If you carefully analyze the life of modern society in technical terms, it becomes clear that the usual order of things determines the electric current. The structure of society is largely determined by it. Natural gas can be abandoned by replacing it with solid and liquid fuels; even gasoline for cars is now quite successfully replaced by analogs based on alcohol; but there’s nothing to replace the electric current: it is either there or not.
People who are only broadly familiar with electrical engineering often think that everything in this area has long been known and calculated. In fact, this is far from the case. Many of the properties that an electric current possesses are axioms (fundamental laws that do not require proof), although this does not interfere with the successful use of electrical appliances in everyday life and in production.
To the question “what is electric current”, the literature gives a definite answer - this is the directed motion of charged particles. It is known from the main course of physics that an atom consists of three components: a neutron, a proton, and a negatively charged electron (their number varies). Some electrons located in remote orbits from the nucleus that attracts them can leave the structure of the atom and remain in a “conditionally free” state. When they pass through special media formed by circuit elements, the electrons do the work that a person needs. This can be an increase in the temperature of the spiral of a heating device, the generation of a magnetic field in transformers and inductors, vibrational disturbances of magnetic fields, etc.
To create such free particles are sources of electric current. The word “creation” is only partially true, since not all sources directly generate current. Therefore, there is a division into primary and secondary. The former create a current, and the latter accumulate it and, if necessary, give it back. Current generation is performed at power plants (hydro, heat, nuclear, etc.). The windings of generating machines rotate in a magnetic field, which "knocks out" the electrons from their orbits. Then, the flow of these released particles along the power lines is directed to the transforming transformer devices, in accordance with the law of electromagnetic induction, reducing or increasing the effective voltage value. Further, the current goes to consumers, where it performs the required work. Electrons do not move “nowhere”: they are sent back to the generator, connected to the vast mass of the Earth, which can accumulate them (almost like people - tend to rest). In light of the above, it is necessary to indicate the conditions for the existence of an electric current:
- the presence of a closed loop of conductive material, which serves as a kind of bridge for electrons between the source of their occurrence (knocking out of atoms) and the earth (mass). That is why, before connecting a consumer device, there is no electric current in a normal household power outlet, but only voltage;
- the current source constantly creates their flow in the conductor. Otherwise, there will be no movement (current). If the source power is not enough to overcome the resistance of the material, then such a conductor is equated to a dielectric.
For a better understanding of the nature of the electric current, it is often compared with hydraulic systems. The current is the movement of fluid through pipes, the voltage is the difference in heights, etc. Although such a comparison cannot explain the magnetic properties, it is quite suitable for a general idea.
An interesting point: it is believed that the direct current is directed from the positive pole (plus) to the negative (minus), although in fact the electrons move in the opposite direction.