Question

In placing a thin sheet of mica of thickness $12\times {10}^{-5}cm$ in the path of one of the interfering to beam in YDSE, the central fringe shifts equal to a fringe width. Find the refractive index of mica. Given $\lambda =600nm$.

• A. $1.5$
• B. $1.48$
• C. $1.61$
• D. $1.56$

Answer 1

The correct option is A $1.5$

We have
$\beta =\frac{\lambda D}{d}=(\mu -1)t\frac{D}{d}$
$⟹\mu =\frac{\lambda }{t}+1=1.5$