Question

At the first minimum 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. $\pi \text{rad}$
• B. $\frac{\pi }{4}\text{rad}$
• C. $\frac{\pi }{2}\text{rad}$
• D. $\frac{\pi }{8}\text{rad}$

Answer 1

The correct option is A $\pi \text{rad}$


For first minima at $P,\Delta x=\frac{\lambda }{2}$
So phase difference $\Delta \varphi =\frac{\Delta x}{\lambda }\times 2\pi$
$=\frac{\left(\frac{\lambda }{2}\right)}{\lambda }\times 2\pi =\pi \text{rad}$

Hence, $\left(D\right)$ is the correct answer.