In Young's double slit experiment the separation d between the slits is 2 mm, the wavelength λ of the light used is 5896 and distance D between the…

In Young's double slit experiment the separation d between the slits is $\displaystyle 2$ mm, the wavelength $\displaystyle \lambda$ of the light used is $\displaystyle 5896 \AA$ and distance D between the screen and slits is $\displaystyle 100$ cm. It is found that the angular width of the fringes is $\displaystyle 0.20^{\circ}$. To increase the fringe angular width to $\displaystyle 0.21^{\circ}$ (with same $\displaystyle \lambda$ and D) the separation between the slits needs to be changed to