Difference between revisions of "Template:Electromagnetism-stub"

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imported>Chjoaygame
(add note on Schwarzschild's concept of radiative equilibrium which is used by some writers)
imported>Chjoaygame
(delete stub of radiative equilibrium because main article is now in place)
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| image    = Solenoid.svg
 
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| subject  = [[electromagnetism]]-related
 
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| category  = Electromagnetism stubs
 
| tempsort  =
 
| name      = Template:Electromagnetism-stub
 
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<noinclude>
 
[[ca:Plantilla:Esborrany d'electromagnetisme]]
 
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== Radiative Equilibrium ==
 
 
The discovery of the nature of radiation of heat was gradual. An important early contribution was made by P. Prevost in 1791, writing in French. Prevost considered that what is nowadays called the [[photon gas]] or [[electromagnetic radiation]] was a fluid that he called "free heat". The present writer's translation of Prevost's 1791 definition is as follows:
 
 
Absolute equilibrium of free heat is the state of this fluid in a portion of space which receives as much of it as it lets escape.
 
Relative equilibrium of free heat is the state of this fluid in two portions of space which receive from each other equal quantities of heat, and which moreover are in absolute equilibrium, or experience precisely equal changes.
 
The heat of several portions of space at the same temperature, and next to one another, is at the same time in the two species of equilibrium.
 
 
Prevost's contribution was often referred to as Prevost's exchange principle.
 
 
== Schwarzschild's Confusing Concept of Predominant Equilibrium ==
 
 
K. Schwarzschild in 1906 confused the terminology by his introduction of the concept of predominant equilibrium. He considered a system in which convection and radiation both operated but radiation was so much more efficient than convection that convection could be, as an approximation, neglected, and radiation could be considered predominant. Milne in 1930 noted that this led to a "logically indefensible" definition, but still he accepted its use.
 
 
== References ==
 
 
* Prevost, P. (1791). Memoire sur l'equilibre du feu. ''Journal de Physique'' (Paris), vol 38 pp. 314-322.
 
* Schwarzschild, K. (1906). Ueber das Gleichgewicht der Sonnenatmosphaere. ''Nachrichten von der Koeniglichen Gessellschaft der Wissenschaften zu Goettingen. Math.-phys. Klasse 195: 41-53. Translation in ''Selected Papers on the Transfer of Radiation'', ed. D.H. Menzel, Dover, New York, 1966.
 
* Milne, E.A. (1930). Thermodynamics of the Stars. In ''Handbuch der Astrophysik'', 3 (1): 63-255. Reprinted in ''Selected Papers on the Transfer of Radiation'', ed. D.H. Menzel, Dover, New York, 1966.
 

Revision as of 12:08, 15 August 2009