Video narration
Why does walking across a carpet sometimes end with a tiny shock when you touch a doorknob? That jolt is not a blob of electricity stored inside you. It is evidence that matter has a property called electric charge. Charge is not a visible fluid or separate substance. It tells you how strongly matter participates in electric forces-how it can push or pull. Rubbing and walking redistribute charge between you, your clothes, and the floor. That imbalance creates forces. Charge comes in two signs: positive and negative. Like charges repel; unlike charges attract. A charged balloon can pull on nearby material; similarly charged objects push apart. Charge is measured in coulombs, the standard unit. When you touch the knob, charge briefly moves between objects, producing the shock. Charge is the measurable property that determines how matter responds to electric forces: positive or negative, measured in coulombs.