The total energy radiated by a perfectly black body depends only on its temperature. Stefan formulated a relation between total heat radiation and temperature which is known as Stefan's law.
It states that the total energy radiated per second per unit area by the surface of perfectly black body is directly proportional to the fourth power of its absolute temperature. If E be the total energy emitted per second per unit area by a black body. T be the absolute temperature of surface of the body. According to the statement of Stefan's law, E directly depends on T^4 or, Ε = σΤ^4 where, σ is universal constant known as Stefan's constant. Value of o is 5.672 x 10-8 Wm-2K-4.
If the body is not perfectly black, its emissivity is e, then
Ε =eσΤ^4
Now, suppose the black body at absolute temperature T is kept in an enclosure (or surrounded by another black body) at absolute temperature Ts, then the black body radiates as well as absorbs heat.
Here, heat lost (or radiated) by black body =σ T^4
heat absorbed by the black body = σTs^4 Hence, net heat radiated per second per unit area is,
R = σT^4 - σTs^4 = σ(Τ^4 -Ts^4)
This is known as Stefan-Blotzmann law. The above relation is true only for perfectly black body but a perfectly black body in practice is not available. So, the relation of a body which is not perfectly black is,
R = eσ (T^4-Ts^4)
Links:
Emissivity:
• emissivity Class11(Nep...
👉state stefan boltzmann law
👉derivation of stefan boltzmann law from planck's radiation law
👉state and prove stefan boltzmann law
👉explain stefan boltzmann law
👉verification of stefan-boltzmann law experiment
👉 stefan boltzmann law of blackbody radiation
👉 stefan's boltzmann law of radiation
👉 state and prove stefan boltzmann law of blackbody radiation
👉stefan boltzmann law
👉stefan boltzmann law class 11 physics
Hastages:
#emissivity#stefanslaw#stefanboltzmannlaw
Негізгі бет Stefan Boltzmann Law Class11||P-11||
Пікірлер