Stefan's law

Ayushi

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?

Kurdt

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

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?

rock.freak667

It would still radiate heat, it is just that it would have a net heat gain.

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?

rock.freak667

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".