Specific conductivity as the most important characteristic of conductors of electric current

Motion of electric current in conductorsinevitably accompanied by the action of certain physical forces that impede this movement. From the point of view of the atomic-molecular theory of the structure of matter, the basis of this phenomenon lies in the fact that charged electrons collide with the atoms that make up the material of the conductor during their movement.

As the results of numerousresearch, the number of such electron collisions is directly related to the ability of a material to pass an electric current through itself with minimal losses. Accordingly, the countermeasures that the conductor material exerts through the electric current passing through it, received in physics the name "electric resistance of the conductor."

The resistance is in direct dependenceof the voltage and inversely proportional to the current. In accordance with the international system of units of measurement, it is denoted by the letter R and is measured in Ohms.

At the same time, often when creating those or othermaterials, it is not the active resistance of the conductor to the passage of an electric current through him that is more important, but the fact that he is capable of carrying this current. The concept, the reverse of the electrical resistance, is the conductivity.

Specific electrical conductivity appliedin physics, characterizes the general ability of a particular body to be the conductor of an electric current. Quantitatively, the conductivity is the reciprocal of the resistivity. It is denoted by the letter γ and is measured in terms of m / ohm mm2 or in simens / meter.

In accordance with the basic law of electrical engineering- Ohm's law - the value of the conductivity shows the interdependence between the current density that arises in a particular conductor and the numerical value of the electric field that appears in one or another medium. However, this position is valid only for a homogeneous medium, in a nonuniform layer, the conductivity is just a tensor.

Of metals, the highest specific conductivityis characteristic of silver and copper. This is due primarily to the structural features of their crystal lattices, which make it possible to move relatively easily to charged particles (electrons and ions).

It is only natural that pure metals possesshigher conductivity than alloys; therefore, in industry, for electrical purposes, they try to use the highest possible pure copper with an admixture fraction of not more than 0.05%. By the way, the conductivity of copper is 58.5 mm / mm ^ 2, which is much higher than the vast majority of other metals.

In addition to metallic conductors,industry and everyday life were widely used conductors from nonmetals, the most common of which is coal. From it, in particular, special brushes are made for electric machines, electrodes used in searchlights, etc.