State and prove Stefan-Boltzmann law.

1.	State and prove Stefan-Boltzmann law.
Answer» It states that the power (E) emitted per unit area by a body at absolute temperature,T is given by E = εσT⁴ Where E = Energy being emitted per second per unit area of surface ε = Emissivity or emissive power of that body (which is equal to 1 for black body) σ = Stefan’s constant = 5.67 × 10^-8 Jm^-2 K^-4 s^-1. If temperature of the surrounding is to be taken into consideration then the net rate of loss of energy as heat per unit area per second is given by E = εσ(T⁴ – T₀⁴ ) If the total area of surface is A, then the total energy radiated in t time E = Aεσt(T⁴ – T₀⁴ )

Answer»

It states that the power (E) emitted per unit area by a body at absolute temperature,T is given by E = εσT⁴

Where

E = Energy being emitted per second per unit area of surface

ε = Emissivity or emissive power of that body (which is equal to 1 for black body)

σ = Stefan’s constant = 5.67 × 10^-8 Jm^-2 K^-4 s^-1.

If temperature of the surrounding is to be taken into consideration then the net rate of loss of energy as heat per unit area per second is given by

E = εσ(T⁴ – T₀⁴ )

If the total area of surface is A, then the total energy radiated in t time

E = Aεσt(T⁴ – T₀⁴ )

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