Question

A thin mica sheet of thickness `4xx10^(-6)` m and refractive index `(mu=1.5)` is introduced in the path of the light from upper slit. The wavelength of the wave used is `5000 Å` The central bright maximum will shift
A. 4 fringes upward
B. 2 fringes downward
C. 10 fringes upward
D. None of these

Answer 1

Correct Answer - A
On introducing mica sheet, fringe shift `=beta/lambda(mu-1)t`
where, t is thickness of sheet
So, shift `beta/((5000xx10^(-10)))xx(1.5-1)xx(4xx10^(-6))=4beta`
So, central bright maximum will shift 4 fringes upward