Q. A beam of light of wavelength $600\ nm$ from a distant source falls on a single slit $1\ mm$ wide and the resulting diffraction pattern is observed on a screen $2\ m$ away. The distance between the first dark fringes on either side of the central bright fringe is
A) $1.2\ mm$
B) $1.2\ cm$
C) $2.4\ cm$
D) $2.4\ mm$
Explanation
(d) Distance between the first dark fringes on either side of central maxima = width of central maxima $= \frac{2\lambda D}{d} = \frac{2 \times 600 \times 10^{- 9} \times 2}{1 \times 10^{- 3}} = 2.4\ mm$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.