A ring of wire is dipped into a soap solution and it is held so that the soap film on the ring is vertical. As the soap film gradually drains toward the bottom, a dark band appears at the top with alternating bright and dark bands of light appear along the length on the film. Determine the thickness of the film at the first three bright bands, as counted from the top, if the incident light has a wavelength of 600 nm and is directed almost perpendicular to the surface of the film. The index of refraction of the soap solution is 1.33.