Question

If Young's double slit experiment is performed in water :

• A. the fringe width will decrease
• B. the fringe width will increase
• C. the fringe width will remain unchanged
• D. there will be no change

Answer 1

The correct option is A the fringe width will decrease

As we know
$\beta =\frac{D\lambda }{d}........\left(i\right)$
and $\lambda \propto \frac{1}{\mu }..........\left(ii\right)$
From Eqs $\left(i\right)$ and $\left(ii\right)$
$\beta \propto \lambda \propto \frac{1}{\mu }$
$\therefore$ $\beta \propto \frac{1}{\mu }$
Hence (a) is correct