Question

State the condition under which total internal reflection occurs. Give the mathematical expression for total internal reflection.

Answer 1

• When the angle of incidence exceeds the critical angle, the angle of refraction exceeds 90°. When such rays return to the same denser media, all the light is reflected into the denser medium, resulting in total internal reflection.
• Expression for total internal reflection:
  ₁n₂ = sin C
  C = critical angle and n₂ = refractive index of the rarer medium (1 w.r.t. denser medium 2).