Electromagnet (solenoid) is a device that generates electromagnetism when it is electrified. In the core of the external winding and its power to match the conductive winding, the current of the coil like a magnet, it is also called electromagnet. Electromagnet is widely used in our daily life. Because of its invention, the power of generator has been greatly improved.

When the iron core is inserted into the solenoid, the iron core is magnetized by the magnetic field of the solenoid. The magnetized iron core also becomes a magnet, so the magnetic field of the solenoid is greatly enhanced due to the superposition of the two magnetic fields. In order to make the electromagnet more magnetic, the iron core is usually made into a shoe shape. However, it should be noted that the winding direction on the hoof core is opposite, one side must be clockwise, the other side must be counterclockwise. If the winding direction is the same, the magnetization of the two coils to the iron core will cancel each other, so that the iron core will not show magnetism. In addition, the iron core of electromagnet is made of soft iron, not steel. Otherwise, once the steel is magnetized, it will remain magnetic for a long time and can not be demagnetized, so the strength of its magnetism can not be controlled by the size of the current, and it will lose the advantages of electromagnet.

Electromagnet is a kind of device that can generate magnetic force through current. It is a non permanent magnet and can easily start or eliminate its magnetism.

Classification of electromagnets:

Electromagnets can be divided into two types according to current

(1) DC electromagnet

(2) AC electromagnet

Electromagnets can be divided into the following five types according to their uses:

(1) Electromagnet (solenoid) - it is mainly used to pull mechanical devices, open or close various valves to perform automatic control tasks.

(2) Electromagnet (solenoid) - used as a lifting device to lift ferromagnetic materials such as ingot, steel, iron sand, etc.

(3) Electromagnet (solenoid) - mainly used to brake the motor to achieve the purpose of accurate parking.

(4) Electromagnet (solenoid) - such as electromagnetic system of electromagnetic relay and contactor, electromagnetic release of automatic switch and operating electromagnet, etc.

(5) Electromagnets (solenoids) for other purposes, such as the electromagnetic chuck of grinder and electromagnetic vibrator.