In Young's double slit experiment, the fringes are displaced index 1.5 is introduced in the path of one of the beams. When this plate in replaced by another plate of the same thickness, the shift of fringes is `(3//2)x`. The refractive index of the second plate is

Options

A. (a) `1.75`
B. (b) `1.50`
C. (c) `1.25`
D. (d) `1.00`

Answer

B

Explanation

Fringes shift is given by `x=((mu-1)tbeta)/(lambda)`. For first plate,
`x=((mu_1-1)tbeta)/(lambda)`
For second plate `3/2x=((mu-1)tbeta)/(lambda)`
`implies((mu_2-1)/(mu_1-1))=3/2implies((mu_2-1)/(1.5-1))=3/2`
`impliesmu_2=1.75`