**Refractive Index**

**Snell's Law**

Two media of refractive indices

**n**and

_{1}**n**meet at a surface or interface.

_{2}**i**incident angle and

**r**is reflected angle

For air to dense medium we can simplify this equation by assuming refractive index in air is one (n

_{1}= 1). Now we can simply write refractive index

**n**

The speed of all electromagnetic radiation in vacuum is the same, approximately 3x10

^{8}meters per second, and is denoted by

**c**. Therefore, if

**v**is the phase velocity of radiation of a specific frequency in a specific material, the refractive index is given by