What is refraction?

  • (noun): The amount by which a propagating wave is bent.
    Synonyms: deflection, deflexion
    See also — Additional definitions below


Refraction is the change in direction of a wave due to a change in its medium. It is essentially a surface phenomenon. The phenomenon is mainly in governance to the law of conservation of energy and momentum. Due to change of medium, the phase velocity of the wave is changed but its frequency remains constant. This is most commonly observed when a wave passes from one medium to another at any angle other than 90° or 0°. Refraction of light is the most commonly observed phenomenon, but any type of wave can refract when it interacts with a medium, for example when sound waves pass from one medium into another or when water waves move into water of a different depth. Refraction is described by Snell's law, which states that for a given pair of media and a wave with a single frequency, the ratio of the sines of the angle of incidence θ1 and angle of refraction θ2 is equivalent to the ratio of phase velocities (v1 / v2) in the two media, or equivalently, to the opposite ratio of the indices of refraction (n2 / n1):

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Some articles on refraction:

Refraction - Gallery
... Refraction in a Perspex (acrylic) block The straw appears to be broken, due to refraction of light as it emerges into the air Photograph of refraction of ...
Total External Reflection
... reflected from an interface between two media of different indices of refraction (see Snell's law) ... For visible light, water has an index of refraction of 1.33 and for air it is very close to 1 ... For vacuum the index of refraction is exactly 1 for all wavelengths ...
Mirage Of Astronomical Objects - Mirages Versus Refraction
... Mirages are distinguished from other refraction phenomena ... is that a mirage might only produce images vertically, not sideways, while a simple refraction might distort and bend the images in any way ... in both images displayed in this section was caused by refraction, but while the image on the left, which is a mirage, demonstrates only vertical, distortion, the ...
Automated Refraction System
... An automated refraction system is a group of ophthalmic devices used during an eye examination to aid in the determination of a person's refractive error and prescription for ... The standard components of an automated refraction system are an electronic and motor driven phoropter (auto-phoropter, auto-refractor head) used to present powered lenses in front ... Automated refraction systems currently on the market vary in features, level of automation, ease of use, training required and documentation ...
Mirage Of Astronomical Objects - See Also
... to cause a similarly duplicate image of galaxies Refraction Atmospheric refraction Novaya Zemlya effect Looming and similar refraction phenomena ...

More definitions of "refraction":

  • (noun): The change in direction of a propagating wave (light or sound) when passing from one medium to another.