How does an object go from having a neutral charge to having an over all negative or positive charge?
Friction is applied and those busy electrons jump from one object to the other...eg. your hair and your comb. When you start to apply friction (comb your hair) they each have a neutral charge, but friction charges the electrons up and makes them jump..creating, say, an overall negative charge in your hair and and an overall positive charge in the comb. Because there are too many LIKE charged particles in your hair, the strands repel each other. The comb can be hovered over paper and it will attract the opposite charges in the neutral paper. Get it?
The particles then discharge and return to their neutral state which is why you have to keep on charging up the comb!!
Watch these two clips to help you understand more. If you hear anything new...remember to add it to your notes.