Fringe width in double slit: β=dλD
Given: d2d1=2:1 and λ2λ1=1:2, with equal fringe widths
For equal fringe widths: d1λ1D1=d2λ2D2
λ2λ1×D2D1=d2d1
21×D2D1=2
D2D1=4
In two separate Young's double-slit experimental set-ups and two monochromatic light sources of different wavelengths are used to get fringes of equal width. The ratios of the slits 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 (D1/D2) is ____.
Held on 23 Jan 2026 · Verified 6 Jul 2026.
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