Electric current, sources of electric current: definition and essence

From the course of physics, everyone knows that an electric current means a directed ordered motion of particles carrying a charge. To produce it, an electric field forms in the conductor. The same is necessary for the electric current to continue to exist for a long time.

Sources of electric current can be:

• Static;
• Chemical;
• Mechanical;
• Semiconductor.

In each of them, work is carried out, where the differently charged particles are separated, that is, the electric field of the current source is created. Separating, they accumulate at the poles, in the places where the conductors are connected. When the poles are connected by a conductor, particles with a charge begin to move and an electric current is formed.

Sources of electric current: invention of electric machine

Until the middle of the seventeenth century, it took a lot of effort to obtain an electric current. At the same time, a growing number of scientists dealing with this issue. And Otto von Guericke invented the world's first electric car. In one experiment with sulfur, it, melted inside a hollow glass ball, solidified and smashed the glass. Gerike strengthened the ball so that it could be twisted. Rotating it and pressing a piece of leather, he received a spark. This friction markedly eased the short-term receipt of electricity. But more difficult problems were solved only with the further development of science.

The problem was that Gerica's charges quickly disappeared. To increase the duration of the charge, the bodies were placed in closed vessels (glass bottles), and the electrified material was water with a nail. The experiment was optimized when the bottle on both sides was covered with conductive material (foil sheets, for example). As a result, we realized that we could do without water.

Frog legs as a source of current

Another way to get electricity was first discovered by Luigi Galvani. As a biologist, he worked in a laboratory where he experimented with electricity. He saw a dead frog cut its foot when it was excited with a spark from the car. But one day the same effect was achieved accidentally, when the scientist touched it with a steel scalpel.

He began to look for the reasons for the appearance of an electric current. Sources of electric current, according to his final conclusion, were in the tissues of a frog.

Another Italian, Alessandro Volta, proved the inconsistency of the "frog" nature of the current. It was observed that the greatest current appeared when copper and zinc were added to a solution of sulfuric acid. This combination is called a galvanic or chemical element.

But the use of such a tool to generate EMF would be too costly. Therefore, scientists worked on another, mechanical, way of extracting electrical energy.

How is a conventional generator arranged?

At the beginning of the nineteenth century G.H. Oersted discovered that as the current passed through the conductor, a field of magnetic origin appeared. A little later, Faraday discovered that when the field lines cross this field, an EMF is induced into the conductor, which causes a current. EMF varies depending on the speed of movement and the conductors themselves, as well as on the field strength. At the crossing of one hundred million lines of force per second, the induced EMF became equal to one Volt. It is clear that manual conducting in a magnetic field is not capable of producing a large electric current. Sources of electric current of this kind showed themselves much more efficiently with the winding of the wire on a large coil or producing it in the form of a drum. The coil was placed on the shaft between the magnet and the rotating water or steam. Such a mechanical current source is inherent in conventional generators.

Great Tesla

An ingenious scientist from Serbia Nikola Tesla, having devoted his life to electricity, has made many discoveries, which we use today. Multiphase electrical machines, asynchronous electric motors, power transmission through a multiphase AC are not all the inventions of the great scientist.

Many people are sure that the phenomenon in Siberia, called the Tunguska meteorite, actually caused Tesla. But, probably, one of the most mysterious inventions is a transformer capable of receiving a voltage of up to fifteen million volts. Unusual is both its device, and calculations that are not legally known. But in those days they began to develop vacuum technology, in which there were no ambiguities. Therefore, the invention of the scientist for the time forgotten.

But today, with the advent of theoretical physics, his work again renewed interest. The ether was recognized as a gas, to which all laws of gas mechanics apply. It was from there that the great Tesla drew energy. It is worth noting that the etheric theory was very common in the past among many scientists. Only with the emergence of STR - the special theory of relativity of Einstein, in which he denied the existence of the ether - was forgotten, although the general theory formulated later did not challenge him as such.

But for now, let us dwell in more detail on the electric current and devices that are ubiquitous today.

Development of technical devices - current sources

Such devices serve to convert different energy into electrical energy. Despite the fact that physical and chemical methods of obtaining electric energy were discovered long ago, they were widely spread only in the second half of the twentieth century, when radio electronics began to develop rapidly. The initial five galvanic pairs were replenished with 25 more types. Theoretically, the galvanic pairs can number several thousand, since free energy can be realized on any oxidizer and reducing agent.

Physical sources of current

Physical sources of current began to develop a little later. Modern technology made increasingly stringent demands, and industrial thermo- and thermionic generators successfully coped with growing tasks. Physical sources of current are devices where the thermal, electromagnetic, mechanical and energy of radiation radiation and nuclear decay is converted into electrical. In addition to the above, they also include electric, MHD generators, as well as employees for the conversion of solar radiation and atomic decay.

In order that the electric current in the conductor does not disappear, an external source is needed to maintain the potential difference at the ends of the conductor. To do this, there are sources of energy that have some electromotive force to create and maintain a potential difference. The EMF of the source of electric current is measured by the work performed when carrying the plus charge through the entire closed circuit.

The resistance inside the current source quantitatively characterizes it, determining the amount of energy loss as it passes through the source.

The power and efficiency are equal to the ratio of the voltage in the external electrical circuit to the EMF.

Chemical sources of current

The chemical source of current in the electric circuit of the EMF is a device where the energy of chemical reactions is converted into electrical reactions.

It is based on two electrodes: a negatively charged reductant and a positively charged oxidizer that contact the electrolyte. Between the electrodes there is a potential difference, EMF.

In modern devices often used:

• As a reducing agent - lead, cadmium, zinc and others;
• Oxidizer - nickel hydroxide, lead oxide, manganese and others;
• Electrolyte - solutions of acids, alkalis or salts.

Widely used dry elements from zinc and manganese. Take a vessel of zinc (with a negative electrode). Inside, put a positive electrode with a mixture of manganese dioxide with coal or graphite powder, which reduce the resistance. The electrolyte is a paste of ammonia, starch and other constituents.

An acid lead accumulator is most often a secondary chemical current source in an electrical circuit that has high power, stably operates and has a low cost. Batteries of this kind are used in a variety of areas. They are often preferred for starter batteries, which are especially valuable for cars, where they are generally monopolists.

Another common battery consists of iron (anode), nickel oxide (cathode) hydrate and electrolyte - an aqueous solution of potassium or sodium. The active material is disposed in steel nickel-plated tubes.

The use of this species declined after a fire at the Edison plant in 1914. However, if you compare the characteristics of the first and second types of batteries, it turns out that the operation of iron-nickel can be several times longer than lead-acid.

AC and DC alternators

Generators are devices that are aimed at converting mechanical energy into electrical energy.

The simplest direct current generator can be represented as a frame made of a conductor, which was placed between the magnetic poles, and the ends were connected to isolated semirings (collector). In order for the device to work, it is necessary to ensure rotation of the frame with the collector. Then it will induce an electric current, changing its direction under the influence of magnetic lines of force. In the external chain, he will go in a single direction. It turns out that the collector will straighten the alternating current, which is produced by the frame. To achieve a constant current, the collector is made of thirty-six or more plates, and the conductor consists of a plurality of frames in the form of an armature winding.

Consider the purpose of the current source in the electrical circuit. We will find out what other sources of current exist.

Electrical circuit: current, current, current source

The electrical circuit consists of a current source that, together with other objects, creates a path for the current. And the concepts of EMF, current and voltage reveal the electromagnetic processes that take place at the same time.

The simplest electrical circuit consists of a current source (battery, galvanic cell, generator, etc.), power consumers (electric heaters, electric motors, etc.), as well as wires connecting the terminals of the voltage source and the consumer.

The electrical circuit has an internal (power source) and external (wires, switches and knife switches, measuring instruments) parts.

It will work and have a positive value only if a closed circuit is provided. Any breakage causes the current to stop flowing.

The electrical circuit consists of a current source in the form of galvanic cells, electroaccumulators, electromechanical and thermoelectric generators, photocells and so on.

Electric receivers are electric motors that convert energy into mechanical, lighting and heating devices, electrolysis plants and so on.

The auxiliary equipment is the apparatuses for switching on and off, measuring devices and protective mechanisms.

All components are divided into:

• Active (where the electric circuit consists of a source of electric current, electric motors, batteries, etc.);
• Passive (which include electrical receivers and connecting wiring).

The chain can also be:

• Linear, where the resistance of the element is always characterized by a straight line;
• Nonlinear, where the resistance depends on the voltage or current.

Here is the simplest scheme, where a source of current, a key, an electric lamp, a rheostat are included in the circuit.

Despite the widespread widespread use of such technical devices, especially in recent years, people are increasingly asking themselves about the installation of alternative energy sources.

Diversity of electric power sources

What sources of electric current still exist? This is not only the sun, wind, earth and tides. They have already become so-called official alternative sources of electricity.

I must say that there are a lot of alternative sources. They are not common, because they are not yet practical and convenient. But, who knows, maybe the future will be just behind them.

So, electrical energy can be obtained from salt water. In Norway, a power plant has already been established that uses this technology.

Electric stations can also operate on fuel cells with solid oxide electrolyte.

Piezoelectric generators known to receive energy due to kinetic energy are known (pedestrian paths, recumbent policemen, turnstiles and even dance floors already exist with this technology).

There are also nano-generators, which are aimed at converting energy in the human body into an electrical one.

And what about algae that houses are heated, football swords that generate electricity, bicycles that can charge gadgets, and even finely chopped paper used as a source of current?

Of course, huge prospects belong to the development of volcanic energy.

All this is the reality of today, on which scientists work. It is possible that some of them will very soon become a completely familiar phenomenon, like electricity in homes today.

Maybe someone will disclose the secrets of the scientist Nikola Tesla, and mankind will be able to easily receive electricity from the air?