Question

In Young's experiment, if separate between slits is made half, then fringe width will become:

• A. double
• B. four times
• C. half
• D. remains same

Answer 1

Answer: (A)

Fringe width $\beta =\frac{\lambda D}{d}$
$D=$ distance between slits and screen.
$d=$ separation between slits.
${\beta }^{\prime }=\frac{\lambda D}{d/2}=2\left(\frac{\lambda D}{d}\right)$
fringe width becomes double.