\(\frac{1}{\lambda }\,\, = \,\,R\,\,\left[ {\frac{1}{{{1^2}}} - \frac{1}{{{n^2}}}} \right]\,\,\)
\(\therefore\) \(\frac{1}{{975\,\, \times \,\,{{10}^{ - 10}}}}\,\, = \,\,\,1.1\,\, \times \,\,{10^7}\,\left[ {\frac{1}{{{1^2}}} - \frac{1}{{{n^2}}}} \right]\) અથવા
\(n\,\, = \,\,4\)