Opposite magnetic poles pull toward each other, while matching poles push each other away.

The longer version

Magnetic field lines prefer the shortest, lowest-energy arrangement they can find. When opposite ends face each other the fields join smoothly, pulling the pieces together. When matching ends face each other the fields push against one another, so the pieces slide apart before any contact is made.

The force grows rapidly as the gap narrows, which is why the snap-together feels sudden. Nothing is consumed in the process, so the attraction or repulsion continues indefinitely. Heating a magnet or dropping it repeatedly can scramble the internal alignment and weaken both effects, and a freely turning compass needle simply swings until it lines up with the surrounding field.

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.