Chapter 35, Problem 87P

SSM In Fig. 35-51a, the waves along rays 1 and 2 are initially in phase, with the same wavelength λ in air. Ray 2 goes through a material with length L and index of refraction n. The rays are then reflected by mirrors to a common point P on a screen. Suppose that we can vary L from 0 to 2400 nm. Suppose also that, from L = 0 to Ls = 900 nm, the intensity I of the light at point P varies with L as given in Fig. 35-52. At what values of L greater than Ls is intensity I (a) maximum and (b) zero? (c) What multiple of λ gives the phase difference between ray 1 and ray 2 at common point P when L = 1200 nm?

Figure 35-52 Problem 87.