Question

In Fraunhoffer diffraction, at the angular position of first diffraction minimum, phase difference (in radian) between wavelets from opposite edges of the slit is

• A. $\frac{\pi }{2}$
• B. $\pi$
• C. $2\pi$
• D. $4\pi$

Answer 1

The correct option is C $2\pi$

Path difference when rays are diffracted from the edge

$\Delta x=\lambda$

Phase difference, $\varphi =\frac{2\pi }{\lambda }\times \Delta x$

$\varphi =\frac{2\pi }{\lambda }\times \lambda =2\pi$

The correct option is C.