Editing Refraction (section)

{{Short description|Physical phenomenon relating to the direction of waves}}
{{For|heat tolerant metals and ceramics|Refractory metals|Refractory}}
{{For|the Runaways episode|Refraction (Runaways)}}
{{Distinguish|text=[[Diffraction]], the change in direction of a wave around an obstacle}}
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[[File:Refraction photo.png|thumb|A ray of light being refracted in a plastic block]]
In [[physics]], '''refraction''' is the redirection of a [[wave]] as it passes from one [[transmission medium|medium]] to another. The redirection can be caused by the wave's change in speed or by a change in the medium.<ref>{{cite web |url=https://www.britannica.com/science/refraction |title=Refraction  |author=((The Editors of Encyclopaedia Britannica)) |website=Encyclopaedia Britannica |access-date=2018-10-16}}</ref> Refraction of [[light]] is the most commonly observed phenomenon, but other waves such as [[sound wave]]s and [[Wind wave|water waves]] also experience refraction. How much a wave is refracted is determined by the change in wave speed and the initial direction of wave propagation relative to the direction of change in speed.

Optical [[Prism (optics)|prism]]s and [[Lens (optics)|lenses]] use refraction to redirect light, as does the [[human eye]]. The refractive index of materials varies with the [[wavelength]] of light,<ref name=dispersion_ELPT>R. Paschotta, article on [https://www.rp-photonics.com/chromatic_dispersion.html chromatic dispersion] {{webarchive|url=https://web.archive.org/web/20150629012047/http://www.rp-photonics.com/chromatic_dispersion.html |date=2015-06-29 }} in the [https://www.rp-photonics.com/encyclopedia.html Encyclopedia of Laser Physics and Technology] {{webarchive|url=https://web.archive.org/web/20150813044135/http://www.rp-photonics.com/encyclopedia.html |date=2015-08-13 }}, accessed on 2014-09-08</ref> and thus the angle of the refraction also varies correspondingly. This is called [[dispersion (optics)|dispersion]] and causes [[prism (optics)|prisms]] and [[rainbow]]s to divide white light into its constituent spectral [[color]]s.<ref name=hyperphysics_dispersion>Carl R. Nave, page on [http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/dispersion.html Dispersion] {{webarchive|url=https://web.archive.org/web/20140924222742/http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/dispersion.html |date=2014-09-24 }} in [http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html HyperPhysics] {{webarchive|url=https://web.archive.org/web/20071028155517/http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html |date=2007-10-28 }}, Department of Physics and Astronomy, Georgia State University, accessed on 2014-09-08</ref>