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Jump to navigationJump to searchCreated page with 'File:lighterstill.jpgright|frame ==Etymology== Latin opacus *Date: [http://www.wikipedia.org/wiki/17th_Century 1641] ==Definitions== *1 : exhi...'
[[File:lighterstill.jpg]][[File:Riedel.opaque.jpg|right|frame]]
==Etymology==
[[Latin]] opacus
*Date: [http://www.wikipedia.org/wiki/17th_Century 1641]
==Definitions==
*1 : exhibiting opacity : blocking the passage of radiant [[energy]] and especially [[light]]
*2 a : hard to [[understand]] or explain <opaque prose>
:b : obtuse, thickheaded
==Description==
'''Opacity''' is the [[measure]] of impenetrability to [http://en.wikipedia.org/wiki/Electromagnetic_radiation electromagnetic] or other kinds of [http://en.wikipedia.org/wiki/Radiation radiation], especially visible [[light]]. In radiative transfer, it describes the absorption and scattering of radiation in a [[medium]], such as a [[plasma]], dielectric, shielding [[material]], glass, etc. An opaque object is neither [[transparent]] (allowing all light to pass through) nor [[translucent]] (allowing some light to pass through). When light strikes an [[interface]] between two substances, in general some may be [[reflected]], some absorbed, some scattered, and the rest [[transmitted]] (also see [[refraction]]). [[Reflection]] can be diffuse, for example light reflecting off a white wall, or specular, for example light reflecting off a [[mirror]]. An opaque substance transmits very little light, and therefore reflects, scatters, or absorbs most of it. Both mirrors and carbon black are opaque. Opacity depends on the [[frequency]] of the light being considered. For instance, some kinds of glass, while [[transparent]] in the visual range, are largely opaque to [http://en.wikipedia.org/wiki/Ultraviolet ultraviolet light]. More extreme frequency-dependence is visible in the [http://en.wikipedia.org/wiki/Absorption_line absorption lines] of cold gases. Opacity can be quantified in many ways; for example, see the article [http://en.wikipedia.org/wiki/Mathematical_descriptions_of_opacity mathematical descriptions of opacity].[http://en.wikipedia.org/wiki/Opacity_%28optics%29]
[[Category: Physics]]
==Etymology==
[[Latin]] opacus
*Date: [http://www.wikipedia.org/wiki/17th_Century 1641]
==Definitions==
*1 : exhibiting opacity : blocking the passage of radiant [[energy]] and especially [[light]]
*2 a : hard to [[understand]] or explain <opaque prose>
:b : obtuse, thickheaded
==Description==
'''Opacity''' is the [[measure]] of impenetrability to [http://en.wikipedia.org/wiki/Electromagnetic_radiation electromagnetic] or other kinds of [http://en.wikipedia.org/wiki/Radiation radiation], especially visible [[light]]. In radiative transfer, it describes the absorption and scattering of radiation in a [[medium]], such as a [[plasma]], dielectric, shielding [[material]], glass, etc. An opaque object is neither [[transparent]] (allowing all light to pass through) nor [[translucent]] (allowing some light to pass through). When light strikes an [[interface]] between two substances, in general some may be [[reflected]], some absorbed, some scattered, and the rest [[transmitted]] (also see [[refraction]]). [[Reflection]] can be diffuse, for example light reflecting off a white wall, or specular, for example light reflecting off a [[mirror]]. An opaque substance transmits very little light, and therefore reflects, scatters, or absorbs most of it. Both mirrors and carbon black are opaque. Opacity depends on the [[frequency]] of the light being considered. For instance, some kinds of glass, while [[transparent]] in the visual range, are largely opaque to [http://en.wikipedia.org/wiki/Ultraviolet ultraviolet light]. More extreme frequency-dependence is visible in the [http://en.wikipedia.org/wiki/Absorption_line absorption lines] of cold gases. Opacity can be quantified in many ways; for example, see the article [http://en.wikipedia.org/wiki/Mathematical_descriptions_of_opacity mathematical descriptions of opacity].[http://en.wikipedia.org/wiki/Opacity_%28optics%29]
[[Category: Physics]]
