Electromagnetism, one of the physical concepts, is the general term for the electrical and magnetic properties of matter. Such as electromagnetic induction, electromagnetic wave, etc. Danish scientist Oster discovered electromagnetism. Electromagnetic phenomena is caused by the fluctuation of charge movement and the formation of magnetic field, so all electromagnetic phenomena can't do without magnetic field. Electromagnetism is a branch of physics, which studies the interaction, law and application of electromagnetism. Maxwell's hypothesis of changing electric field to produce magnetic field laid the whole theoretical system of electromagnetism, developed electrical and electronic technology that had a great influence on modern civilization, and profoundly influenced people's thinking of understanding the material world.

Electromagnetism is the reaction of energy, and it is the general name of electrical and magnetic properties of matter.

Such as electromagnetic induction, electromagnetic waves, electromagnetic fields and so on. All electromagnetic phenomena is inseparable from the magnetic field; Magnetic fields are generated by moving charges.

The moving charge will fluctuate. The fluctuation mechanism is as follows: the moving charge E must be hindered by its neighbor E, which shows that the moving charge drives its neighbor 1 to move upward, that is, the neighbor moves upward with the moving charge E; When the adjacent 1 moves upward, it is bound to be hindered by its own adjacent 1, which means that the adjacent 1 drives its own adjacent upward movement, that is, the adjacent 2 moves upward together with the adjacent 1. This spread forward, forming fluctuations. Obviously, the propagation speed of this wave in a vacuum is the speed of light.