What is the minimum thickness of thin film required for constructive interference in the reflected light through it ?
(Given, the refractive index of the film `=1.5,` wavelength of the lilght incident on the film `=600` nm.

Options

A. 100nm
B. 200 nm
C. 50 nm
D. 200 nm

Answer

A

Explanation

Condition for constructive interference
`2mut= (2n+1) lambda//2`
For minimum thickness n=0
`t= (600 xx 10^(-9))/(4 xx 1.5) = 100 nm`