Ray Optics and Optical Instrument - Reversibility of Light

Law of Reversibility: When the ray of light reverse back to its own path after refraction and reflection, this phenomenon is called Reversibility.

Multiply both equation.

¹n₂ X ²n₁ = 1

When the light ray passes though multi medium

At 1^st Interface

At 2^nd Interface

At 3^rd interface

Multiplying equation (i), (ii) & (iii)

Apparent depth

If C is very close to A, then OC = OA = real and IC = IA = Apparent

²n₁ = Apparent Depth / Real Depth

apparent depth = n X real depth

Change in depth = real depth – apparent depth

Shift in depth = OA - ²n₁ X OR

                         = OA (1 - ²n₁)