Q. Direction of the first secondary maximum in the Fraunhoffer diffraction pattern at a single slit is given by ($a$ is the width of the slit)
A) $a\sin\theta = \frac{\lambda}{2}$
B) $a\cos\theta = \frac{3\lambda}{2}$
C) $a\sin\theta = \lambda$
D) $a\sin\theta = \frac{3\lambda}{2}$
Explanation
(d) For $n^{th}$ secondary maxima path difference
$d\sin\theta = (2n + 1)\frac{\lambda}{2} \Rightarrow a\sin\theta = \frac{3\lambda}{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.