Radiation
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Reverted edits by [[Special:Contributions/91.106.188.147|91.106.188.147]] (using [[WP:HG|Huggle]])
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'''Radiation''', as used in [[physics]], is [[energy]] in the form of [[waves]] or moving [[subatomic particles]] emitted by an atom or other body as it changes from a higher energy state to a lower energy state. Radiation can be classified as ''[[ionizing radiation|ionizing]]'' or ''[[non-ionizing radiation]]'', depending on its effect on atomic [[matter]]. The most common use of the word "radiation" refers to ionizing radiation. Ionizing radiation has enough energy to ionize atoms or molecules while non-ionizing radiation does not. ''[[Radioactive material]]'' is a physical material that emits ionizing radiation.
[[Image:RadiationPenetration2-pn.png|300px|thumb|right|This shows three different types of radiation and their penetration levels]]
==Types of Radiation==
There are three principal types of ionizing radiation: [[Alpha decay|alpha]], [[Beta decay|beta]] and [[Gamma ray|gamma]] radiation. They are all emitted from the nucleus of an unstable atom. Less commonly encountered are spontaneous [[nuclear fission]]; [[positron emission]], which is utilized in [[positron emission tomography]]; and [[neutron emission]]. [[Electron capture]] results in the spontaneous emission of an X-ray. Certain isotopes of [[radium]] have a decay mode where they emit an entire [[Carbon-12|<sup>12</sup>C<sub>6</sub>]] nucleus.
==Discovery==
[[Wilhelm Röntgen]] is credited with the discovery of [[X-Rays]]. [[Henri Becquerel]] found that [[uranium]] salts caused fogging of an unexposed photographic plate, and [[Marie Curie]] discovered that only certain elements gave off these rays of energy. He named this behaviour [[radioactivity]].
In December of 1898, Marie Curie and [[Pierre Curie]] discovered radium in pitchblende. This new element was two million times more radioactive than uranium, as described by Marie.
== See also ==
<div style="-moz-column-count:2; column-count:2;">
* [[Ionizing radiation]]
* [[Non-ionizing radiation]]
* [[Background radiation]], which actually refers to the background ionizing radiation
* [[Black hole]]
* [[Cosmic microwave background radiation]], 3[[kelvin|K]] [[blackbody radiation]] that fills the [[Universe]]
* [[Radiant energy]], radiation by a source into the surrounding environment.
* [[Radiation damage]] - adverse effects on materials and devices
* [[Radiation hormesis]] - dosage threshold damage theory
* [[Radiation poisoning]] - adverse effects on life forms
* [[Radiation hardening]] - making devices resistant to failure in high radiation environments
* [[Radioactive contamination]]
* [[Radioactive decay]]
* [[Hawking radiation]]
* [[Cherenkov radiation]]
* [[Cyclotron radiation]]
* [[Solar radiation]]
* [[Synchrotron radiation]]
* [[Radiation reaction]]
</div>
[[Category:Radiation| ]]
[[Category:Physics]]
[[Category:Fundamental physics concepts]]
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