Static electricity builds up when two different materials rub together and trade electrons.

The longer version

Different materials hold on to their electrons with different strength. When two surfaces touch and separate, electrons can transfer from the one that grips them loosely to the one that grips them tightly. Both objects then carry an imbalance of charge, and because like charges repel, the imbalance tends to stay put.

Dry air helps the charge accumulate, since moisture normally leaks it away. The effect builds until something conductive offers a path, at which point the stored charge moves all at once. That sudden movement is what produces the familiar crackle and tiny spark, and smaller objects hold less charge before releasing it.

Where this entry sits

Everyday physics and chemistry hide small wonders in plain sight, from kitchen reactions to the light in the sky. These short facts explain matter, energy, electricity, magnets, sound, and the simple units we use to measure the world. The full list sits on the Science and Physics page, where every entry is listed in order.