(Solved): A thin film of soap with \( n=1.40 \) hanging in the air reflects dominantly red light with \( \lam ...

A thin film of soap with \( n=1.40 \) hanging in the air reflects dominantly red light with \( \lambda \) \( =631 \mathrm{~nm} \). What is the minimum thickness of the film? Now this film is on a sheet of glass, with \( \mathrm{n}= \) 1.52. What is the wavelength of the light in air that will now be predominantly reflected?