Explanation:
Distance of \(n^{\text {th }}\) fringe from central fringe \(y = \frac{{nD\lambda }}{d}\,\,\,[{\rm{where }}n = 1,2, \ldots .]\)
Here, \(y = 5\;cm,n = 5,D = 1\;m,\lambda = 600\;nm\)
Let \(d\) is separation between the slits.
\(5 \times {10^{ - 2}} = \frac{{5 \times 1 \times 600 \times {{10}^{ - 9}}}}{d}\)
\( \Rightarrow d = 60\mu m\) (using (1))