Question

A red line is observed at 656.3 nm in the spectrum of atomic hydrogen. Determine the values of n for the beginning (n1) and ending (n2) energy levels of the electron during the emission of energy that leads to this spectral line.

Answer 1

From Rydburg's Equation , 1/ λ = R[(1/n_i²) – (1/n_f²)]
   Where R = Rydburg's constant = 10.96 x10⁶ m^-1
               λ = wavelength = 656.3 nm = 656.3x10^-9 m
               n_i = ?
               n_f = ?
Plug the values we get

[(1/n_i²) – (1/n_f²)] = 1/ (λR)

= 0.139

It is possible only when n₁ = 2 & n₂ = 3