\({n_1}\,{\lambda _1}\,\, = \,\,{n_2}\,{\lambda _2}\,\, \Rightarrow \,\,\,\frac{{{n_1}}}{{{n_2}}}\,\, = \,\,\,\frac{{{\lambda _2}}}{{{\lambda _1}}}\,\, = \,\,\,\frac{{5200\,\mathop A\limits^ \circ  }}{{6500\,\,\mathop A\limits^ \circ  }}\,\, = \,\,\,\frac{4}{5}\)

\(n\)આને \({n_2} \) ની ન્યૂનતમકિમત માટે \({n_1} = \,\,4\,,\,\,{n_2} = \,\,5\)

તેથી \(x\,\, = \,\,\,\frac{{{n_1}\,{\lambda _1}D}}{d}\,\, = \,\,\frac{{4\,\, \times \,6500\,\, \times \,\,{{10}^{ - 10}} \times \,\,120\,\,\, \times \,\,{{10}^{ - 2}}\,}}{{2\,\, \times \,\,{{10}^{ - 3}}}}\,\) 

\( = \,\,\,0.156\,\, \times \,\,{10^{ - 2}}\,m\,\, = \,\,0.156\,\,cm\)