Question

In a double slit experiment if 5th dark fringe is formed opposite to one of the slits the wavelength of light is

Answer 1

Dear Student ,
here in this case from the equation we can write that ,
$$\begin{gathered} x=\frac{D}{d}\left(2n-1\right)\frac{\lambda }{2} \\ \Rightarrow \lambda =\frac{2xd}{D\left(2n-1\right)} \\ Nowhere2x=d \\ So,\lambda =\frac{d\times d}{D\left[\left(2\times 5\right)-1\right]}=\frac{d^2}{9D}. \end{gathered}$$
Regards