JEE Main 2026 — 23 January, Morning Shift — Question 47

In two separate Young's double-slit experimental set-ups, two monochromatic light sources of different wavelengths are used to get fringes of equal width. The ratios of the slit separations and that of the wavelengths of light used are $2: 1$ and $1: 2$ respectively. The corresponding ratio of the distances between the slits and the respective screens ( $\mathrm{D}_{1} / \mathrm{D}_{2}$ ) is $\_\_\_\_$。