Walker, Halliday & Resnick — Interference: Problem 3

In Fig. 35-22, light is incident perpendicularly on a thin layer of material 2 that lies between (thicker) materials 1 and 3. (The rays are tilted only for clarity.) The waves of rays \( r_1 \) and \( r_2 \) interfere, and here we consider the type of interference to be either maximum (max) or minimum (min). For this situation, Problem 3 in Table 35-2 refers to the indexes of refraction \( n_1 = 1.50, n_2 = 1.34, \) and \( n_3 = 1.76, \) the type of interference being "min", and the thin-layer thickness \( L = 380 \text{ nm.} \) Give the wavelength \( \lambda \) (in nanometers, measured in air) that is in the visible range.