Lag1989 task №20.40

The soap film, located vertically, forms a wedge due to liquid drainage. Observing the interference fringes in the reflected light of the mercury arc (λ= 546.1 nm), we find that the distance between the five fringes is L = 2 cm. Find the angle θ of the wedge. The light falls perpendicular to the surface of the film. The refractive index of soapy water is n = 1.33.