . It emits energy at a rate which is proportional to

$(727)^{2}$

$(1000)^{4}$

$(1000)^{2}$

$(727)^{4}$