Two identically charged particles separated by a distance of

Two identically charged particles separated by a distance of 3.7 m repel each other with a force of 4 N. What is the magnitude of the charges 7.8e-05 C 7.9e-05 C 7.7e-05 C 7.6e-05 C

Solution

Electrostatic force between two charged particles is

            F = k q ² / r ²

            q ² = F r ² / k

                 = ( 4 N ) ( 3.7 m )² / ( 9x 10⁹ Nm² / C² )

             q = 7.8x10^-5 C