Q. In Young’s double slit experiment we get 60 fringes in the field of view of monochromatic light of wavelength 4000$\mathring{\mathrm{A}}$. If we use monochromatic light of wavelength 6000 $\mathring{\mathrm{A}}$, then the number of fringes obtained in the same field of view are
A) 60
B) 90
C) 40
D) 1.5
Explanation
(c) As $x = n_{1}\beta_{1} = n_{2}\beta_{2} = n_{2}\lambda_{1} = n_{2}\lambda_{2}$
$\therefore n_{2} = \frac{n_{1}\lambda_{1}}{\lambda_{2}} = \frac{60 \times 4000}{6000} = 40$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.