In atomic physics, The Rydberg formula is used to describe the wavelengths of spectral lines of many chemical elements.
The modified Rydberg formula given below is used for hydrogen element.
λvac = the wavelength of the light emitted in vacuum;
R = the Rydberg constant for this element;
n1 and n2 = integers such that n1< n2, corresponding to the principal quantum numbers of the orbitals occupied before and after.