A soap film (n = 1.33) is 290 nm thick and lies on a glass plate (n = 1.52). Sunlight, whose wavelengths (in vacuum) extend from 380 to 750 nm, travels through air and strikes the film perpendicularly. What is the vacuum wavelength vacuum in the visible range (380 nm to 750 nm) at which destructive interference causes the film to look dark in reflected light?