1. The problem statement, all variables and given/known data Monochromatic beam of incident light on the surface of the glass wedge, whose upper edge is inclined at an angle of γ = 0.05 ° from the base. In reflected light observe a number of interference fringes, the distance between adjacent dark streaks is △X = 0.21 mm. Calculate the wavelength λ of the incident light. Refractive index of glass n = 1.5. 2. Relevant equations [tex] d \sin \alpha = n \lambda [/tex] 3. The attempt at a solution I need a guidance ! Is it a thin-film problem ?