Video narration
Why does a rubbed balloon pull toward something, while charged objects can push apart-and why can't charge have any value? The answer starts with signs. Like charges have the same signs and repel; unlike charges have opposite signs and attract. So signs tell you whether the interaction is a push or a pull. But here is the turn: charge is not continuous. It cannot have every amount. It comes in whole-number units of the elementary charge, e. That is what Q=ne means. Q is net charge, e is the magnitude of one elementary charge, and n is an integer-the number of units. n can be positive, negative, or zero. Keep the ideas separate: attraction and repulsion describe interaction; quantization describes which amounts are allowed. So the balloon's pull follows the sign rule; the charge follows counting: same signs repel, unlike signs attract, and Q=ne.