Question

Two spheres carrying charges +6μC and +9μC, separated by a distance d, experiences a force of repulsion F. When a charge of −3μC is given to both the sphere and kept at the same distance as before, the new force of repulsion is

Answer 1

$f = (k \times 54 \times 10^{ - 12}) \div d \\ \\ fnew = (k \times 18 \times 10^{ - 12}) \div d \\ \\ fnew = \: f \div 3$