Ufa State Aviation Technical University EXAMINATION TICKET NO. 38 A1. To enlighten the lens (n,=1.5), a thin film whose refractive index is n_(2)= 1.28 is applied to the surface of the lens. Light from lambda =0.55 um normally falls on the lens. At what minimum film thickness the reflected rays are maximally attenuated __ jim 4. 0.5 1. 0.4 2. 0,3 3. 0.2

To solve this problem, we need to use the formula for thin film interference: where:- is the refractive index of the thin film,- is the thickness of the film,- is an integer (1, 2, 3,...),- is the wavelength of the light.Given:- - umWe need to find the minimum film thickness for which the reflected rays are maximally attenuated. This occurs when .Substituting the given values into the formula: Solving for : Therefore, the minimum film thickness at which the reflected rays are maximally attenuated is approximately 0.215 um. The closest answer from the given options is:3. 0.2