What is an electromagnet and how does it work?
Electromagnets produce a magnetic field. They are usually in the form of a coil, which is deposited on a core made of material with very high magnetic properties. As a result of the flow of electric current through the coil, a magnetic current is produced. It is this current that is responsible for magnetizing the core and amplifying it. The core is demagnetized when the current stops flowing. Then the electromagnet ceases to be the source of the magnetic field.
The electromagnet has the shape of a coil, in the middle there is a core made of ferromagnetics. It is usually made of steel, which is very good for magnetization. In the case of AC electromagnets, the core is made of metal sheets, which are isolated from each other by a special insulating material in order to reduce energy losses. In order to disperse the magnetic flux, electromagnets are often given a horseshoe shape.
The magnetic field produced by an electromagnet covers a similar area to that which is characteristic of a typical bar magnet. The field can be reinforced by winding a wire around an iron core. It must be 'soft', which means that it does not have the capacity to store a magnetic field. It is magnetized only after electric current has passed through it.
Use of electromagnets
With electromagnets, the magnetic field can be changed quickly. This is possible by controlling the amount of electric current in the winding. However, an electromagnet requires a constant current supply, only then can it maintain the magnetic field. Electromagnets are supplied with different voltages and thus consume different current. There are modules integrated with control electronics, which is an option especially recommended for beginners who plan to implement the electromagnet in an electronic system. The frequent use of electromagnets includes access control systems. We then use holding electromagnets which hold the door to prevent it from opening. And how do we open such doors? The electronic system receives an appropriate signal from the lock control system, which is a card reader or code keypad. The solenoid coil is de-energized, which means that it no longer attracts the metal plate to the door and can be successfully opened. Due to such properties of electromagnets they are used in access control systems.
Furthermore, they work well in many other electronic projects. They are present in electrical machines, bells, speakers and relays. Electromagnets are also used in alarm systems, which are one of the security features of the building and its surroundings, and are part of monitoring. They can also be found in cathode ray tubes and magnetic railways and devices that use nuclear magnetic resonance.