Changes

[[File:lighterstill.jpg]][[File:1_Atomic_Radiation.jpg|right|frame]]

[[File:lighterstill.jpg]][[File:1_Atomic_Radiation.jpg|right|frame]]

*Date: [http://www.wikipedia.org/wiki/15th_Century 15th century]

*Date: [https://www.wikipedia.org/wiki/15th_Century 15th century]

==Definitions==

==Definitions==

*1 a : the [[action]] or [[process]] of radiating  

*1 a : the [[action]] or [[process]] of radiating  

*3 : radial arrangement

*3 : radial arrangement

==Description==

==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]

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]] [https://en.wikipedia.org/wiki/Ionizing_radiation ionizing radiation] (e.g., as occurring in nuclear weapons, nuclear reactors, and [https://en.wikipedia.org/wiki/Radioactive_decay radioactive] substances), but it can also refer to [[electromagnetic]] radiation (i.e., [https://en.wikipedia.org/wiki/Radio_waves radio waves], [https://en.wikipedia.org/wiki/Infrared infrared light], [https://en.wikipedia.org/wiki/Light visible light], [https://en.wikipedia.org/wiki/Ultraviolet ultraviolet light], and [[X-ray]]s) which can also be ionizing radiation, to [https://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.[https://en.wikipedia.org/wiki/Radiation]

[[Category: Physics]]

[[Category: Physics]]