1. The problem statement, all variables and given/known data A thin layer of water (n=1.33) is surrounded by air what wavelength of light will not be transmitted through the water at the point where the water is 113 nm thick? 3. The attempt at a solution - In phase - Path difference of 2T. - Constructive Interference I just don't know how to set up the formula to find the wavelength. I know to find the wavelength in water I divide wavelenght in air by the index of refraction of water. Any help appreciated, cheers.