Slide 8 of 11
Notes:
Notice the similarity with Newton’s Law of gravity. The big difference is that gravity always attracts (as the saying “gravity sucks” reminds us), while electrical force between charges of the same sign is repulsive; it is attractive if the charges are of opposite sign (like the older saying “opposites attract”). Otherwise, like gravity, Coulomb’s Law is an inverse square law, and the force direction is “along the line of centers” between the charged objects.
