On a rainy day, when the pavement is covered by water, a thin film of oil has gathered on top of the water. The oil layer (n = 1.25) is sandwiched between air (n = 1) on top and water (n = 1.333) below. a) When viewed at normal incidence (perpendicular to the surface), the film of oil reflects most strongly red light with a wavelength of 640 nm. Calculate three possible values for the thickness of the film. b) When viewed at normal incidence, the same film of oil does not reflect any green light with a wavelength of 512 nm. Calculate the exact thickness of the film.

On a rainy day, when the pavement is covered by water, a thin film of oil has gathered on top of the water. The oil layer (n = 1.25) is sandwiched between air (n = 1) on top and water (n = 1.333) below. a) When viewed at normal incidence (perpendicular to the surface), the film of oil reflects most strongly red light with a wavelength of 640 nm. Calculate three possible values for the thickness of the film. b) When viewed at normal incidence, the same film of oil does not reflect any green light with a wavelength of 512 nm. Calculate the exact thickness of the film.