Q 12-10-162JEE MainJEE Main 2025 (4 Apr, Shift 1)Easy
In a Young's double slit experiment, the slits are separated by $0.2\ \text{mm}$. If the slit separation is increased to $0.4\ \text{mm}$, the percentage change of the fringe width is:
Answer: (C) $50\%$
$\beta = \dfrac{\lambda D}{d}$, so doubling $d$ halves the fringe width: a $50\%$ change (a decrease).
Solution by Sreeraj P, M.Sc Physics