An electron with a kinetic energy of 3.90 ev collides with a sodium atom.

The wavelength transition line is

Δ = hc/Δ∈

=1240 e V. nm/3.75e V - 0,0ev

=330. nm

Another wavelength transisiton is

Δ = hc/Δ∈

1240e V. nm/3.19e V - 2.104e V

1140. nm

Some other wavelength transition are;

590, 816, 2180, 8860.