Electrostatics

In hydrogen atom an electron revolves around a proton (in nucleus) at a distance 'r' m. the intensity of electric field due to the proton at distance 'r' is \(5 \times 10^{11} \mathrm{NC}^{-1}\), the magnitude of force between the electron and proton is [charge on electron \(=1.6 \times 10^{-19} \mathrm{C}\)]