In Figure a, the waves along rays 1 and 2 are initially in phase, with the same wavelength in air. Ray 2 goes through

In Figure a, 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 0 that, from L = 0 to L_s = 900 nm, the intensity I of the light at point P varies with L as given in Figure. At what values of L greater than L_s is intensity I

(a) Maximum and

(b) Zero?

(c) What multiple of A gives the phase difference between ray 1 and ray 2 at common point P when L = 1200 nm?

Screen Ray 2 Ray 1 Ls L (nm)