Physical phenomenon relating to the direction of waves
For heat tolerant metals and ceramics, see Refractory metals and Refractory.
Not to be confused with Diffraction, the change in direction of a wave around an obstacle.
A ray of light being refracted in a plastic block
In physics, refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium.[1] Refraction of light is the most commonly observed phenomenon, but other waves such as sound waves and 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.
For light, refraction follows Snell's law, which states that, for a given pair of media, the ratio of the sines of the angle of incidence and angle of refraction is equal to the ratio of phase velocities in the two media, or equivalently, to the refractive indices of the two media:[2]
Refraction of light at the interface between two media of different refractive indices, with n2 > n1. Since the phase velocity is lower in the second medium (v2 < v1), the angle of refraction θ2 is less than the angle of incidence θ1; that is, the ray in the higher-index medium is closer to the normal.
Optical prisms and lenses use refraction to redirect light, as does the human eye. The refractive index of materials varies with the wavelength of light,[3] and thus the angle of the refraction also varies correspondingly. This is called dispersion and causes prisms and rainbows to divide white light into its constituent spectral colors.[4]
A pen partially submerged in a bowl of water appears bent due to refraction at the water surface.
^The Editors of Encyclopaedia Britannica. "Refraction". Encyclopaedia Britannica. Retrieved 2018-10-16.
^Born and Wolf (1959). Principles of Optics. New York, NY: Pergamon Press INC. p. 37.
^R. Paschotta, article on chromatic dispersion Archived 2015-06-29 at the Wayback Machine in the Encyclopedia of Laser Physics and Technology Archived 2015-08-13 at the Wayback Machine, accessed on 2014-09-08
^Carl R. Nave, page on Dispersion Archived 2014-09-24 at the Wayback Machine in HyperPhysics Archived 2007-10-28 at the Wayback Machine, Department of Physics and Astronomy, Georgia State University, accessed on 2014-09-08
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eyeglass prescription. A refraction procedure consists of two parts: objective and subjective. An objective refraction is a refraction obtained without receiving...
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is the index of refraction of air at the observer's height, and μ0 is the index of refraction of air at Earth's surface. The refraction must be found by...
an index measurement if precision is required. In general, an index of refraction is a complex number with both a real and imaginary part, where the latter...
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"objective refraction" the clinician typically shows the person lenses of progressively higher or weaker powers in a process known as subjective refraction. Cycloplegic...
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goal. Another rarely used refraction technique involves the use of a stenopaeic slit (a thin slit aperture) where the refraction is determined in specific...
the direction of the beam. This change of direction is known as refraction. The refractive quality of lenses is frequently used to manipulate light in order...
and is dependent on the temperature, the index of refraction, and the pressure. The molar refractivity is defined as A = 4 π 3 N A α , {\displaystyle A={\frac...
of refraction occurs when there is an interface between a uniform medium with index of refraction n1 and another medium with index of refraction n2....
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by the wave. Changes to the path can be separated into super and under refraction: It is very common to have temperature inversions forming near the ground...
measurement of an index of refraction (refractometry). The index of refraction is calculated from the observed refraction angle using Snell's law. For...
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