042-Fundamentals-of-Physics-II-Electromagnetism-Optics-and-Quantum-Mechanics-R.-Shankar-Edisi-1-2016 · Problem 18.8.1

Wave Theory of Light

Physics — Shankar · thin-film-interference-normal-incidence

Problem

A film of oil (refractive index

n_0 = 1.5

) on water produces constructive interference for

\lambda = 400\,\text{nm}

and destructive interference for

\lambda = 500\,\text{nm}

. What is the thickness

\delta

of the oil film? Find the smallest value of

\delta

satisfying both conditions.