# Is refractive index vector or scalar? What are its units? What happens to the wavelength while...

## Question:

Is refractive index vector or scalar? What are its units? What happens to the wavelength while traveling from a rarer to a denser medium?

## Refractive Index

Refractive index is a property of a material to bend the light while entering into that material. It is the ratio of velocity of light in free space to the velocity of light in that medium. It is closely related to the density of the material.

## Answer and Explanation:

Refractive index is the ratio of velocity of light in vaccum to the velocity of light in medium. Therefore it is a dimensionless quantity. It is a scalar quantity.

Based on the speed of light in a medium, materials are classified into rarer and denser media. In rarer medium the light has more speed and therefore more wavelength. In a denser medium, the speed of light is low and therefore the wavelength also. That is when a light wave travels from a rarer medium to denser, the wavelength of light decreases.