Two point charges are separated by 6 cm. The attractive force between them is 20 N. Find the force between them when they are separated by 12 cm. (Why can you solve this problem without knowing the magnitudes of the charges?)

Answer 1

Use the inverse square rule. You have doubled the separation distance. Look at Coulomb's law and see what that does to the force.

Answer 2

i don't get it at all