Quantum from series termination

Using the circular orbits of the Bohr model, the meaning of the subscripts in the quantum numbers riband n, now become obvious n, is the initial Bohr orbit (the one farther from the nucleus, or the excited state) and is the final Bohr orbit, as shown in Figure 3.18. The following values of correspond with the listed series n = I (Lyman), nf=l (Balmer), n = 3 (Paschen), n = 4 (Brackett), and rif=S (Pfund). Thus, for example, the first four lines for the Balmer series originate in the n, = 3, 4, 5, and 6 energy levels and terminate in the n = 2 level, as shown in Figure TI8. 

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