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1,875 bytes added ,  22:35, 20 May 2010
Created page with 'File:lighterstill.jpgright|frame *Date: [http://www.wikipedia.org/wiki/15th_Century 15th century] ==Definitions== *1 a : the action or [[...'
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*Date: [http://www.wikipedia.org/wiki/15th_Century 15th century]
==Definitions==
*1 a : the [[action]] or [[process]] of radiating
:b : the [[process]] of emitting radiant [[energy]] in the [[form]] of [[waves]] or [[particles]]
:c (1) : the combined [[processes]] of emission, transmission, and absorption of radiant [[energy]] (2) : the [[transfer]] of [[heat]] by radiation — compare conduction, convection
*2 a : something that is radiated
:b : [[energy]] radiated in the [[form]] of [[waves]] or [[particles]]
*3 : radial arrangement
==Description==
In [[physics]], '''radiation''' describes any [[process]] in which [[energy]] [[travel]]s through a [[medium]] or through [[space]], ultimately to be absorbed by another [[body]]. Non-physicists often [[associate]] the [[word]] [http://en.wikipedia.org/wiki/Ionizing_radiation ionizing radiation] (e.g., as occurring in nuclear weapons, nuclear reactors, and [http://en.wikipedia.org/wiki/Radioactive_decay radioactive] substances), but it can also refer to [[electromagnetic]] radiation (i.e., [http://en.wikipedia.org/wiki/Radio_waves radio waves], [http://en.wikipedia.org/wiki/Infrared infrared light], [http://en.wikipedia.org/wiki/Light visible light], [http://en.wikipedia.org/wiki/Ultraviolet ultraviolet light], and [[X-ray]]s) which can also be ionizing radiation, to [http://en.wikipedia.org/wiki/Sound acoustic radiation], or to other more obscure [[processes]]. What makes it radiation is that the [[energy]] radiates (i.e., it [[travels]] outward in straight lines in all directions) from the [[source]]. This [[geometry]] naturally leads to a [[system]] of [[measurements]] and [[physical]] [[units]] that are [[equally]] [[applicable]] to all [[types]] of radiation.[http://en.wikipedia.org/wiki/Radiation]

[[Category: Physics]]