Halliday, Resnick & Walker — Interference: Problem 11

1 through 12 Reflection by thin layers. 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, each problem in Table 35-2 refers to the indexes of refraction $n_1, n_2,$ and $n_3,$ the type of interference, the thin-layer thickness $L$ in nanometers, and the wavelength $\lambda$ in nanometers of the light as measured in air. Where $\lambda$ is missing, give the wavelength that is in the visible range. Where $L$ is missing, give the second least thickness or the third least thickness as indicated. Problem 11: $n_1 = 1.68$, $n_2 = 1.59$, $n_3 = 1.41$, Type = min, $L$ = 2nd least, $\lambda = 342$ nm.