By Andrew Youngker
Updated Mar 24, 2022
Nearly everyone has tried to make two refrigerator magnets touch each other. If the magnets have the same pole exposed, they resist contact. Opposite magnetic poles attract, while similar poles repel. This behavior is governed by the magnetic field that surrounds each magnet.
Magnetic fields are produced by electric currents—whether in wires or moving electrons. The interplay of electricity and magnetism underpins devices such as electric generators. In long magnets like a compass, the field lines emerge from the north pole and enter the south pole, creating a clear bipolar pattern.
When a magnet is electrically induced, it develops a north and a south pole. Like poles repel because their field lines exit the same side; opposite poles attract because the lines flow from one to the other. Thus, two north ends pushing against each other create a repelling force that grows stronger as the magnets are brought closer.
There are two main categories: permanent magnets, such as bar magnets whose atomic domains remain aligned, and electromagnets, where a current through a coil creates a magnetic field that can be switched on and off. Even a plain iron bar can become a magnet when its electrons are forced into a particular alignment.
The Earth itself is a giant magnet, generated by convection currents in its molten iron core. Although the surface feels only a weak field, it protects life by trapping charged particles from the Sun. The magnetic south pole actually lies near the geographic North Pole, and the magnetic north pole near the geographic South Pole, which is a common source of confusion.
Understanding these fundamentals explains why like poles repel and how we harness magnetic forces in everyday technology.
