Electric Charge Basics

Rub a balloon on your hair and it sticks to the wall. No glue. No magnets. Just electrons, a trillion trillion of them, relocated from hair to rubber. That invisible tug holding the balloon in place is the same force that moves electricity through a power grid.

Charge is a fundamental property of matter, like mass. Every proton carries one positive charge; every electron carries one negative charge. Normally atoms are electrically neutral, with equal counts of each. When that balance is disturbed, charges pile up and a force emerges.

The rule is simple: like charges repel, opposite charges attract. Two negatives push apart. One negative and one positive pull together.

What makes charge different from, say, friction is how sharply the force scales with distance. Coulomb's Law says the force between two charges falls off as the square of the distance: double the distance, the force drops to one-quarter. This is the same inverse-square pattern as gravity, but electrostatic forces between subatomic particles are roughly 10³⁶ times stronger.

Worked Example

Two small charged spheres sit 1 cm apart, and you measure a repulsive force of 4 newtons.

If you move them to 2 cm apart, what do you expect the force to become?

Distance doubled, so distance² quadrupled, so force divided by 4. The new force is 1 newton. The charges didn't change; only the spacing did.

Charge is the foundation of everything electrical: current, voltage, capacitors, batteries. Understanding how charges interact at close range is the prerequisite for understanding why moving them through a wire or separating them across a battery requires work and stores energy.

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