Question

The phenomenon by which the incident light falling on a surface is sent back into the same medium is known as –
A.Refraction
B.Reflection
C.Total internal reflection
D.Both B and C

Answer 1

Hint: In case of refraction, the light ray goes to the second medium. But in case of reflection and total internal reflection, the incident light ray returns to the first medium, none gets refracted. From this, we can easily get the correct answer.

Complete step by step answer:Light travels in a straight line in a homogeneous medium. When it is travelling in one homogeneous medium, and meets the surface of another homogeneous medium, the following effects may occur-reflection, absorption, or refraction of light.
Reflection – When a ray of light passing through a medium is incident on the interface with another medium then, a portion of light returns to the first medium. This phenomenon is known as reflection of light.

Total internal reflection – When a light ray travelling from denser to rarer medium hits the boundary, and the angle of incidence is greater than the critical angle, the total light ray returns to the first medium, and none is refracted. This optical phenomenon is called total internal reflection.

Refraction – When a ray of light travelling in one medium enters another medium obliquely, the light ray changes its direction at the interface. This phenomenon is called refraction of light.

So, we see that, in case of both reflection and total internal reflection, the incident light falling on a surface is sent back into the same medium.
Therefore, the correct answer is (D) Both B and C.

Note:
When a ray of light gets reflected, the angle of incidence is equal to the angle of reflection, and there is no limit for the angle of incidence. But, in case of total internal reflection, the angle of incidence must be greater than the critical angle.