Introduction to Molecular current hypothesis
Ampere believes that there is a ring current inside the molecules that make up the magnet-molecular current. Due to the existence of molecular current, each magnetic molecule becomes a small magnet, which is equivalent to two magnetic poles on both sides. Generally, the molecular current orientation of magnet molecules is disordered, and the magnetic fields generated by them cancel each other out and are not magnetically visible. When the external magnetic field acts, the orientation of the molecular current is approximately the same, and the two ends show a strong magnet action, forming a magnetic pole, which is magnetized. When the magnet is subjected to high temperature or violent impact, it loses its magnetism because of the violent thermal movement or vibration that makes the orientation of the molecular current become disordered.