The A B C of atoms

by Bertrand Russell

. Since

is a

of a second (when

is the frequency), it follows that the energy of the wave is

. Also, by the principle of the conservation of energy, the energy of the wave is equal to the energy that the atom has lost.

This shows that, if e is the kinetic energy of the electron in the smallest orbit, the wave caused by a transition from the second orbit to the first will have a frequency