Snell Theory

Snell's Law

Snell's law (also called Snell-Descartes law) is a formula used to calculate the refractive angle of light by traversing the separation surface between two means of propagating light (or any electromagnetic wave) with a refractive index. different. The name comes from its discoverer, the Dutch mathematician Willebrord Snel van Royen (1580-1626). They called it "Snell" because of their surname, but they put two "l" for their name Willebrord which carries two "l".

It affirms that the multiplication of the refractive index by the sine of the angle of incidence with respect to the normal is constant for any ray of light incident on the separating surface of two media. That is, the component of the refractive index parallel to the surface is constant. Although Snell's law was formulated to explain the phenomena of refraction of light, it can be applied to all types of waves crossing a separation surface between two media in which the speed of propagation of the wave varies.

Snell's law can be derived from the Fermat principle, which indicates that the path of light is one in which light rays need less time to go from one point to another. In a classic analogy proposed by physicist Richard Feynman, the area of ​​a lower refractive index is replaced by a beach, the area of ​​a higher refractive index by the sea, and the fastest way for a lifeguard on the beach to rescue a person who drowns in the sea is to travel his way to it through a path that verifies Snell's law, ie, traveling more space through the medium faster and less in the slower half turning its path at the intersection between the two.

References
Snell's Law. (2018). Retrieved from https://en.wikipedia.org/wiki/Ley_of_Snell

Reflection and Refraction of Light | Fisicalab. (2018). Retrieved from https://www.fisicalab.com/apartado/reflexion-refraccion-luz#contents

Reflection and Refraction of Light | Fisicalab. (2018). Retrieved from https://www.fisicalab.com/apartado/reflexion-refraccion-luz#contents