Question

If in Young's double slit experiment, the distance between the two slits is halved and the distance between the slit and screen id doubled, then the fringe width will become

• A. half
• B. double
• C. four times
• D. unchanged

Answer 1

The correct option is C four times

Fringe width $\beta =\frac{\lambda D}{d}$

On $d^{\prime }=\frac{d}{2},D^{\prime }=2D$

New fringe width ${\beta }^{\prime }=\frac{\lambda D^{\prime }}{d^{\prime }}=4\beta$