Today, it is not surprising that, touching the switch key, we see a lighted bulb. Often we don’t even think that all such actions are based on a series of physical phenomena. One of these extremely interesting phenomena is the electrical conductivity of metals, which ensures the flow of electric current.
For starters, you should probably decide what is at stake. So, electrical conductivity is called the ability of a substance to pass an electric current. Moreover, different substances have this ability to varying degrees. According to the degree of electrical conductivity, substances are divided into conductors, semiconductors and dielectrics.
If you look at the experimental data obtained by the researchers during the study of electric current, it becomes clear that the conductivity of metals is the highest. This is confirmed by everyday practice, when metal wires are used to transmit electric current. It is metals that primarily act as conductors of electric current. And an explanation for this can be found in the electronic theory of metals.
According to the latter, the conductor is a crystal lattice, the nodes of which are occupied by atoms. They are located very densely and are connected with neighboring similar atoms, therefore they remain practically at the nodes of the crystal lattice. What can not be said about the electrons located on the outer shells of atoms. These electrons can freely move randomly, forming the so-called “electron gas”. Here is the electronic conductivity of metals and is based on such electrons.
As evidence that the nature of the electric current is due to electrons, we can recall the experience of the German physicist Rikke, set in 1901. He took two copper and one aluminum cylinders with carefully polished ends, set one on top of the other and passed an electric current through them. According to the experimenter, if the electrical conductivity of metals is due to atoms, then the transfer of matter would occur. However, after passing an electric current for a year, the mass of the cylinders did not change.
This result led to the conclusion that the electrical conductivity of metals is caused by some particles inherent in all conductors. The electron, which had already been discovered by this moment, was just suitable for this role. Subsequently, several more witty experiments were conducted, and all of them confirmed that the electric current is due to the movement of electrons.
In accordance with modern concepts of the crystal lattice of metals, ions are located in its nodes, and electrons move relatively freely between them. It is a large number of such electrons that provides high electrical conductivity of metals. In the presence of a small potential difference at the ends of the conductor, these free electrons begin to move, which causes the flow of electric current.
It should be noted here that conductivity is highly temperature dependent. So, with increasing temperature, the conductivity of metals decreases, and vice versa, increases with decreasing temperature, up to the phenomenon of superconductivity. At the same time, it should be remembered that although all metals have conductivity, its value for each of them is different. The best conductivity of the most widely used metals used in electrical engineering is copper.
So, the given material gives the concept of what constitutes the electrical conductivity of metals, explains the nature of the electric current and explains what caused it. A description is given of the crystal lattice of metals and the effect of some external factors on conductivity.