The A B C of atoms

by Bertrand Russell

be the (negative) charge on the electron and the (positive) charge on the nucleus.

Then according to elementary dynamics, the centrifugal force of the electron in its orbit is

while the force attracting it to the nucleus is

by Coulomb’s Law. These two must be equal, so that

So far, we have been proceeding on traditional lines. But we come now to the application of the quantum theory.

The kinetic energy of the electron is