Refraction of light. Collapse of the electromagnetic wave.
The light is called the part of the entire spectrum of electromagnetic waves propagating in space of electrical and magnetic field disturbances. Wave spectrum of electromagnetic range extends from radio waves for gamma radiation that is picked up by human eyes, from about 400 nm to 750 nm ( Newton metre ). The speed of light in a vacuum is the same for all wavelengths and is approximately 300,000 km / s.
In each material centre the speed of light is less than in a vacuum. In addition, in a specific material center depends on the wavelength - the higher the wavelength, the higher the speed.
Light is not just an electromagnetic wave. It is also a stream of particles called photons.
Assumptions of geometric optics says that in homogeneous, not distracting and transparent centers electromagnetic waves propagate in straight lines. The behavior of a beam of light at the boundary of two centers will be both reflected from the surface dividing both centers, as well as the refracted at going to the second center.
Let's start with the light reflection.
As I wrote above, the reflection law say that the light (wave) falling on the border of two centers is reflected, while remaining in the center in which it spreads.
The angle of reflection equals the angle of incidence where the angles of incidence and reflection lie in one plane. So as shown in the graphic above, the angle θi will be equal to angle θr. It is worth to pay attention to the fact that both the angle of incidence and the reflection are counted from the Normal, and not from the surface delimiting the centers.
A typical, most-known reflection occurs when the second medium is not at all permeable to light. If in addition in this second medium the light is not absorbed, the whole beam is reflected. In this way, we get a mirror. Objects with an uneven surface on which a parallel beam of light falls are scattering light in all directions.
Speaking about the phenomenon of light refraction, we can state that changing the direction of the light rays during the collapse is not accidental. This describes the law of refraction of light, sometimes called Snellius' law.
In short if light goes from one centre to the other, for example from air to water, it refracts at the border of centers. Along with the change of the center, the direction of light usually changes.
The law of refraction of light combines two angles - the angle of incidence on the surface delimiting two centers and the angle of refraction arising when the radius passes the boundary and starts to propagate in the second center.
The presentation of this dependence can be described mathematically, where:
α - angle of incidence.
β - the angle of refraction.
v1 -speed of light propagation in the center I.
v2 - speed of light propagation in the center II.
n1 - absolute refractive index of the center I.
n2 - absolute refractive index of the center II.
One of the main factors that differ the total reflection of the light from its refraction is the optical density of the material on which it interacts. If the density of the center in which the light falls is greater than where it falls, the angle of break is greater and vice versa.
The refraction of light causes a number of interesting effects - including the illusion of "breaking" a teaspoon of tea placed in a glass, an incorrect location of the lake bottom when we look at it from the shore. The refraction of light is used to build lenses used in spectacles, camera lenses, telescopes and other optical devices.
Examples of Refraction of light, among others when the light passes:
This phenomenon can also be found in various cultural references. The image, which shows a beam of white light striking a triangular prism and separating into components (rainbow), was placed on the studio album "Dark Side of the Moon" from the 1973 by British group Pink Floyd, which was clearly inspired by this phenomenon.
Source:
It is worth associating a refraction of light with the change of the center quite closely, because there is a similar optical phenomenon - deflection. Deflection has a different nature (occurs in one center) and runs differently, so confusing these phenomena would be a serious mistake.
References:
[1] http://fizyka.ur.krakow.pl/cwicz41.pdf
[2] http://www.fizykon.org/optyka/optyka_geometryczna_prawo_zalamania_swiatla.htm
[3] http://wh.agh.edu.pl/wp-content/uploads/2018/06/Met-Fiz-2.-1-Zjawiska-optyczne-plansze.pdf
[4] https://www.physicsclassroom.com/class/waves/Lesson-3/Reflection,-Refraction,-and-Diffraction
