${\mkern 1mu} \bar v{\mkern 1mu}  = {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} \frac{1}{\lambda }{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu}  \Rightarrow {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} \bar v{\mkern 1mu} {\mkern 1mu} {\mkern 1mu}  = {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} \frac{1}{{5800\,\mathop A\limits^o }}{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu}  \Rightarrow {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} \bar v{\mkern 1mu} {\mkern 1mu} {\mkern 1mu}  = {\mkern 1mu} {\mkern 1mu} \frac{1}{{5800{\mkern 1mu}  \times {\mkern 1mu} {{10}^{ - 8}}{\mkern 1mu} cm}}{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} ({\mkern 1mu} {\mkern 1mu} \because {\mkern 1mu} {\mkern 1mu} 1{\mkern 1mu} \mathop A\limits^o {\mkern 1mu} {\mkern 1mu}  = {\mkern 1mu} {\mkern 1mu} {10^{ - 8}}{\mkern 1mu} cm)$

$\begin{gathered}
   \Rightarrow \,\,\frac{{{{10}^8}}}{{5800\,\,}}\,c{m^{ - 1}}\,\,\, \Rightarrow \,\,17241.44\,\,c{m^{ - 1}} \hfill \\
  v\,\, = \,\,c\bar v\,\,\,\,\, \Rightarrow \,\,\,\,3\, \times \,{10^{10}}\,cm\,{s^{ - 1}}\,\, \times \,\,\,1.7\, \times \,{10^4}\,c{m^{ - 1}}\,\,\, = \,\,3\,\, \times \,\,1.7\, \times \,{10^{14}}\,\,\, = \,\,\,5.1\, \times \,{10^{14}}\,{s^{ - 1}} \hfill \\ 
\end{gathered} $