A mathematical relationship describing the extent to which light is refracted by a medium.
The index of refraction of the medium and the angle of incidence of the incoming light ray determine the angle of refraction.
The law was apparently discovered in 1621 by Dutch mathematician Willebrord van Roijen Snell (either 1580 or 1591-1626), but it was first published by French mathematician and philosopher René Descartes (1596-1650) under the name Law of Sines in his 1637 work La Dioptrique. It seems probable that Descartes did not develop his Law of Sines independently and in fact learned of it from reading Snells work, and so whether this law is called Snells Law or Descartes Law of Sines really depends on whether or not you are French.
cf. angle of incidence, refraction, refractive index.
Entry last updated 2002-05-09. Term 1130 of 1487.
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