A parallel beam of monochromatic light of wavelength $5000 \AA$ is incident normally on a single nar

Question

A parallel beam of monochromatic light of wavelength $5000 \AA$ is incident normally on a single narrow slit of width 0.001 mm . The light is focused by convex lens on screen, placed on its focal plane. The first minima will be formed for the angle of diffraction of _______ (degree).\

Professor PC Thomas Classes · Answer

(30) : Given : $\lambda=5000 \AA, d=0.001 \mathrm{~mm}$ first minima, $n=1$\ Condition for minima is\ $\Rightarrow \quad d \sin 	heta=n \lambda ; d \sin 	heta=\lambda$\ $\Rightarrow \sin 	heta=\frac{5000 	imes 10^{-10}}{0.001 	imes 10^{-3}}=0.5$\ $\Rightarrow 	heta=30^{\circ}$\