Question

Can the absolute refractive index of a medium with respect to another medium be less than unity? Give reason.

Answer 1

Refractive index:

1. The refractive index is the measure of the bending of light rays when it is allowed to pass from one medium to another.
2. It can also be defined as the ratio of the velocity of a light ray in an empty space to the velocity of light in a medium.
3. The refractive index of a medium can be calculated using the following formula:
   $\mathrm{\eta }=\frac{\mathrm{c}}{\mathrm{v}}$, where $\mathrm{\eta }$ is the refractive index of the medium, $\mathrm{c}$ is the velocity of the light in vacuum, and, $\mathrm{v}$ is the velocity of the light in the medium.

Explanation:

1. The ratio of the speed of light in a vacuum to the speed of light in that medium is the absolute refractive index of that medium.
2. If the absolute refractive index is less than unity, the speed of light in that medium exceeds the speed of light in a vacuum, which is impossible.
3. In a vacuum, the speed of light is always faster than in any other medium.

No, the absolute refractive index of a medium with respect to another medium is not less than the unity.