a ray of light hits the boundary between two transparent materials, it is divided into a reflected and a refracted ray.

* The law of reflection says that the reflected ray lies in the plane of incidence, and the angle of reflection equals the angle of incidence.
* The law of refraction says that the refracted ray lies in the plane of incidence, and the sine of the angle of incidence divided by the sine of the angle of refraction is a constant: where is a constant for any two materials and a given wavelength of light. If the first