The charge of the copper nucleus is 29 times the charge of one proton:
the charge of the electron is
and their separation is
The magnitude of the electrostatic force between them is given by:
where
is the Coulomb's constant. If we substitute the numbers, we find (we can ignore the negative sign of the electron charge, since we are interested only in the magnitude of the force)
the charge of the electron is
and their separation is
The magnitude of the electrostatic force between them is given by:
where