\(\frac{1}{\lambda}=R z^{2}\left(\frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}}\right)\) where \(R=\frac{1.097 \times 10^{7}}{1+\frac{m}{M}}\)

where \(\mathrm{m}=\) mass of electron

\(\mathrm{M}=\) mass of nucleus

For different \(M, \mathrm{R}\) is \(d \Leftrightarrow\) erent and \(\therefore\) lambda is different