The ratio of electrostatic force to the gravitational force between an electron and a proton separated by a distance r from each other is $\frac{F_{\text{elec}}}{F_{\text{grav}}}$ = $\frac{\frac{Ke.}{r^2}}{\frac{G m_e m_p}{r^2}}$ = $\frac{Ke^2}{G m_e m_p}$ In terms of dimensions So, $\left[ \frac{Ke^2}{G m_e m_p} \right]$ = $\left[ \frac{F_{\text{elec}}}{F_{\text{grav}}} \right]$ = $\frac{M L T^{-2}}{M L T^{-2}}$ = 1 Thus, the ratio $\frac{Ke^2}{G m_e m_p}$ is dimensionless $\frac{Ke^2}{G m_e m_p}$ = = 0.23 × $10^{40}$ = 2.3 × $10^{39}$ This ratio signifies that electrostatic forces are $10^{39}$ times stronger than gravitational forces