Question

Explain Stefan's law of Radiation?

Answer 1

Explanation:

Stefan-Boltzmann law, statement that the total radiant heat power emitted from a surface is proportional to the fourth power of its absolute temperature. The law applies only to blackbodies, theoretical surfaces that absorb all incident heat radiation.

Answer 2

Stefan's law :- Stefan's law states that the emissive power of a black body is directly proportional to the fourth power of its absolute temperature.

$\boxed{ \boxed{ \sf \purple{i.e, \: E \propto {T}^{4}}}}$

$\sf{i) \: for \: a \: black \: body \: - - > \: i.e, E = \sigma {T}^{4}} \: \:( where \: \sigma \: = stefan's \: law )$

$\sf{ii) \: for \: any \: body \: - - > \: i.e, E = e \sigma {T}^{4}} \: \:( where \: e \: i s \: emissivity)$

$\boxed{ \boxed{ \sf \sigma \: = \: stefan's \: constant \: = 5.67 \times {10}^{ - 8} W \: {m}^{ - 2} \: K ^{ - 4} }}$

$\sf{It \: depends \: on \: the \: nature \: of \: surface \: of \: the \: body. }$

$\sf{Its \: value \: ranges \: from \: 0 \: to \: 1}$

$\sf \purple{For \: a \: black \: body, } \sf{e=1 \: and \: for \: a \: perfect \: reflector, \: e=0}$

$\boxed{ \boxed{Emissive \: power \: (E) = \frac{radiating \: power \: (P)}{surface \: area \: of \: the \: body \: (A)}}}$

$\sf{E = \frac{P}{A} \implies \frac{P}{A} = e \sigma {T}^{4}}$

$\boxed{ \boxed{ \sf{Radiating \: power \: (P) = e \sigma A {T}^{4}}}}$