Definition of Snell's law in English:

Snell's law


  • A law stating that the ratio of the sines of the angles of incidence and refraction of a wave are constant when it passes between two given media.

    • ‘This was developed with ray diagrams and key formulae such as Snell's law and the lens equation.’
    • ‘Fermat proposed that light follows the path which takes the shortest time, enabling Snell's law of refraction to be deduced mathematically.’
    • ‘One might imagine that an experimental determination of Snell's law would be a simple matter.’
    • ‘In bi-directional transmission distribution functions it is also necessary to include refraction, which is described by Snell's law.’
    • ‘The largest angle allowed in the photoresist film is inversely related to its refractive index, as calculated using Snell's law and assuming a 90° half angle in air.’


Late 19th century: named after Willebrord van Roijen Snell (1591–1626), Dutch mathematician.


Snell's law