In daily life, we often put some cute small objects on the side of the refrigerator to decorate it. We all know that the reason why these small objects can be attached to the refrigerator is that they have a magnet in them. But why do magnets stick to refrigerators? What are the working principles of the refrigerator magnet?Let’s find out.
When the magnet is attached to the side of the refrigerator, the gravity of the earth will “pull it down”, so the magnet must have a force to overcome gravity, so where does its force to overcome gravity come from?
Let’s first analyze the stress state of the magnet. When the magnet is attached to the side of the refrigerator, it is in a static state. According to Newton’s First Law of Motion, the combined external force of an object at rest is zero.
After a simple analysis, we can conclude that in this state, the magnet receives four forces, namely the electromagnetic force between the magnet and the side of the refrigerator (these are two forces), the gravity of the earth, and the friction between the magnet and the side of the refrigerator.
Therefore, we can draw a conclusion that the phenomenon that a magnet will not fall off when attached to the side of the refrigerator is due to the balance of the forces. The reason for this phenomenon, in the final analysis, is the result of the interaction between gravity and electromagnetic force.
So where does the electromagnetic force of a magnet come from?
Here’s a brief explanation.
An atom consists of a nucleus with a positive charge and an electron with a negative charge. Inside the atom, the electrons constantly move around the nucleus and spin at the same time, because the moving charge will generate an electric current and also a magnetic field, so this movement of electrons will generate a magnetic field.
In most substances, due to the disordered movement of electrons, this magnetic effect produced by electrons will cancel each other out, so that they do not exhibit magnetism. However, there is a very strong interaction between the electrons of ferromagnetic substances-“exchange coupling“, which makes the magnetic field generated by them spontaneously unified in a small area. We call these small areas “magnetic domains“.
As can be seen from the above picture, for a ferromagnetic substance, it has many magnetic domains. In general, these magnetic domains will not be arranged in the same direction, so they will not show magnetism as a whole.
However, if we put a piece of ferromagnetic substance into a sufficiently strong magnetic field, then these magnetic domains will be drawn in the same direction under the action of an external force. In this case, the ferromagnetic substance is magnetized and becomes a magnet.
It should be pointed out that due to the extremely strong “exchange coupling” between the electrons of the ferromagnetic substance, after the magnetization of the ferromagnetic substance, even if the external magnetic field is removed, the internal magnetic domains will remain consistent, so that in the macro it shows magnetism.
According to quantum theory, the magnetic domain inside the magnet (permanent magnet) is the result of minimizing energy, which means that as long as there is no external force intervention, then the magnet will always have magnetism. This is why the magnet is attached to the side of the refrigerator and will not fall off for decades.
Thank you for reading our article and we hope it can help you find the answer to why do magnets stick to refrigerators. If you want to know more about the fridge magnets, we would like to recommend you to visit Stanford Magnets for more information.
Stanford Magnets is a leading magnet supplier across the world who has been involved in R&D, manufacturing, and sales of permanent magnets since the 1990s. It provides customers with high-quality rare earth permanent magnetic products such as neodymium magnets, and other non-rare earth permanent magnets at a very competitive price.