Question

Explain the term absolute refractive index of a medium and write an expressionto relate it with the speed of light in vaccum

Answer 1

The refractive index of a medium is defined as the ratio of velocity of light in first medium to the velocity of light in that medium.

Mathematically refractive index

is the velocity of light in first medium.

is the velocity of light in second medium i.e the medium under consideration.

Let the first medium is space or vacuum.

Now, the velocity of light in first medium will be c where c is the velocity of light.

Now, the refractive index

v is the velocity of light in second medium i.e medium under consideration.

Now the refractive index obtained is called absolute refractive index.

Hence, the absolute refractive index of a medium is defined as the ratio of the velocity of light in air to the velocity of light in that medium.

Mathematically the absolute refractive index =

Answer 2

It is defined as ratio of velocity of light in air to the velocity of light in medium.