Rub a balloon on a sweater or hair. Watch electrons move, then bring the balloon near a wall or paper bits.
| + charges | − charges | Net charge | |
|---|---|---|---|
| Balloon | |||
| Sweater |
Only electrons move. Protons stay in the nucleus. Net charge = number of + minus number of −. Opposite charges attract. Like charges repel.
Simplified model: each rub moves one electron. Real amounts are far larger.