The outer surface of a transparent glass slab of refractive index `mu_(S)=1.5` is coated by a thin layer of transparent medium of refractive index `mu_(C)=1.6`. Orange light of wavelength 6400Å falls normally on the coating. The reflected light at the upper surface and at the lower surface of teh coat interfere destructively. If thickness of the coat is `5Kxx10^(-8)`m, calculate the minimum value of K.

Answer

4