COMEDK Exam 2019 Solved Paper

Given, wavelength of light beam,
λ‌=600‌nm
‌=600×10−9m
Distance between slits, d=1‌mm=10−3m
Distance between slits and screen, D=2m
Distance between first dark fringes from the central bright fringe, 2β= ?
As we know, fringe width, β=‌

λD

d

‌=‌

600×10−9×2

10−3

‌=1.2×10−3m
Distance between first dark fringes on either side of central bright fringe (2β)=2×β=2×1.2×10−3m
⇒‌‌2β=2.4‌mm