The packet doesn't explain this concept very well, and the book doesn't seem to explain it at all. A glass surface (n = 1.5) is coated with a film with an index of refraction n=1.3. If light of frequency 6x10^14 cps is incident almost normally on the film, find the minimum thickness that will cause (a) reflection, and (b) non-reflection. Any tips on the concept or any formulas woluld be very helpful. Thanks!