What does a rainbow look like through dark glasses?
This is a “trick” question because the answer depends on whether or not your glasses are Polaroid. When light is reflected at certain angles it becomes polarized (discussed again quite well in Nussenzveig’s article), and it has been found that the rainbow angle is close to that angle of reflection at which incident, unpolarized light (sunlight) is almost completely polarized. So if you look at a rainbow with Polaroid sunglasses and rotate the lenses around the line of sight, part of the rainbow will disappear!
