One of the basic components of electronic devices and machines, electromagnets are used in various applications and fields like scientific research, home appliances, industrial manufacturing of products, gadgets and gizmos, chemical factories, etc. This ScienceStruck post provides you with a brief idea about electromagnets, especially regarding their working mechanism.
Do you know what is unique about electromagnetic waves? They are the only type of waves that can travel through empty space.
The first physicist to study the phenomenon of electromagnetism was Hans Christian Ørsted in the early 19th century. This discovery was possible when in his laboratory, a wire carrying electric current started to affect a compass present nearby. Ørsted thought that by some manner, a magnetic field is being generated by the wire, which was affecting the stability of the compass needle.
Observation: The needle of the compass deflected from magnetic north and returned to point north when the current through the wire was cut.
In the later years, another physicist called James Maxwell started to study the relation between positive and negative charges of electricity, and he discovered that a magnet consists of two oppositely charged poles. He also observed that when a conducting medium like a wire carries an electric current, a magnetic field is developed around it.
To gain information about the working mechanism of these devices, it is essential to know the basics of several parameters related to the generation of magnetic field. Such aspects have been briefly discussed below, and will help you to understand the working of an electromagnet.
➦ What is a Solenoid: A coil formed by numerous tightly wound turns of insulated copper wire is basically known as a solenoid, and it is one of the most fundamental parts of an electromagnet. This wire is coiled around a material known as the core of the electromagnet, and using an iron rod is the best option for making this part.
➦ As a magnetic field: When an electric current is passed through the solenoid, a magnetic field is generated. Just like a bar magnet, a solenoid also consists of the North pole and South pole at its opposite ends. If it is suspended in air, it will show an alignment along the true North and South pole of the Earth. The strength of the magnetic field produced by the solenoid depends on factors like the current intensity, and the number of times the wire has been wound around the core material. If the wire turns are higher in number, then the magnetic field will start adding up along the length of the core, and coupled up with a high strength of the current, a very strong electromagnet can be made. The conducting level of the material also plays an important role in the functioning of an electromagnet, and in scientific terms, it is known as magnetic permeability. Solenoid valves are a very good example of this component, wherein they are used in numerous hydraulic and automotive features.
Magnetic Domains and The Principle
In any material, the atoms are arranged or oriented in a random manner in specific regions called domains, and they vibrate or move along numerous directions, depending on their type. According to the arrangement, the materials are categorized as:
- Diamagnetic substances
For making an electromagnet, ferromagnetic and ferrimagnetic materials are mostly used, as the magnetic field produced by these substances is strong enough to be used for industrial applications.
Principle: When an electric current is passed through these materials, the atoms that were previously arranged in a random manner get oriented in a single direction, i.e., along the direction of the electric current, and form a magnetic field in their surrounding area. This is the basic principle on which the working mechanism of electromagnets is based upon.
The alignment depends on several factors like the value of the electric current in amperes, the number of coils of the solenoid, the type of material used, etc. Soft iron rods, mainly opted as the Fe atoms, get aligned in a proper manner, and after the current is switched off, the original directions are attained, i.e., the magnetic field is stopped from being produced. The magnetic field strength can also be controlled by managing the level of current that is passed through the core material.
After understanding the above-described parameters, the working of an electromagnet is described as follows:
- On application of an electric current, the particles of the ferromagnetic element get charged and begin to move or align themselves along the direction of the current.
- The path taken by the particles for traveling creates a field of magnetism around the region traced by it, and the resultant magnetic field vibrates in a direction that is perpendicular to the direction of the electric field.
- The strength of this magnetic field depends on the flow of the current, which can be altered (increased or decreased) by changing the direction of the current flow.
- The charged particles always move in tandem with the magnetic field. Thus, an electromagnet is created by the flow of an electric current.
- The field or the area of influence depends on the strength of the magnetic field, which is directly related to the cross-sectional area of the conductor, the rate of the flow of the current, and the change in direction of its flow.
The electromagnetic field generated is present around the core material that forms the device. Basically there are two types of conductors:
Straight rod-like: Here, the electromagnetic field appears in the form of concentric circles and is present on the conductors.
Circular coil-like: In this type, the lines of the electromagnetic field are concentric or circular near the wire and become straight or parallel near the central portions of the coil. Thus, the strength of the field lines combine at these central portions, and the resultant field is stronger than the one produced by straight conductors.
Electromagnets that are used in household appliances (like TV remotes, toy cars, electric trimmers, electric egg beaters, etc.) make the use of AA or even AAA batteries, in order to work. Other appliances like mixers, juicers, iron, refrigerators, etc., use the supply of Alternating Current (AC).
Electromagnets used in heavy machinery that is utilized in factories, industries, iron scrap metal dumps, junkyards, and also in scientific research derive power from generators or some other external source of electricity for their working.
Everyday life has a range of examples that rely largely on the use of electromagnets.
- The best and most formidable ones that showcase the working mechanism of these devices is the irrigation process utilized in agricultural fields and/or in modern plumbing applications. It involves a complex arrangement of these motors to supply water in the most cramped or difficult places.
- Cranes used in construction industry and various other jobs involving the application and movement of heavy equipment, electromagnetic generators, etc., are prime examples of these devices.
- Microwaves, electric motors, computers, etc., are some of the most common areas where the application of electromagnetic energy is growing continuously.
- Another recent and rapidly developing area is in the electromagnetic spectrum. The use of modern communication systems, such as mobile phones and other wireless connectivity applications, have made enormous progress in the field of electromagnetism.
- Do you know how a Maglev train zooms away so fast, in spite of hardly being in contact with any material on its bottom side? This technology works due the application of electromagnets, wherein the trains levitate above the tracks, making it possible for them to move at high speeds. This type of magnet is created when electricity is passed through a conducting medium that can include ferromagnetic materials like iron, cobalt, and nickel. These mediums are wrapped up by many coils of wire. The electric current starts to induce a magnetic field in the ferromagnetic core of the material.
Working of an Electromagnet in a Doorbell
Ever wondered how a doorbell makes a continuous ding-dong or buzzing noise when you press the switch button? The diagram and the following paragraph will explain the working procedure of this example.
A doorbell makes perfect use of the application of electromagnets, and the ever-improving technology has resulted in many varieties being innovated. In a simple design, the doorbell box consists of a bell, a transformer, clapper, metal arm, and an electromagnet. The electric current is passed through the transformer and enters the metal arm that is in contact with the clapper. An electromagnet is placed below this assembly. Now, as the button is switched on, the clapper is attracted towards the magnet; hence, it rings the bell, thereby, breaking the circuit. Now, a metal contact again pulls back the arm, thus, completing the circuit. This process is repeated till the person is pressing the switch button. The accompanying diagram will help you understand the working in a clear manner.
Application Using Electromagnetic Spectrum
Electromagnetic spectrum is nothing but a group of frequencies that are categorized according to the frequency ranges they occupy, and exhibit certain uses on account of these ranges known as a spectrum. Visible light emanating from a bulb, the X-rays that mostly find application in medical procedures, or the radio waves that corresponding to a radio station are components of this spectrum. Thus, all frequencies of electromagnetic radiation are included in the electromagnetic spectrum.
Different components react differently with matter; hence, they produce a wide range of applications. For example:
- Radio waves stimulate oscillation of charge carriers.
- Ultraviolet rays produce an excitation in molecular electrons and the valence electrons.
- X-rays cause excitation of core atomic structures.
These effects impart different properties to the components of electromagnetic spectrum.
Thus, electromagnetism forms an integral part of many human activities, and the related applications are a big asset to the progress of humanity.