Question

At the first minimum adjacent to the central maximum of a single-slit diffraction pattern the phase difference between the Huygens wavelet from the edge of the slit and the wavelet from the mid-point of the slit is
A. (a) `pi/8` radian
B. (b) `pi/4` radian
C. (c) `2pi` radian
D. (d) `pi` radian

Answer 1

Correct Answer - D
For first minima at P, `a sin theta=lambda`
So phase difference `Deltalambda_1=(Deltax_1)/(lambda)xx2pi=((a//2)sintheta)/(lambda)xx2pi`

`Deltaphi_1=(lambda)/(2lambda)xx2pi=piradian`