Question

Thin Film Interference Problems 1. Oil (n=1.25) floats on water. What is the minimum thickness of oil in a region where it appears green ( = 525 nm)? (Ans: 210 nm) 2. A 500 nm thick layer of oil (n = 1.25) floats on water. What wavelengths of light in the visible range (400 nm to 700 nm) are maximally reflected? (Ans: 417 nm, 625 nm) 3. Athin film of acetone (n = 1.25) coats a thick glass plate (n = 1.50). White light is incident normal to the film. In the reflections, fully destructive interference occurs at 600 nm and fully constructive interference at 700 nm. Calculate the thickness of the acetone film. [Ans: 840 nm)

Answer 1