Question

Calculate the Coulomb force between them at this separation.

Answer 1

The average separation between proton and electron of Hydrogen is $r=5.3{10}^{-11}m$.
Coulomb's force $=F=9\times {10}^9\times \frac{q_1{q}_2}{r^2}=\frac{9\times {10}^9\times (1.0\times {10}^{-19}{)}^2}{(5.3\times {10}^{-11}{)}^2}=8.2\times {10}^{-8}N$.