Stefan's law

by Ayushi
Tags: stefan
 P: n/a Hello i am a new member of this forum. I am a student of class 11th. I came across a new law , 'Stefan's law', in my class. I did not understand it much. Could any of you help me to understand it please?
 Emeritus Sci Advisor PF Gold P: 4,980 It just states that the energy radiated per unit area per unit time by a black body is proportional to the absolute temperature raised to the fourth power. http://hyperphysics.phy-astr.gsu.edu...mo/stefan.html
 P: 29 What if it is surrounded by something of a temperature higher than itself? Would it still radiate energy? Won't that be against thermodynamic laws?
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P: 6,202
Stefan's law

 Quote by asdofindia What if it is surrounded by something of a temperature higher than itself? Would it still radiate energy? Won't that be against thermodynamic laws?
It would still radiate heat, it is just that it would have a net heat gain.
 P: 121 Why does on Stefan's law only the emissivity of the object is used- why the emissivity of the surrounding is not taken into account?
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P: 6,202
 Quote by GT1 Why does on Stefan's law only the emissivity of the object is used- why the emissivity of the surrounding is not taken into account?
Because the object is radiating heat to the surroundings. So if the object it white, it will radiate less heat than if it were black.

How much radiation reaches another object depends on something called "view factor".

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