For the calculation of wavelength of spectral lines Rydberg gave a formula and use a constant called Rydberg's constant.Formula\\\\(\\rightarrow \\dfrac{1}{\\lambda}=RZ^2\\left(\\dfrac{1}{n_2^2}-\\dfrac{1}{n_1^2}\\right)\\\\)where \\\\(\\lambda=\\\\) wavelength\\\\(R=\\\\) Rydberg's constant\\\\(Z=\\\\) atomic number of atom\\\\(n_1\\ \\&\\ n_2=\\\\) Integers The value of Rydberg's constant is \\\\(1.0973\ imes10^{7}\\ m^{-1}\\\\)