The function of the iron core in the coil

Coil and iron core or magnetic core function is to increase the strength of the magnetic field, the iron core can put the magnetic field line around the coil are concentrated from the flow of the iron core without the iron core, the magnetic induction between the coils will be small magnetic circuit and the circuit always find the reluctance (resistance) small place to go the iron core is much smaller than the air reluctance, so the magnetic flux from the iron core When the iron core is inserted inside the energized solenoid, the iron core is magnetized by the magnetic field of the energized solenoid, and the iron core becomes a magnet. In this way, because the two magnetic fields superimpose each other, the magnetic properties of the solenoid are greatly enhanced. In order to make the magnetic properties of the electromagnet stronger, the iron core is usually made into a hoof shape But we should pay attention to the hoof iron core coil around the opposite, one side clockwise, the other side must be counterclockwise if around the same, the magnetization of the two coils on the iron core will cancel each other, so that the core does not show magnetic electromagnet of the iron core made of soft iron and can not be made of steel Otherwise, once the steel is magnetized, it will remain magnetic for a long time and cannot demagnetize, and the strength of its magnetism can not be controlled by the size of the current, resulting in uncontrollable electromagnet magnetism.