Refraction, originating from the Latin word refractio , is the action and consequence of refracting. This verb refers to making a certain radiation change its direction by passing obliquely from one medium to another with different propagation speed.
Refraction, therefore, is a modification of the direction of a wave when it passes from one medium to another. For this change to occur, the wave must strike obliquely on the surface that separates the two media and these must have different refractive indices.
The term refraction is often confused with reflection, which is why it is necessary to define the latter slightly: it is the rebound that a ray experiences when striking a smooth and polished surface and returning to the previous medium. In this case it is true that: the normal and the incident ray form an angle equal to the one that the normal forms with the reflected ray; the normal, the incident ray and the reflected ray are in the same plane.
It is known as refractive index to the existing ratio of the velocities of wave propagation in vacuum and in medium X. The change in direction, on the other hand, can be explained through the so-called Snell's law which, in turn, derives from Fermat's principle.
The principle of Fermat, meanwhile, belongs to the field of optics (the branch of physics that believes that light is a wave, thanks to which explains certain phenomena that could not, if taken as lightning), and proposes the following: the path that light travels when it propagates between two points is such that it could not be done in less time.
The Snell 's law (also known as Snell 's law-Descartes ) is a formula used to calculate the angle of refraction of light when it passes through the surface separating two propagation media (either light or any electromagnetic wave), which must have different refractive indices. It should be noted that the name of the mathematician behind this discovery is Willebrord Snel van Royen, and that the double 'l' arose as a combination of Snel and Wi ll ebrord .
Another statement present in Snell's law is that the result of multiplying the sine of the angle of incidence by the index of refraction is constant for all light rays that strike the surface that separates two media.
The most common example of refraction is the phenomenon that occurs when a wooden rod or stick is inserted into a glass filled with water. Due to the refraction of light, an optical effect is generated that makes the rod appear broken.
It is important to note that refraction is a phenomenon that can be seen in any wave, beyond light. The waves that are generated by an earthquake and radio waves are also susceptible to refraction.
The atmospheric refraction finally makes the stars look over the actual position as observed is modified by the phenomenon of refraction produced by the atmosphere.