In a Young's double slit experiment, the separation between the slits is halved and distance between the slits and screen is doubled. The fringe width will be
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Quadrupled
The fringe width in Young’s double slit experiment is directly proportional to the screen distance D and inversely proportional to the slit separation d.
\( \displaystyle \beta = \frac{\lambda D}{d} \)
With \( d' = d/2 \) and \( D' = 2D \):
\( \displaystyle \beta' = \frac{\lambda (2D)}{d/2} = 4\,\frac{\lambda D}{d} \)
\( \displaystyle \beta' = 4\beta \)