What is electromagnetism ? In general terms, this name identifies that branch of physics that focuses on electrical and magnetic phenomena and their correlations. In practice, electromagnetism studies the interactions between electric and magnetic fields through the famous Maxwell equations .
The latter are the starting point for any study in electrology , because they explain and provide an adequate explanation for any type of electrical, electromagnetic or magnetic phenomenon.
In more practical terms, electromagnetism is the current which, by passing through an iron element, makes it magnetic because it produces a polarity. When the current is suspended and, therefore, its passage through the iron element is interrupted, the latter no longer has any magnetic characteristics. This means that when current flows from the positive pole to the negative pole inside a conductor, a magnetic field is produced perpendicular to the direction of flow of the current, and whose intensity is proportional to the intensity of the current. The greater the current flowing inside the conductor, the more intense the magnetic field that will be produced.
It is therefore important to remember that the electric and magnetic fields are deeply interconnected, in the sense that no propagation of an electric field is possible if it is not accompanied by a magnetic field. In physics, electromagnetic waves are produced as a result of the acceleration of electrical charges.
Magnetism and electromagnetism: differences
If magnetism can be defined as the property of some bodies to attract ferrous objects – called natural / artificial magnets or magnets – electromagnetism was discovered in 1820 by the Danish physicist Hans Oersted, observing that a needle free to rotate was influenced by the passage of electric current.
The first experiment on electromagnetism conducted by Oersted involved the construction of a circuit consisting of a conductor wire located in a north-south direction, fixed by geographic poles. A magnetic needle was placed under the thread which spontaneously placed itself in the same direction as the thread. With the circuit closed and the passage of electric current along the conductor, the needle moved, changing direction, when the current was intense, placing itself perpendicular to that of the thread.
In conclusion, therefore, electromagnetism explains the physical process through which a conductor covered by sufficiently intense electric charges moves in space and positions itself in the direction perpendicular to that of the wire.
Electromagnetism in metalworking: the SPD electro-permanent system
On the basis of what has been illustrated so far, it is easy to understand that if electromagnetism were used to anchor metal pieces during their processing, the suspension of the current would cause release of the piece with consequent risk for the operators.
To solve this problem, SPD has developed an electro-permanent system intended for its magnetic surfaces which produces a current shock such as to magnetize the iron piece. In practice, this means that the production of direct current will no longer be necessary to operate, but on the contrary it will be possible to operate with safer and more sustainable technology .
The advantages of the SPD signed electro-permanent system are manifold:
- No fall of the piece on suspension of the electric current, because the piece is semi-permanently magnetized
- No risk for the operators involved
- No deformation of the piece, which does not need to be anchored manually
- No overheating of the piece and therefore no alteration of its physical characteristics
- Greater number of free faces to work, because the anchoring takes place on only one side of the madman
- Uniform anchoring and therefore easier processing
- Control of the piece no longer mechanical but automatic, with a consequent increase in the safety and reliability of the processes
There was only one last intuition to complete the experimental framework of electromagnetism, which then led to the second industrial revolution. It was Michael Faraday (1791-1867) who, on the basis of Oersted’s studies, concluded, verifying it experimentally, that if electricity can produce magnetism, magnetism can also produce electricity. This incredible discovery, electromagnetic induction, laid the foundations for the development of all those applications that allow to transform mechanical energy into electrical energy, as happens for example in the dynamo of a bicycle.
But how is it possible that two bodies distant from each other, like two electric charges, interact without touching each other? Today, physicists answer this question by referring to the existence of a gravitational field , an electric fieldand the mediators of the forces.
It was Faraday who first introduced the concept of field: the Sun influences the movement of the Earth producing a gravitational field in every point of space and is the field itself responsible for the movement of the Earth and not the Sun. Similarly, a charged object produces a field electric at any point in space, through particles called mediators, which by propagating the information of the electric field in space, interact with other electric charges. In the case of electromagnetism the mediators are photons. It was therefore Newton, Coulomb, Oersted, Ampère and Faraday, together with many other important physicists, who laid the foundations of the theory of electromagnetic force, but Maxwell, one of the most important scientists ever lived, was the real father. Using the powerful tool of mathematics, he put together all the experimental results obtained in the form of four differential equations, thus expressing all the empirical laws developed in the previous decades and unifying electricity and magnetism vd in a single theory.