(a) If a thin liquid film floating on water has an index of refraction less than that of water, will the film appear bright or dark in reflected light as its thickness goes to zero?
(b) Choose the best explanation from among the following:
I. The film will appear bright because as the thickness of the film goes to zero the phase difference for reflected rays goes to zero.
II. The film will appear dark because there is a phase change at both interfaces, and this will cause destructive interference of the reflected rays.