Question

A monochromatic light of `lambda=5000Å` is inciden on two slits seperated by a distance of `5xx10^(-4)m.` if a thin glass of thickness `1.5xx10^(-6)` m and refractive index `1.5` placed between one of the slits and screen. The pahses difference introduced at the position of central maxima is
A. `3pi `
B. `2 pi`
C. `2pi//3`
D. `pi//3`

Answer 1

Correct Answer - A
Path difference `(mu-1)t=(1.5-1)1.5xx10^(-6)`
Phase difference `=(2pi)/(lamda)xx(mu-1)t`
`=(2pixx0.5xx1.5xx10^(-6))/(5ccx10)`
`=3pi`