Aplane wave of monochromatic light is incident normally on a uniformly thin film of oil that covers a glass plate. the wavelength of the source can be varied continuously. fully destructive interference of the reflected light is observed for wavelengths of 517 and 632 nm and for no wavelengths in between. if the index of refraction of the oil is 1.33 and that of the glass is 1.50, find the thickness of the oil film.

When a vertical beam of light passes through a transparent medium, the rate at which its intensity i decreases is proportional to i(t), where t represents the thickness of the medium (in feet). in clear seawater, the intensity 3 feet below the surface is 25% of the initial intensity i0 of the incident beam. what is the intensity of the beam "10" feet below the surface? (give your answer in terms of i0. round any constants or coefficients to five decimal places.)