Must more sophisticated moethods were developed when led to a determination of how the force relates to the amount of charge. In this law, the distance betweent he objects is labelled r. We see that this is an example of an inverse square law , meaning that the depence of the force in inverse to the sqaure of the distance between the objects. This is very much like the force law for graviatation discovered by Newton. One of the most significance differences between the Coulomb's law and Newton's law of gravity is that gravitation forces are always attractive.
Charges come in two varieities, positive and negative, and so charges can attracte or repel.
Scientists wonder what change in our understanding of Nature would be required if we ever discovered negative mass.