Wave Optics - Result Question 29
31. At the first minimum adjacent to the central maximum of a single-slit diffraction pattern, the phase difference between the Huygen’s wavelet from the edge of the slit and the wavelet from the midpoint of the slit is :
[2015 RS]
(a) $\frac{\pi}{2}$ radian
(b) $\pi$ radian
(c) $\frac{\pi}{8}$ radian
(d) $\frac{\pi}{4}$ radian
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Answer:
Correct Answer: 31. (b)
Solution:
- (b) For first minima at $P$
$AP-BP=\lambda$
$AP-MP=\frac{\lambda}{2}$
So phase difference, $\phi=\frac{2 \pi}{\lambda} \times \frac{\lambda}{2}=\pi$ radian
