Question

What do you understand by the following terms,

(i) Total internal reflection

(ii) Critical angle

Answer 1

• (i) Total internal reflection: The phenomenon due to which a ray of light, while traveling from an optically denser medium to an optically rarer medium, gets reflected into the optically denser medium, at the surface of separation is called total internal reflection.
• During total internal reflection, no light energy is absorbed by the surface of separation and the entire amount of it is reflected.
• (ii) Critical angle: Angle of incidence in a denser medium, for which the angle of refraction in the rarer medium is $90°$ is called the critical angle.
• The critical angle for glass is $42°$and for water it is $48°$.