Q. Light of wavelength $\lambda$ is incident on a slit of width$d$. The resulting diffraction pattern is observed on a screen at a distance$D$. The linear width of the principal maximum is equal to the width of the slit, if $D$ equals
A) $\frac{d^{2}}{2\lambda}$
B) $\frac{d}{\lambda}$
C) $\frac{2\lambda^{2}}{d}$
D) $\frac{2\lambda}{d}$
Explanation
(a) The linear width of central principal maximum
$= \frac{2\lambda D}{d}$
If it is equal to width of slit $(d)$, then
$\frac{2\lambda D}{d} = d\ or\ D = \frac{d^{2}}{2\lambda}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.