## law of refraction of light

This simple law are held in a school course of physics.Its essence is that the light passing from one medium to another, changing its direction.It applies to all media, without exception.

One of the fundamental laws of physics states that the speed of light is 300,000 km / s.What is the speed of other substances?It will be a little less, but the order will remain the same.In any environment light moves along the shortest straight path.If the rate becomes smaller, the beam, the transition from one medium to another, be sure to change its direction.

law of refraction is: the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant for two specific environments.This value is called a relative refractive index (or index of refraction of the second medium rel
ative to the first).The incident reflected ray and the perpendicular to the point of incidence reduced lie in one plane.

angles of incidence and refraction can be equal to, if the light is incident on the interface at a right angle.In other cases, they are different.The angle of incidence is greater than the angle of refraction when light passes from a less dense to a more dense medium.The absolute refractive index is the ratio of the speed of light in a vacuum to the speed of light in a given medium.Wednesday, for which this figure is less considered less dense.Air has the lowest optical density close to the density of the vacuum.

## birefringence

If a beam of light falls in a particular environment, it can test the birefringence.Such an environment is the two Irish crystal spar, having the form of a triangular prism with a right angle.They are glued on the hypotenuse using Canada balsam.Ray, it getting in an environment that is divided into two beams, which are called ordinary and extraordinary.

birefringence is due to heterogeneity (anisotropic medium).The whole point of the dielectric constant of the crystal, the value of which may vary depending on the destination.

At the heart of the birefringence is another phenomenon - the polarization of light.Unusual beam is polarized, that is, fluctuations of the light vector (electric field) will be oriented in a very specific direction.Average beam is not polarized and is usually directed along the optical axis of the crystal.