k transparent slabs are arranged one over another. The refractive indices of the slabs are μ1, μ2, μ3, … μk and the thickness are t1, t2, t3, … tk. An object is seen through this combination with nearly perpendicular light. Find the equivalent refractive index of the system which will allow the image to be formed at the same place.

Total number of transparent slabs= k

Thickness of the slabs= t1, t2, t3, … tk

Refractive index= μ1, μ2, μ3, … μk

Then the shift can be written as

= . (1)

= …………(2)