I forgot to mention that, since this is the third bright ring, this must be the third instance of constructive interference, so that the thickness of the film at that point must equal (3/2)λ, but I do not know where to go from there.
Homework Statement
Newton's rings can be seen when a planoconvex lens is placed on a flat glass surface. For a particular lens with an index of refraction of n= 1.51 and a glass plate with an index of n= 1.78, the diameter of the third bright ring is 0.760 mm.
If water (n= 1.33) now fills...