Question

A light beam undergoes total internal reflection at the interface between medium A and medium B when traveling from A to B. Which medium has the greater index of refraction? a) Medium A b) Medium B c) Either

Answer 1

a) Medium A

Step-by-step explanation:

According to Snell's law:

`n_i* {sin\theta_i}={n_r}*{sin\theta_r}`

Where,

`{\theta_i}` is the angle of incidence

`{\theta_r}` is the angle of refraction

`{n_r}` is the refractive index of the refraction medium

`{n_i}` is the refractive index of the incidence medium

The angle of refraction increases as the angle of incidence.

At one particular angle, which is known as critical angle, refracted light does not enter the rarer medium but instead travels along surface between two media. If ray is incident at greater than the critical angle, then refracted ray reflects back into denser medium which results into total internal reflection.

The two important conditions for the total internal reflection are:

• Angle of incidence should be greater than critical angle.
• Ray should travel from the denser medium to the rarer medium.

Hence, A has greater value of refractive index.