On placing a thin film of mica of thickness `12xx10^(-5)cm` in the path of one of the interfering beams in young's double slit experiment using monochromatic light, the fringe pattern shifts through a distance equal to the width of a bright fringe. If `lamda=6xx10^(-5)cm`, the refractive index of mica is

Options

A. 1.1
B. 1.3
C. 1.5
D. 1.4

Answer

C

Explanation

`S=(mu-1)txx(D)/(d)" but "X=(lamdaD)/(d)" "therefore (D)/(d)=(X)/(lamda)`
and S=X
`X=(mu-1)txx(X)/(lamda)`
`therefore (mu-1)t=lamda" "therefore (mu-1)xx12xx10^(-5)=6xx10^(-5)`
`therefore mu-1+0.5=1.5`