If we carefully analyze the life of modern society in technical terms, it becomes clear that the usual order of things determines the electric current.The unit of society is largely determined by him.You can refuse to natural gas, replacing it with solid and liquid fuels;even gasoline for cars are now quite successfully replaced alcohol-based counterparts;but there is nothing to replace the electric current: it is either there or it is not.
People only loosely familiar with electrical engineering, often think that in this area had long been known and calculated.In fact, far from it.Many of the properties held by the electric current, are axioms (fundamental laws that do not require evidence), although this does not prevent quite successfully use electrical appliances in the home and at work.
the question "what is the electric current" literature provides an unequivocal answer - is directed movement of charged particles.From basic physics course known that the atom consists of three components: the neutron, proton and a negatively charged electron (the number varies).Some of the electrons that are on remote orbits of attracting their kernel may leave the structure of the atom and to be in "relatively free" state.When they pass on a special medium formed by circuit elements, the electrons make a person needs a job.This can be a temperature rise of the heating coil unit, the generation of magnetic fields in transformers and inductors, vibrational perturbation magnetic fields, and so forth.
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.First create the current, and the second it accumulate and, if necessary, give.Current generation is performed at power plants (hydro, heat, nuclear and others.).Windings generating machines rotate in a magnetic field, which "knocks out" electrons from their orbits.Then, the flow of the released particles of power lines routed to the conversion device, transformers, according to the law of electromagnetic induction to reduce or increase the current value of the voltage.Further, current flows to the consumers and where does the work required.Electrons do not move into "nowhere": they are sent back to the generator coupled to the huge mass of the Earth, which can accumulate them (almost like people - tend to rest).In light of the above, you must specify the conditions for the existence of an electric current:
- presence of a closed loop of a conductive material that serves as a bridge for electrons between the source of their origin (knocking out of atoms) and the ground (earth).That is why to connect consumer appliances to ordinary household outlet of an electric current, but there is only voltage;
- current source constantly creating their flow in the conductor.Otherwise, no movement (current) will not.If the power source is not enough to overcome the resistance of the material, such a conductor is equal to the dielectric.
To better understand the nature of the electrical current it is often compared with the hydraulic system.The current - the movement of fluid through the pipes, the voltage - vertical drop and so on. While such comparisons can not explain the magnetic properties, but the overall presentation is quite suitable.
interesting point: it is believed that the constant current is directed from the positive pole (plus) to the negative (minus), although in fact the electrons move in the opposite direction.