# What is the suction of a magnet?

## What is the suction of a magnet?

The attraction of magnet belongs to electromagnetic force. Electromagnetic force is one of the four forces discovered so far by human beings. It is the most thoroughly studied and the most common force in daily life.
When people see that two magnets can attract each other, they directly think of gravity and think that it is the action of gravity, which is totally wrong. The essence of gravity is the distortion of space-time by mass, which is much weaker than electromagnetic force; and the essence of electromagnetic force is the electric charge between objects, which is the force field generated by the interaction between charged particles and electromagnetic field.
Almost all the force phenomena we see in our daily life are electromagnetic force. Such as electricity, friction, elastic force, mechanical force, etc., sound wave is also a kind of mechanical wave, so it also belongs to the performance of electromagnetic force.
Due to the special internal structure of its atoms, magnets have magnetic moment, produce magnetic field, and can carry out electromagnetic conversion. Therefore, mutual attraction of magnets is also an expression of electromagnetic force.
The movement of cars, trains, planes, people and ants can not be separated from the category of elastic force, mechanical force, friction force and electric power, so they are all electromagnetic forces.
The transmission medium of electromagnetic force is photon.
These photons transfer energy through electromagnetic field. The way of transfer is electromagnetic wave, which has wave particle duality. It is the same and mutually perpendicular electric field and magnetic field derived from the emission of oscillatory particle wave in space. It is the electromagnetic field in the form of wave propagation.
Electromagnetic interaction force is the second strong force among the four forces. If the strength of strong interaction force is 1, then the strength of electromagnetic interaction force is 1 / 137, the strength of weak force is 10 ^ – 13, and the strength of gravity is 10 ^ – 39.
It can be seen that gravity is the weakest force, which is hundreds of millions of times different from the strength of strong force and electromagnetic force.
However, both gravity and electromagnetic force are long-range forces with the longest acting distance, which are theoretically infinite and inversely proportional to the distance. Another common point of these two forces is that they are mainly reflected in the macro, gravity is more reflected in the celestial body movement, and electromagnetic force is reflected in various phenomena that can be seen by human beings.
The strong and weak forces are shown in the microscopic world that we can’t see at ordinary times. The strong forces mainly act between neutrons and protons, and the weak forces only act on quarks, electrons, neutrinos, etc.
The transmission media of these forces are only electromagnetic force, strong force and weak force.
As mentioned above, electromagnetic force is transmitted by light quantum, but you should not misunderstand that light quantum will emit light. Light has visible light and invisible light. Invisible light is transmitted in the form of radio waves, microwave, infrared, visible light, ultraviolet, X-ray and gamma ray. The medium for transmitting strong force is gluon, and the medium for transmitting weak force is fermion or boson.
The transmission medium of gravity has not been determined yet. Quantum mechanics thinks that gravity is transmitted by graviton, but it is only a conjecture. No direct or indirect proof of graviton has been found.
At present, all phenomena discovered by human beings belong to the category of these four basic forces, and electromagnetic force is the most thoroughly studied force. Its law has been explained in Maxwell equations and Lorentz force formula for a long time.

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