Q. In Young’s double slit experiment, distance between two sources is $0.1\ mm$. The distance of screen from the sources is $20\ cm$. Wavelength of light used is $5460\ \mathring{\mathrm{A}}$. Then angular position of the first dark fringe is
A) $0.08{^\circ}$
B) $0.18{^\circ}$
C) $0.20{^\circ}$
D) $0.313{^\circ}$
Explanation
(d) Angular position of first dark fringe
$\theta = \frac{\lambda}{d} = \frac{5460 \times 10^{- 10}}{0.1 \times 10^{- 3}} \times \frac{180}{\pi}$ (in degree)
$= 0.313{^\circ}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.