Q. A slit of width a is illuminated with a monochromatic light of wavelength $\ \lambda$ from a distant source and the diffraction pattern is observed on a screen placed at a distance D from the slit. To increase the width of the central maximum one should
A) Decrease D
B) Decrease $a$
C) Decrease $\lambda$
D) The width cannot be changed
Explanation
(b) Width of the central maximum,
$\beta_{0} = \frac{2D\lambda}{a}$
$\beta_{0} \propto \frac{1}{a}$
$\therefore$ To increase the width of the central maximum one should decrease $a.$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.