a film of index of refraction of 1.4 and thickness of 1.2*10^-5 m is on a lens with an index of refraction of 1.6. Light of wavelength 600 nm is incident normally from air to the film. Consider only reflections from the top and botom surfaces of the film.
a) how many reflected waves will experience the 180 degree phase shift?
b) what is the path length difference between the two reflected rays?
c) will the reflected waves interfere constructively or destructively?