Question

what is total internal reflection

Answer 1

the complete reflection of a light ray reaching an interface with a less dense medium when the angle of incidence exceeds the critical angle.

Answer 2

the total internal reflection is defined as the way and Ray of light is passing through the denser medium to the rarer medium at an angle greater than the critical angle then the incident ray bounces back by making the same angle into the denser medium it is called the TIR .