A ray of light from a monochromatic point source of light is incident at a point on the screen. If a thin mica film of thickness ' t ' and refractive index ' n ' is introduced in its path, then the optical path

Step-by-step solution

Optical path length is defined as the product of geometric path length and refractive index, representing the equivalent vacuum distance light travels in the same time. For a geometric path segment of length t , the initial optical path in air ( n_ air = 1 ) is OP_ initial = t 1 = t . Introducing a mica film of thickness t and refractive index n > 1 changes the optical path to OP_ final = t n = nt . The change in optical path is OP = OP_ final - OP_ initial = nt - t = (n - 1)t . Since n > 1 , the term (n - 1) is po