Electric charge is a property of matter that makes it feel a force when it is in an electric field. Think of it as a tiny invisible magnet that can attract or repel other similar magnets. There are two types of charge: positive (+) and negative (−).
Imagine a party where each guest has a small sticker that is either a plus or minus sign. Guests with the same stickers (both + or both −) push away from each other, while guests with opposite stickers (one +, one −) pull towards each other. This is exactly how electric charges interact.
The SI unit of electric charge is the coulomb (C). One coulomb is the amount of charge that flows past a point in a conductor when one ampere of current passes for one second.
Mathematically, \$Q = I \cdot t\$ where \$Q\$ is charge in coulombs, \$I\$ is current in amperes, and \$t\$ is time in seconds.
| Unit | Symbol | Description |
|---|---|---|
| Coulomb | C | SI unit of charge |
| Statcoulomb | statC | CGS unit of charge |
When you rub a balloon on your hair, electrons (negative charge) transfer from your hair to the balloon. The balloon now has a net negative charge. If you bring the balloon close to a small piece of paper, the paper will be attracted to the balloon because of the opposite charges.