Introduction to the principle of magnet attraction and repulsion, recommended collection
Introduction of Graphics and Texts of the Principle of Magnets'Phase Absorption and Repulsion
The magnets written in middle school physics books have S poles and N poles. If the S poles or N poles of two magnets are put together, there is repulsion between them. If one N pole and one S pole are put together, there is attraction between them.
The force attracting or repelling each other is the magnetic force, which is produced in the magnetic field. In order to explain the magnetic field, Faraday introduced the concept of magnetic induction line. The magnetic induction line is a closed curve which is artificially prescribed but actually does not exist. Inside the magnet, from S to N, and outside, from N to S. The magnetic induction line is attractive in the same direction and repulsive in the opposite direction. When there is a certain angle, the magnet tends to rotate in the same direction as the magnetic induction line. Generally speaking, magnetic induction lines do not exist objectively. They are only concepts introduced by people to study the force in magnetic field and electromagnetic induction phenomena.
Quantum electrodynamics considers that the essence of electromagnetic interaction force (isotropic repulsion, heterosexual attraction) is the result of the continuous exchange of photons between two particles. What happens when two electrons get close to each other and eventually bounce off because of electromagnetic forces? It turns out that the two electrons are constantly exchanging photons. Imagine two people on the skating rink, who keep throwing a ball around, throwing it from one person's hand to another, so that they must be farther and farther away, as if there was a repulsion between them. In the electromagnetic force, this ball is photon! So what about homosexual attraction? You can imagine two people standing back-to-back, throwing the ball on the wall facing each other and bouncing back into each other's hands, which seems to have a kind of attraction to keep them close together.
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