Hi, I'm a high school physics student and I'm having a lot of trouble with thin film interference 1. The problem statement, all variables and given/known data A thin layer of oil (noil=1.25) is floating on water (n=1.33). How thick is the oil in the region that strongly reflects green light (λ=556nm)? 2. Relevant equations noil/nwater = λwater/λoil t = mλ/2, where t is thickness of the film, m is order of interference maxima (i'm not sure about this one) 3. The attempt at a solution 1.25/1.33 = 556/λ λ=592 nm t=mλ/2 =(1)(592)/2 =296 nm (ans in book 222 nm) I'm not entirely sure of what I'm doing here. I'm trying to just find the right formula to plug the variables in and I don't grasp the principles behind it. If someone could shed some light on the subject and provide some tips on how to solve similar problems it would be greatly appreciated.