A soap film (n = 1.33) is contained within a rectangular wire frame. The frame is held vertically so that the film drains downward and forms a wedge with flat faces. The thickness of the film at the top is essentially zero.
The film is viewed in reflected white light with near-normal incidence, and the first violet (A = 420 nm) interference band is observed 3.00 cm from the top edge of the film.
(a) Locate the first red (A = 680 nm) interference band.
(b) Determine the film thickness at the positions of the violet and red bands.
(c) What is the wedge angle of the film?