Meaning of Electromagnetism (What it is, Concept and Definition)

What is Electromagnetism:

Electromagnetism is the study of charges and the interaction between electricity and magnetism. Electricity and magnetism are aspects of a single physical phenomenon closely linked by the movement and attraction of charges in matter.

The branch of physics that studies the interaction between electrical and magnetic phenomena is also known as electromagnetism.

The word “electricity” was proposed by the Englishman William Gilbert (1544-1603) from the Greek elektron (a type of amber that attracts objects when rubbed with various substances). On the other hand, “magnetism” probably arose from a Turkish region with deposits of magnetized magnetite (Magnesia), where an ancient Greek tribe known as the Magnetes lived.

However, it was not until 1820 that Hans Christian Oersted (1777-1851) managed to demonstrate the effect of an electric current on the behavior of a compass, thus giving rise to the study of electromagnetism.

Basic concepts of electromagnetism

Magnets and electricity have always been an object of fascination for humanity. Their initial approach took different courses that reached a meeting point at the end of the 19th century. In order to understand what electromagnetism is about, let’s review some basic concepts.

electric charge

Electric charge is a fundamental property of the particles that make up matter. The basis of all electrical charges lies in the atomic structure. The atom concentrates positive protons in the nucleus, and negative electrons move around the nucleus. When the number of electrons and protons is equal, we have a neutrally charged atom. When the atom gains an electron it remains with a negative charge (anion), and when it loses an electron it remains with a positive charge (cation).

Then it is considered the charge of the electron as the basic unit or quanta of charge electric. This is equivalent to 1.60 x 10 -19 coulomb (C), which is the unit of measurement of charges, in honor of the French physicist Charles Augustin de Coulomb.

electric field and magnetic field

A electric field It is a force field that surrounds a charge or charged particle. That is, a charged particle affects or exerts a force on another charged particle that is in the vicinity. The electric field is a vector quantity represented by the letter AND whose units are volt per meter (V/m) or newton per coulomb (N/C).

On the other hand, the magnetic field It occurs when there is a flow or movement of charges (an electric current). We can say then that it is the region where the magnetic forces act. Thus, an electric field surrounds any charged particle, and the motion of the charged particle creates a magnetic field.

Each moving electron produces a tiny magnetic field in the atom. For most materials, electrons move in different directions so the magnetic fields cancel out. In some elements, such as iron, nickel, and cobalt, electrons move in a preferential direction, producing a net magnetic field. Materials of this type are called ferromagnetic.

Magnets and electromagnets

A magnet It is the result of the permanent alignment of the magnetic fields of the atoms in a piece of iron. In an ordinary piece of iron (or other ferromagnetic material) the magnetic fields are oriented randomly, so it does not act like a magnet. The key characteristic of magnets is that they have two poles: north and south.

A electromagnet It consists of a piece of iron inside a coil of wire through which a current can be passed. When the current is turned on, the magnetic fields of each atom that make up the piece of iron align with the magnetic field produced by the current in the coil of wire, increasing the magnetic force.

electromagnetic induction

Electromagnetic induction, discovered by Joseph Henry (1797-1878) and Michael Faraday (1791-1867), is the production of electricity by means of a moving magnetic field. Passing a magnetic field through a coil of wire or other conductive material causes a flow of charge or current when the circuit is closed.

Electromagnetic induction is the basis of generators and practically all the electrical power produced in the world.

Applications of electromagnetism

Electromagnetism is the basis of the operation of the electrical and electronic devices that we use daily.


Microphones have a thin membrane that vibrates in response to sound. Attached to the membrane is a coil of wire that is part of a magnet and moves with the membrane. The movement of the coil through the magnetic field converts sound waves into electrical current which is transferred to a speaker and amplified.


Generators use mechanical energy to produce electrical energy. Mechanical energy can come from water vapor, created by the combustion of fossil fuels, or from falling water in hydroelectric plants.

Electric motor

A motor uses electrical energy to produce mechanical energy. Induction motors use alternating current to convert electrical energy into mechanical energy. These are the motors typically used in household appliances, such as fans, dryers, washing machines, and blenders.

An induction motor consists of a rotating part (rotor) and a stationary part (stator). He rotor It is an iron cylinder with grooves along which copper fins or bars are attached. The rotor is enclosed in a container of coils or turns of conducting wire through which alternating current is passed, becoming electromagnets.

The passage of alternating current through the coils produces a magnetic field which in turn induces a current and a magnetic field in the rotor. The interaction of the magnetic fields in the stator and rotor causes a twist in the rotor allowing work to be done.

Maglev: levitating trains

Magnetically levitated trains use electromagnetism to lift, guide and propel themselves along a special track. Japan and Germany are pioneers in the use of these trains as a means of transportation. There are two technologies: electromagnetic suspension and electrodynamic suspension.

The electromagnetic suspension It is based on the attractive forces between powerful electromagnets at the base of the train and the railway track. The magnetic force is adjusted so that the train remains suspended above the track, while it is propelled by a magnetic field that travels forward by interaction of side magnets in the train.

The electrodynamic suspension It is based on the repulsive force between magnets in the train and a magnetic field induced in the railway track. This type of train needs wheels to be able to reach a critical speed, similar to airplanes when they are about to take off.

Medical diagnoses

Magnetic resonance imaging is one of the most impactful technologies in modern medicine. It is based on the effect of strong magnetic fields on the hydrogen nuclei of the body’s water.

Electromagnetic phenomena

Many of the electromagnetic phenomena that we know are a consequence of the Earth’s magnetic field. This field is generated by electrical currents inside the planet. The Earth then resembles a large magnetic bar within it, where the magnetic north pole is located at the geographic south pole and the magnetic south pole corresponds to the geographic north pole.

Spatial Orientation

The compass is an instrument that dates back to approximately 200 years BC. It is based on the orientation of a magnetic metal needle towards geographic north.

Some animals and other living beings can detect the Earth’s magnetic field and thus orient themselves in space. One of the orientation strategies is through specialized cells or organs that contain magnetite crystalsan iron oxide mineral that maintains a permanent magnetic field.

The northern and southern lights

He Earth’s magnetic field It functions as a protective barrier against the bombardment of high-energy ionized particles emanating from the Sun (better known as the solar wind). These are deflected to the polar regions, exciting atoms and molecules in the atmosphere. The characteristic lights of the auroras (boreal in the northern hemisphere and southern in the southern hemisphere) are the product of the emanation of energy when excited electrons return to their basal state.

Maxwell and the theory of electromagnetism

James Clerk Maxwell deduced between 1864 and 1873 the mathematical equations that explain the nature of magnetic and electric fields. In this way, Maxwell’s equations provided an explanation of the properties of electricity and magnetism. Specifically, these equations show:

how an electric charge produces an electric field, how currents produce magnetic fields, and how changing a magnetic field produces an electric field.

Maxwell’s wave equations also served to show that changing an electric field creates a self-propagating electromagnetic wave with electric and magnetic components. Maxwell’s work unified the seemingly separate areas of physics of electricity, magnetism, and light.

See also:

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