Rub a balloon containing a few pieces of Styrofoam towards your sweater or a piece of wool/fur. What do you observe when you touch with your finger one of the piece through the balloon? Why does this happen? The Styrofoam repels within the balloon. You charge the balloon negative by rubbing it against your sweater and the electrons of the neutral Styrofoam are pushed as far as possible from the walls of the balloon making the side of the Styrofoam touching the balloon positive. When you put your finger on where the Styrofoam is touching the balloon, you are grounding the electrons on the surface of the balloon into your hand and making that spot on the balloon positively charged. Since the side of the Styrofoam touching the balloon is charged positive and you've made that spot positive, the Styrofoam repels. Am I on the right track or just talking crap?