Using a commercially available hydrogen–deuterium light source and a 3.4‐m Ebert plane grating spectrograph, the wavelengths of the first six pairs of the Balmer series are obtained. From the results, first, the series limit, Rydberg constant, and ionization potential of hydrogen are found from the graph. Then, by means of formulas involving wave numbers of hydrogen and deuterium and by knowing the Faraday constant, the values of m, e/m, and Mp/m are determined. All the values are found to be in good agreement with accepted values. From the results, this experiment is recommended for an upper division optics and spectroscopy or quantum physics laboratory.