From the course of physics it is known that one of the characteristics of any body is its ability to do work, since the latter is nothing but the conversion of one type of energy into another (for example, potential into kinetic). In this case, one should take into account the famous law of energy conservation formulated in the XVIII century M.V. Lomonosov, according to which energy never disappears anywhere, it only changes, takes a different form. All of the above applies equally not only to solids, but also to other types of matter, including electric current.
Electric current, as has long been proven, is the directional movement of charged particles. Moving along a specific section of the circuit, these particles form an electric field that does the work. The work of an electric current is the amount of energy that must be expended in order to transfer a charge along a given electrical circuit. In this case, not all current work is useful and effective. A sufficiently significant part of the energy is spent on the fact that the electric charge overcomes the resistance of elementary particles located in the conductor and in the source of the circuit.
The work of electric current, the formula of which, as follows from the above text, A = U • Q, is the most important characteristic of this special kind of matter. In this formula, U represents the potential difference (voltage) on a section of the circuit, and Q is the quantitative expression of the charge transferred over this section.
However, the work of electric current alone would not be of particular interest if it were not found for the regularity that linked this work and the amount of thermal energy released in this case . This regularity was discovered almost simultaneously by two well-known physicists - Lenz and Joed Prescott, and therefore the law in the scientific community was called the "Joule-Lenz law". According to this law, it turns out that the amount (or power) of heat that is released in a certain volume when charged particles flow through it is directly dependent on the product of the field strength and the density of the electric current flowing through this section. This law is of great importance for calculating the loss of electricity during transmission through wires over long distances.
The work of electric current is most directly connected with another most important quantity - power. Under current power in physics, we understand the quantitative characteristic of the conversion and the transmission rate of electrical energy. Power is measured in kilowatt hours, while the work of electric current is measured in joules.
To obtain maximum current power from a particular source, it is necessary to take into account the characteristics of this source, as well as the fact that the resistances of the internal and external circuits must be comparable with each other, otherwise all the work done will go to overcome the difference in the resistances.
The work of electric current is the most important physical characteristic that must be taken into account in almost all industries, as well as in the production and transmission of energy over significant distances.