Question

A parallel beam of wavelength $\lambda = 4500\,A^\circ$ passes through a long slit of width $2 \times 10^{-4}\, m$ . The angular, divergence for which most of the light is diffracted is ( in $\times10^{-5}$ radian)

• A. $\frac{2\pi}{3}$
• B. $\frac{5\pi}{4}$
• C. $\frac{3\pi}{4}$
• D. $\frac{\pi}{3}$

Answer 1

Answer: (B)

$\frac{5\pi}{4}$

Answer 2

$a$ sin $\theta = n \lambda$ ; $\theta = \frac{\lambda}{a} \frac{n \pi}{180} rad$