Question

Answer the following questions:
(a) What is total internal reflection?
(b) State two conditions necessary for the total internal reflection to occur.
(c) Draw diagrams to illustrate the total internal reflection.

Answer 1

(a) Total internal reflection is the phenomenon which occurs when light travels from denser to rarer medium at a large angle of incidence. In total internal reflection, light is reflected back to the incident medium and almost no light enters the second medium. The reflected ray follows the laws of reflection.

(b) For total internal reflection to occur, two conditions must be met:

• The angle of incidence of the light ray must exceed the critical angle of the interface.
• Ray must travel from denser to rarer medium.

(c) In the figure shown below, the third case corresponds to that of total internal reflection.