1. Sunlight incident on a screen containing two long narrow slits 0.2mm apart casts a pattern on a white sheet of paper 2m beyond. What is the distance (in mm) separating the violet (lambda = 400nm) in the first-order band from the red (lambda = 600nm) in the second order?
2. A soap film has an index of refraction of 1.334. How thick (in nm) is the film if one-half of a wavelength of red light (with a vacuum wavelength of 700nm)extends from one surface across the film to the other surface?
3. A think film of ethyl alcohol (n = 1.36) spread on a at glass plate and illuminated with white light shows a lovely color pattern in reflection. If a region of the film reflects only green light (500nm) strongly, what is its minimum thickness (in nm)?