Coating in Lenses!
To ensure almost \(100\)% transmittivity, photographic lenses are often coated with a thin layer of dielectric material. The refractive index of this material is intermediated between that of air and glass (which makes the optical element of the lens). A typically used dielectric film is \(MgF_2 (n = 1.38)\). What should the thickness of the film (\(d\) in Angstrom) be so that at the center of the visible spectrum \((5500 Angstrom)\), there is maximum transmission?
Note : Round off the value of \(d\) to the nearest 1000. (ex. if the value comes out to be 5997, then the answer should be 6000)
Source - NCERT Exemplar Problems