Question

In the ideal YDSE when a glass plate $(RI=1.5)$ of thickness t is introduced in path of one of interfering beams , the intensity at the position where central maximum occurred previously remains unchanged. The minimum thickness of glass plate is :

• A. $\lambda$
• B. $3\lambda$
• C. $4\lambda$
• D. $2\lambda$

Answer 1

The correct option is D $2\lambda$

$\begin{array}{c}Shift=\frac{D}{d}\left(\mu -1\right)t\\ =\frac{D\lambda }{d}\\ \Rightarrow t=\frac{\lambda }{\mu -1}=2\lambda \\ Hence,\\ optionDcorrectanswer.\end{array}$