# What reason of light refraction

Light refraction can be observed in everyday life. For this purpose it is enough to lower a spoon in transparent glass with water. A part of a spoon which is in water will be visually a little displaced.

## Law of light refraction

This simple law is passed in a school course of physics. It the point is that light, passing from one environment into another, changes the direction. He acts for one and all environments.

One of fundamental laws of physics says that the speed of light is equal in a vacuum to 300000 km/s. What this speed in other substances? It will be a little less, but the order will remain same. In any environment light moves on the shortest rectilinear trajectory. If speed became less, then the beam, upon transition from one environment to another, will surely change the direction.

The law of refraction sounds so: the relation of a sine of the angle of falling to a sine of the angle of refraction is a constant for two certain environments. This size is called relative index of refraction (or the index of refraction of the second Wednesday concerning the first). The falling, reflected beam and also the perpendicular restored in a falling point lie in one plane. Hades and refractions can be equal if light falls on limit of the section at right angle. In other cases they differ. The hade will be more angle of refraction if light passes from less dense environment into more dense. An absolute measure of refraction is called the relation of the speed of light in a vacuum to the speed of light in this environment. Wednesday which has this indicator less is considered less dense. Air has the smallest optical density close to vacuum density.

## Double refraction

If the ray of light gets on a certain Wednesday, it can experience double refraction. The similar environment are two crystals of the Irish spar having an appearance of a triangular prism with a right angle. They are stuck together on a hypotenuse by means of the Canadian balm. A beam, getting on such Wednesday, it is divided into two beams which are called ordinary and unusual. Double refraction is explained by heterogeneity (anisotropism of the environment). It is all about dielectric permeability of a crystal which values can differ depending on the direction. Other phenomenon - light polarization is the cornerstone of double refraction. The unusual beam is polarized, that is fluctuations of a light vector (vector of electric field), will be focused in strictly certain direction. The ordinary beam is not polarized and usually directed along an optical axis of a crystal.

Author: «MirrorInfo» Dream Team