Diagram to show how the inverse square law works.

How an inverse square law force works.

The gravitational force and the electrostatic force are both inverse square law forces. What does this mean? Both the gravitational force and the electrostatic force decrease to 1/4 in magnitude if the particles are twice as far apart and 1/9 if they are three times further apart. The magnitude of the the force is inversely proportional to the square of the distance between the interacting point masses or charges.

Even though the underlying nature of gravitational and electric force are very different, the mathematical formulas describing the interactions in classical physics are very similar. Of course there are also differences. For example, while gravity has only been observed as a force of attraction, the electrostatic force can either attract or repel, depending on whether there are like or unlike charges involved. Furthermore, the electric force has its flip-side, magnetism. No magnetism like analogy for gravitation has yet been observed.