Question

Medium in which speed of light is less is known as
(A) Optically rarer medium
(B) Optically transparent medium
(C) Optically denser medium
(D) None

Answer 1

Hint:
A medium in which the light passes with more speed is known as an optically rarer medium. A medium in which the light passes through it without experiencing any difficulty or obstruction is called an optically transparent medium. A medium in which the speed of light is less than usual is known as an optically denser medium.

Complete step-by-step answer:
Light travels with different speeds in a different medium and due to this property of light, we encounter a phenomenon called refraction of light. The change in the direction of light when passing from one medium to another. This phenomenon is called the refraction of light.

The light ray passes from one medium to another, it experiences the change in the path of the ray of light. Here in the above diagram, the incident ray passing through the glass slab changes its path moving from air to the glass and then glass to air.
We define two types of medium according to the speed of light in that medium relative to other mediums.
1. Optically rarer medium: In this medium speed of light is more.
2. Optically denser medium: In this medium speed of light is less.
Thus, “optically denser medium” is the answer.
Hence, option (C) is the correct option.

Additional information:
*Refraction is phenomena that exist due to change in the speed of light in a different medium.
*When light rays travel from optically rarer medium to denser medium they bend towards the normal, i.e., angle of incidence is more than the angle of refraction.
*Similarly when light rays travel from optically denser medium to optically rarer medium it bends away from the normal, i.e., angle of incidence if less than the angle of refraction.

Note:
*Mostly we use this concept of the rarer and denser medium in comparing two mediums.
*For example, water is denser medium than air and glass is denser medium than air and water.
*So in question whatever mediums are given we have to compare them and accordingly say which one will be rarer and which will be denser.