In the ideal double-slit experiment, when a glass-plate (refractive index 1.5) of thickness t is introduced in the path of one of the interfering beams (wavelength `lambda`), the intensity at the position where the central maximum occurred previously remains unchanged. The minimum thickness of the glass-plate is

Options

A. (a) `2lambda`
B. (b) `(2lambda)/(3)`
C. (c) `lambda/3`
D. (d) `lambda`

Answer

A

Explanation

According to given condition
`(mu-1)t=nlambda` for minimum t, `n=1`
So, `(mu-1)t_(min)=lambda`
`t_(min)=(lambda)/(mu-1)=(lambda)/(1.5-1)=2lambda`