Electromagnetic energy


The electromagnetic energy a is the amount of energy stored in a region of space that we can assign to the presence of an electromagnetic field, and that will be expressed as a function of the forces of the magnetic field and the electric field. At a point in space, the density of electromagnetic energy depends on a sum of two terms proportional to the square of the field forces.

Advantages of electromagnetic energy

An advantage of using an electromagnetic power source is that, depending on the electromechanical device used, an external electrical source is not required to generate electrical power. An example of this is an alternating current (AC) generator. When the mechanical energy of rotation turns a coil inside the generator, it exposes that coil to changes in the magnetic field. These changes induce the production of alternating current voltage, a voltage in which the current changes direction at a certain frequency, between the two output ends of the coil. Since no more energy is required than the mechanical movement of the rotating coil, this type of device can be advantageous in situations where a mechanical power source is available, such as a steam or gas turbine,

Another advantage of using an electromagnetic power source is that it can generate AC or DC power. As mentioned earlier, an AC generator uses varying magnetic fields to create AC electrical power. A DC generator works in a similar way; however, some additional parts are required to convert the power supply from AC to DC. Many direct current motors and generators use a device called a switch to convert the alternating current leaving the power generator into current that flows in only one direction, or direct current. As with an AC generator, many types of DC generators only require a reliable source of mechanical power to generate electricity.

Disadvantages of electromagnetic energy

Electromagnetic energy sources may not be as useful, or may be dangerous to use, under certain circumstances. For example, if you need to have a power supply that must have a regulated current output, the AC and DC generators must run at variable speed. Also, while a DC generator produces an electrical current that flows in one direction, the electrical current is irregular. To regulate the current produced by a DC generator, additional electrical equipment such as a battery, capacitor, and inductor and electronic components called diodes are needed to ensure that the current is kept within a controlled range.

Because generators use electromagnetic fields to produce electricity, these fields can be dangerous for some people who use sensitive medical equipment, such as pacemakers. These same electromagnetic fields can also interfere with other electrical and electronic devices, such as mobile phones and computers. The process of generating electrical energy also produces heat, so it would be better not to use a generator around elements or in environments where there is flammable or combustible material.

Study of electromagnetism

There is a lot of confusion as to who exactly discovered electromagnetic waves, electromagnetic radiation, or electromagnetic energy. However, the first records found regarding electromagnetic energy describe that electromagnetism was first discovered in 1820 by Hans Christian Orsted, a Danish physicist and chemist. When he set up the apparatus to prepare for an evening lecture, he noticed that fluctuating electrical current diverted the compass needle from its magnetic north when he turned the battery on and off; the battery is the source of the electric current. Orsted was convinced that electric current is capable of creating a magnetic field, which showed that there was a logical relationship between electric current and magnetism;

In summary, the definition of electromagnetic energy can be given as the source of energy necessary to transmit information (in the form of waves) from one place (material) to another. This information can be in the form of light, heat, or any other form. Let’s understand step by step what electromagnetic energy is.

Basic concepts

Electric charge:

It is an attribute of subatomic particles, which determines their interactions when placed in the electric and magnetic fields. Electrically charged matter is affected by the electromagnetic field and vice versa.

Electric current:

It is the movement or flow of electrically charged particles. There are two types of charged particles, that is, positively charged particles, that is, protons, and negatively charged particles, that is, electrons.


Magnetism is a force that affects the interaction of charged materials or particles in motion, developing attractive or repulsive forces between them.

Electromagnetic wave:

It is a wave created by the acceleration of charged particles that are placed in the magnetic and electric field; both fields act at right angles to each other. The oscillation of the particles in the wave emits an energy called electromagnetic wave energy.

Electromagnetic spectrum energy:

A spectrum of electromagnetic waves of all possible frequencies and wavelengths forms an electromagnetic spectrum. The total energy of the spectrum is called the energy of the electromagnetic spectrum.

Electromagnetic radiation:

Electromagnetic radiation is a set of electromagnetic waves that travel in a vacuum or in matter. The energy radiated by electromagnetic waves is called electromagnetic radiation energy.

Electromagnetic field:

The electromagnetic field is caused by electrically charged objects, which influence the behavior of charged materials or particles throughout the field. The total amount of energy in the field and in the affected materials is called the electromagnetic field energy.

Examples of electromagnetic energy


The mechanism of these devices, every day, consists of the circulation of an electric charge by means of an electromagnet, whose magnetic field attracts a small metal hammer to a bell, interrupting the circuit and allowing it to restart, so that the hammer it hits it repeatedly and produces the sound that attracts attention.

Magnetic suspension trains:

Instead of rolling on the tracks like conventional trains, this ultra-technological train model is made of magnetic levitation thanks to the powerful electromagnets installed in its lower part. The electrical repulsion between the magnets and the metal of the platform on which the train runs keeps the weight of the vehicle in the air.

Electric transformers:

A transformer, these cylindrical devices that in some countries we see on power lines, serve to control (increase or decrease) the voltage of an alternating current. This is achieved by means of coils arranged around an iron core, whose electromagnetic fields allow the intensity of the output current to be modulated.

Electric motors:

Motors, as we all know, transform energy into movement, through a combination of rotor and extractor. The first is mobile and contains a series of coils, which are located between the fixed poles of the magnet that is the extractor. This movement is kept constant thanks to the electromagnetic field and allows, through a switch, to produce a curve that moves the vehicle forward.

We dynasty them:

These devices are used to take advantage of the rotation of the wheels of a vehicle, such as a car, to turn a magnet and produce a magnetic field that supplies alternating current to the coils.

The phone:

The magic of this everyday device is none other than the ability to convert sound waves (such as voice) into modulations of an electromagnetic field that can be transmitted, initially by a cable, to a receiver at the other end that is capable of spilling the process and recover the electromagnetically contained sound waves.


These devices work from the generation and concentration of electromagnetic waves in food. These waves are similar to those used for radiocommunication, but of high frequency that transform the diplodes (magnetic particles) of food at very high speeds, as they try to align themselves with the resulting magnetic field. This movement is what generates the heat.

Magnetic resonance imaging (MRI):

This medical application of electromagnetism has been an unprecedented breakthrough in health since it allows us to examine in a non-invasive way within the body of living beings the electromagnetic manipulation of the hydrogen atoms contained in it, to generate a field interpretable by specialized computers. .


These devices, so common today, work thanks to a diaphragm attracted by an electromagnet, whose sensitivity to sound waves allows them to be translated into an electrical signal. This can be remotely streamed and decoded, or even stored and played back later.

Mass spectrometers:

It is a device that allows the composition of certain chemical compounds to be analyzed with great precision by means of the magnetic separation of the atoms that compose them, by means of their ionization and reading by a specialized computer.


Electronic instruments whose purpose is to graphically represent electrical signals that vary over time from a specific source. To do this, they use a coordinate axis on the screen whose lines are the result of measuring the voltages from the determined electrical signal. They are used in medicine to measure the functions of the heart, brain, or other organs.

On the contrary, an analysis of the mean amplitudes shows that, for the practical purposes pursued, it can be considered constant throughout the year and even with its course (French and Russian researchers indicate differences of 4 to 5% in 18 years) ; disappearing the risk of periods of drought, characteristic of hydroelectric plants.

Magnetic cards:

This technology allows the existence of credit or debit cards, which have a somewhat polarized magnetic strip, to encrypt the information on the orientation of their ferromagnetic particles. By entering information into them, designated devices polarize these particles in a specific way so that the order can be “read” to retrieve the information.

Digital storage on magnetic tapes:

Key in the world of computers and computers, it stores large amounts of information on magnetic disks whose particles are polarized in a specific way and are decipherable by a computerized system. These disks can be removable, like existing floppy disks or pendrives, or they can be permanent and more complex, like hard disks.

Magnetic drums:

This data storage model, popular in the 1950s and 1960s, was one of the earliest forms of magnetic data storage. It is a hollow metal cylinder that rotates at high speeds, surrounded by a magnetic material (iron oxide) on which the information is printed by means of a coded polarization system. Unlike the discs, it did not have a read head and this allowed a certain agility in the retrieval of information.

Bike lights:

The lights built into the front of the bicycles, which turn on when they move, work thanks to the rotation of the wheel to which a magnet is attached, whose rotation produces a magnetic field and, therefore, a modest source of electricity alternates. This electrical charge is conducted to the bulb and is translated into light.

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