Chapter 27, Problem 63P

Both sides of a uniform film that has index of refraction n and thickness d are in contact with air. For normal incidence of light, an intensity minimum is observed in the reflected light at λ₂ and an intensity maximum is observed at λ₁, where λ₁ > λ₂. (a) Assuming no intensity minima are observed between λ₁ and λ₂, find an expression for the integer m in Equations 27.13 and 27.14 in terms of the wavelengths λ₁ and λ₂. (b) Assuming n = 1.40, λ₁ = 500 nm, and λ₂ = 370 nm, determine the best estimate for the thickness of the film.