Register to reply

Stefan's law

by Ayushi
Tags: stefan
Share this thread:
Ayushi
#1
Jul3-08, 12:12 PM
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?
Phys.Org News Partner Physics news on Phys.org
Step lightly: All-optical transistor triggered by single photon promises advances in quantum applications
The unifying framework of symmetry reveals properties of a broad range of physical systems
What time is it in the universe?
Kurdt
#2
Jul3-08, 12:52 PM
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
asdofindia
#3
Mar31-11, 08:35 AM
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?

rock.freak667
#4
Mar31-11, 10:26 AM
HW Helper
P: 6,202
Stefan's law

Quote Quote by asdofindia View Post
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.
GT1
#5
Apr2-11, 06:14 AM
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?
rock.freak667
#6
Apr2-11, 01:33 PM
HW Helper
P: 6,202
Quote Quote by GT1 View Post
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".


Register to reply

Related Discussions
What is stefan's constant? Astronomy & Astrophysics 1
Stefan's law Understanding Classical Physics 3
Stefan's Law And Definition Of Temperature Classical Physics 1
Newton's Law of Cooling and Stefan's Law Advanced Physics Homework 0
Newton's Law of Cooling and Stefan's Law General Physics 10