Question

The force between an alpha-particle and an electron separated by a distance of 1A is

Answer 1

Here, charge of alpha particle = +2 Coulomb,

         charge of electron          = -1 Coulomb,

         distance between them = 1 Armstrong = 10^-10 m,

    we know from coulomb's law,

                       F = k(q1*q2)/d^2        k= constant = 9*10^9 Nm^2/C^2

                          = [ (9*10^9) * 2 * (-1) ] / (10^-10)^2

                         = -1.8*10^30 N

      here (-) sign signifies that the force is attractive as the charges are opposite.