Q.
In double slit experiment, the distance between two slits is 0.6 mm and these are illumunated with light of wavelength 4800A˚ . The angular width of first dark fringe on the screen distant 120cm from slits will be :
Angular fringe width of first minima is D2x=2(2n−1)2dA =(2n−1)dλ
Given, d=0.6mm=0.6×10−3m λ=4800AA=4.8×10−7m,n=1 ∴D2x=0.6×10−3(2×1−1)×4.8×10−7 =8×10−4rad.