# The refractive index is_______________

The refractive index is the ratio of the sine of the angle of incidence to the sine of the angle of refraction.

### Explanation

The ratio between the speed of light in medium to speed in a vacuum is the refractive index.

• Refractive index is defined as the bending of light rays while the light ray enters from one medium to another. It is denoted by the letter n.
$n=\frac{\sin i}{\sin r}$

here n is a constant value which is recognized as the refractive index of medium ‘b’, in regards to medium ‘a’.

• The Refractive index of a medium is also defined as the ratio of the speed of light in air or vacuum and the speed of light in that medium. If the speed of light in air is c and the speed of light in the medium is v then the refractive index of the medium is articulated as,
$n=\frac{c}{v}$

Where,

n is the refractive index
c is the velocity of light in a vacuum ( 3 × 108 m/s)
v is the velocity of light in a substance