Basic Definition of Electromagnet
An electromagnet is a device that contains an iron core inside and uses a coil with an electric current to make it magnetic like a magnet. It is called an electromagnet. It is generally made into a bar or hoof shape, and the iron core must be made of soft iron or silicon steel that is very easy to magnetize and very easy to demagnetize. Such an electromagnet will be magnetic when it is energized, and it will disappear when the power is turned off. Iron is widely used in daily life, and the invention of electromagnets has also greatly enhanced the power of generators.
When the iron core is inserted inside the energized solenoid, the iron core is magnetized by the electromagnetic field of the energized solenoid. The magnetized iron core also becomes a magnet, so because the two electromagnetic fields are superimposed on each other, the magnetism of the solenoid is greatly enhanced. Therefore, the magnetism of the electromagnet is stronger, and the iron core is generally made into a hoof shape. However, it should be noted that the winding direction of the electromagnetic coil on the shoe-shaped iron core is opposite, one side must be clockwise, and the other side must be counterclockwise. If the winding directions are the same, the magnetization functions of the two coils to the iron core will cancel each other, so that the iron core cannot see the magnetism. On the other hand, the core of the electromagnet is made of soft iron, not steel. Otherwise, if the steel is magnetized, it will always remain magnetic and cannot be demagnetized, and the strength of its magnetism cannot be manipulated by the magnitude of the current, and the advantages of electromagnets will be lost.
The electromagnet is a component that can pass current to form a magnetic force. It is a non-permanent magnet, which can be turned on or removed very easily. For example: large and medium-sized cranes use electromagnets to lift waste vehicles.
When the amount of electric current passes through the wire, an electromagnetic field is formed around the wire. Using this feature, when the amount of current is passed through the solenoid, a uniform electromagnetic field will be created inside the solenoid. Assuming that a ferromagnetic substance is embedded in the center of the solenoid, the ferromagnetic substance will be magnetized and the electromagnetic field will be greatly enhanced.
Generally speaking, the electromagnetic field formed by the electromagnet is related to the amount of current, the number of coil turns and the ferromagnet in the center. When designing electromagnets, attention is paid to the distribution of coils and the selection of ferromagnets, and the magnitude of current is used to control the electromagnetic field. Because the raw material of the coil has resistance, which limits the size of the magnetic field that the electromagnet can generate, but with the discovery and application of superconductors, there will be opportunities to overcome the existing limitations.
According to the current classification, electromagnets can be divided into two types: DC electromagnets and AC electromagnets. If the electromagnets are divided according to their uses, they can be mainly divided into the following four types: (1) Traction electromagnets—the key is used to pull mechanical equipment, open or close various valves, and implement automatic control tasks. (2) Lifting electromagnets - used as lifting and hoisting devices to lift ferromagnetic materials such as steel ingots, stainless steel plates, and iron sand. (3) Braking electromagnet - suitable for braking the motor to achieve accurate parking. (4) Electromagnetic systems of automatic electrical appliances - such as electromagnetic systems of electromagnetic relays and contactors, electromagnetic induction trippers of automatic switches and operating electromagnets, etc. (5) Electromagnets for other purposes - such as electromagnetic chucks of milling machines and their electromagnetic vibrators.
