In daily life, people often put some beloved little things on the side of the refrigerator to decorate them. We all know that the reason these little things can be attached to the refrigerator is that it has magnets. In our experience, without any intervention, these magnets can be attached to the side of the refrigerator for so long that it can be said to be lost for decades.
Magnets are attached to the sides of the refrigerator. Earth's gravity pulls it down. Therefore, the magnet must have the energy against gravity. So where does its strength come from, let us first analyze the force state of the magnet. When the magnet shirt is attached to the side of the refrigerator, it is at rest. According to Newton's first law of motion, an object at rest experiences zero external force.
After a simple analysis, we can conclude that in this state, the magnetic system is subjected to four forces, which are the electromagnetic force between the magnet and the side of the refrigerator (this is two forces), the electromagnetic force and the friction on the side of the refrigerator force, so that these four forces are opposite to each other and equalize each other, so that the magnet is in a static state.
Therefore, we can conclude that "the phenomenon that the magnet sticks to the side of the refrigerator and does not fall off for decades" is a force equilibrium phenomenon, which leads to this reason.