Air (n = 1.00) d = 200 nm T Oil (n = 1.55) Water (n = 1.33) Figure 3: Thin film of oil on water Problem 4 [Interference, 25 points] A thin (200 nm thick) film of oil (n = 1.55) lies on top of a flat sheet of water n = 1.33. Light shines on the layer of oil from above through air n = 1.00. See diagram below. Assume the water layer is very thick. (a) On the diagram below, sketch the reflected rays from the top and bottom of the film, and derive an expression for the relative phase shift o of the reflected light of the top and bottom surface of the film. (b) What is the visible light (750 to 400 nm) wavelength (in nm) for which the maximum amount of light is reflected from the surface? (c) What is the visible light wavelength (in nm) for which the minimum amount of visible light is reflected from the surface? (d) What color will be most strongly reflected from the film? (e) Sketch a graph of the reflectivity of the surface as a function of wavelength across the visible spectrum from 750 to 450 nm. (f) What color would you see when looking from the water, through the film with a bright light on the other side