A thin film of a specific meterial can be used to decrease the intensity of reflected light. There is destrucive inteference of wave reflected from upper and lower surface of the film. These films are called non-reflecting or anti-reflecting coatings. The process of coating the lens or surface with non-reflecting film is called blooming as shown in figure The refracting index of coating `(n_(1))` is less than that of the glass `(n_(2))`.

6. If the thickness of film in above question in not technologically possible to manufacture, then next thickness of film required is (approximately)

Options

A. 300 nm
B. 125 nm
C. 750 nm
D. 550 nm

Answer

a

Explanation

`2 n_(1) t = (3 lambda)/(2) implies t = 3 t_(min) ~= 300 nm`