Question

Q. In Young's double slit experiment , separation between two coherent sources is 0.90 mm and fringes are formed at a distance 1 m from the slits . If the second dark fringe is formed at a distance 1mm from the central band, then determine the wavelength of the monochromatic light used.

Answer 1

Dear Student,

$$\begin{gathered} d=0.9mm,D=1m,y=1+1=2mm \\ y=\frac{3D\lambda }{2d} \\ 0.002=\frac{3*1*\lambda }{2*0.0009} \\ \lambda =1200nm. \\ Regards \end{gathered}$$