When a thin layer of alcohol (nalcohol = 1.39) is poured over a glass plate (nglass = 1.52), reflected monochromatic light from
the plate is enhanced when = 640 nm and eliminated when = 512 nm. Determine the minimum possible thickness of the alcohol layer such that the above conditions are simultaneously met. Assume that nair = 1.0 and that the light is incident perpendicular to the plate.
