The speed of light in a given medium is two third of its speed in vacuum. Find the absolute refractive index of the medium, by what percent does the medium of light reduce on entering the medium?
Answers
In optics, the refractive index or index of refraction of a material is a dimensionless number that describes how fast light propagates through the material. It is defined as
{\displaystyle n={\frac {c}{v}},} n={\frac {c}{v}},
where c is the speed of light in vacuum and v is the phase velocity of light in the medium. For example, the refractive index of water is 1.333, meaning that light travels 1.333 times as fast in vacuum as in water.
Illustration of the incidence and refraction angles
Refraction of a light ray
The refractive index determines how much the path of light is bent, or refracted, when entering a material. This is described by Snell's law of refraction, n1 sinθ1 = n2 sinθ2, where θ1 and θ2 are the angles of incidence and refraction, respectively, of a ray crossing the interface between two media with refractive indices n1 and n2. The refractive indices also determine the amount of light that is reflected when reaching the interface, as well as the critical angle for total internal reflection and Brewster's angle.