A 1.25 refractive index thin film on a 1.50 refractive index glass window is made to reflect infrared radiation of wave-length 1000 nm. What is the net reflective phase change of infrared radiation reflected off the front surface of the thin film relative to the radiation reflected off the back surface of the
film and returning to the front?
(a) Zero (b) 1/4 wavelength
(c) 1/2 wavelength (d) None of these