$\therefore \,\,\frac{1}{\lambda }\,\, = \,\,1.907\, \times \,{10^{ - 7}}\,\left( {\frac{1}{{{1^2}}}\, - \,\frac{1}{{{\alpha ^2}}}} \right)\,\,\,$
$\therefore \,\,\lambda \,\, = \,\,\frac{1}{{1.097\, \times \,{{10}^7}}}$$ = \,\,0.91\, \times \,{10^-7}\,\,\, = \,\,91\,\, \times \,{10^{ - 9}}\,\, = \,\,91\,\,nm$