Rub a balloon on your hair and it sticks to a wall. The rubbing transfers electrons from your hair to the balloon, giving the balloon a net negative charge. The wall has a positive charge, and opposite charges attract. Electric charge is a fundamental property of matter, like mass. It comes in two types, positive and negative. Like charges repel. Opposite charges attract. The force between them follows Coulomb's law, which says the force is proportional to the product of the charges and inversely proportional to the square of the distance between them.

Charge is quantized. It comes in discrete units, the smallest being the charge of a single electron, about 1.6 × 10⁻¹⁹ coulombs. Protons carry the same amount of charge but positive. Neutrons carry no charge. Charge is conserved. You cannot create or destroy it, only move it from one place to another. That is why rubbing a balloon does not create charge. It separates charge that was already there. Electric charge is the source of electric fields, and moving charge produces magnetic fields. Together, they form the electromagnetic force, one of the four fundamental forces of nature.

Charge facts

• Two types. Positive and negative.
• Like charges. Repel each other.
• Opposite charges. Attract each other.
• Quantized. Comes in units of electron charge.
• Conserved. Cannot be created or destroyed.

Charge is not the same as current. Charge is a property of matter. Current is the flow of charge.