Question

With a neat ray diagram, explain the concept of total internal reflection (TIR). 

Explain total internal reflection with a ray diagram.

Answer 1

1. Total internal reflection is the phenomenon that occurs when a propagated wave strikes the boundary of a medium at an angle greater than a specific critical angle relative to the normal of the surface.
2. It refers to the complete reflection of a ray of light within a given medium from the surrounding surface. Hence, the ray of light continues to be reflected within the medium (glass, water, etc.) without being refracted.
3. When a ray of light passes from a denser medium to a rarer medium, increasing the angle of incidence relative to the normal leads to a specific condition at the critical angle (θc), where the refracted ray becomes parallel to the boundary surface.
4. If any ray of light moves from a denser medium to a rarer medium and strikes the boundary surface with an incident angle greater than the critical angle, it will continue to be reflected within the denser medium instead of being refracted.