H alpha corresponds to a wavelength of about 655 nm so, like most of the lines in this series, it is visible.
The formula underlying this phenomenon gives the wave number of H alpha. That formula may be derived rigorously by considering a transition to the second excited state with the Born-Oppenheimer approximation, or by invoking the Bohr model of the hydrogen atom, and involves the Rydberg constant. H alpha corresponds to a wavelength of about 655 nm so, like most of the lines in this series, it is visible. For ten points, name this set of hydrogen emission lines named for a Swiss mathematician, which correspond to transitions to the n = 2 state.
The formula underlying this phenomenon gives the wave number of H alpha.
Balmer series (or lines)