From the course of physics, everyone knows that electric current means the directed ordered movement of particles that carry a charge. To obtain it, an electric field is formed in the conductor. The same is necessary in order 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 performed, where differently charged particles are separated, that is, an electric field of a current source is created. Separated, they accumulate at the poles, at the points of connection of the conductors. 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: the invention of the electric machine
Until the middle of the seventeenth century, it took a lot ofefforts. At the same time, the number of scientists dealing with this issue has been growing. And so Otto von Guericke invented the world's first electric car. In one of the experiments with sulfur, it, molten inside a hollow glass ball, hardened and broke the glass. Guericke strengthened the ball so that it could be twisted. Rotating it and pressing a piece of skin, he got a spark. This friction greatly facilitated the short-term generation of electricity. But more difficult problems were solved only with the further development of science.
The problem was that Guerike'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 was covered on both sides with a conductive material (sheets of foil, for example). As a result, they realized that it was possible to do without water.
Frog legs as a power source
Another way to generate electricity was first discovered by Luigi Galvani. As a biologist, he worked in a laboratory where they experimented with electricity. He saw how a dead frog's leg contracted when it was excited by a spark from a machine. But one day, the same effect was achieved by accident when a scientist touched her with a steel scalpel.
He began to look for the reasons why the electric current came from. The sources of electric current, according to his final conclusion, were in the tissues of the frog.
Another Italian, Alessandro Volto, proved the failure of the "frog" nature of the current. It has been observed that the largest currentarose when copper and zinc were added to a solution of sulfuric acid. This combination is called a galvanic or chemical cell.
But using such a tool to obtain an EMF would be too costly. Therefore, scientists have been working on a different, mechanical, way to produce electrical energy.
How does a regular generator work?
In the early nineteenth century, G. H. Oersted discovered that when a current passed through a conductor, a field of magnetic origin arose. A little later, Faraday discovered that when the lines of force of this field cross, an EMF is induced in 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. When crossing one hundred million lines of force per second, the induced EMF became equal to one Volt. It is clear that manual conduction in a magnetic field is not capable of producing a large electric current. Sources of electric current of this kind have shown themselves much more effectively by winding the wire on a large coil or producing it in the form of a drum. The coil was mounted on a shaft between a magnet and rotating water or steam. Such a mechanical current source is inherent in conventional generators.
Great Tesla
The brilliant scientist from Serbia Nikola Tesla, having devoted his life to electricity, made many discoveries that we still use today. Polyphase electrical machines, asynchronous electrical motors, power transmission through multiphase alternating current - this is not the whole list.inventions of the great scientist.
Many believe that the phenomenon in Siberia, called the Tunguska meteorite, was actually caused by Tesla. But, perhaps, one of the most mysterious inventions is a transformer capable of receiving voltage up to fifteen million volts. Unusual is both its device and calculations that do not yield to known laws. But in those days they began to develop vacuum technology, in which there were no ambiguities. Therefore, the invention of the scientist was forgotten for a while.
But today, with the advent of theoretical physics, there is renewed interest in his work. The ether was recognized as a gas, to which all the laws of gas mechanics apply. It was from there that the great Tesla drew energy. It is worth noting that the ether theory was very common in the past among many scientists. Only with the advent of SRT - Einstein's special theory of relativity, in which he refuted the existence of the ether - was it forgotten, although the general theory formulated later did not dispute it as such.
But for now, let's dwell on the electric current and devices that are ubiquitous today.
Development of technical devices - current sources
Such devices are used to convert different energy into electrical energy. Despite the fact that physical and chemical methods for generating electrical energy were discovered a long time ago, they became widespread only from the second half of the twentieth century, when it began to develop rapidly.radio electronics. The original five galvanic pairs were replenished with 25 more types. And theoretically, there can be several thousand galvanic pairs, since free energy can be realized on any oxidizer and reductant.
Physical current sources
Physical current sources began to develop a little later. Modern technology made more and more stringent requirements, and industrial thermal and thermionic generators successfully coped with the increasing tasks. Physical current sources are devices where thermal, electromagnetic, mechanical and radiation and nuclear decay energy is converted into electrical energy. In addition to the above, they also include electric, MHD generators, as well as those used to convert solar radiation and atomic decay.
In order for the electric current in the conductor not to disappear, an external source is needed to maintain the potential difference at the ends of the conductor. For this, energy sources are used that have some electromotive force to create and maintain a potential difference. The EMF of an electric current source is measured by the work done by transferring a positive charge throughout a closed circuit.
Resistance inside a current source quantitatively characterizes it, determining the amount of energy loss when passing through the source.
Power and efficiency are equal to the ratio of the voltage in the external electrical circuit to the EMF.
Chemical sourcescurrent
A chemical current source in an electric circuit EMF is a device where the energy of chemical reactions is converted into electrical energy.
It is based on two electrodes: a negatively charged reducing agent and a positively charged oxidizing agent, which are in contact with the electrolyte. A potential difference arises between the electrodes, EMF.
Modern devices often use:
- as a reducing agent - lead, cadmium, zinc and others;
- oxidant - nickel hydroxide, lead oxide, manganese and others;
- electrolyte - solutions of acids, alkalis or s alts.
Zinc and manganese dry cells are widely used. A vessel made of zinc (having a negative electrode) is taken. A positive electrode is placed inside with a mixture of manganese dioxide with carbon or graphite powder, which reduces the resistance. The electrolyte is a paste of ammonia, starch and other components.
A lead acid battery is most often a secondary chemical current source in an electric circuit, with high power, stable operation and low cost. Batteries of this type are used in a variety of areas. They are often preferred for starter batteries, which are especially valuable in cars where they generally have a monopoly.
Another common battery consists of iron (anode), nickel oxide hydrate (cathode) and an electrolyte - an aqueous solution of potassium or sodium. The active material is placed in nickel-plated steel tubes.
Use of this species declined after the Edison factory fire in 1914. However, if we compare the characteristics of the first and second types of batteries, it turns out that the operation of iron-nickel can be many times longer than lead-acid.
DC and AC generators
Generators are devices that are aimed at converting mechanical energy into electrical energy.
The simplest DC generator can be represented as a frame of conductor, which was placed between the magnetic poles, and the ends connected to insulated half rings (collector). For the device to work, it is necessary to ensure the rotation of the frame with the collector. Then an electric current will be induced in it, changing its direction under the influence of magnetic field lines. In the outer chain, it will go in a single direction. It turns out that the collector will rectify the alternating current that is generated by the frame. To achieve constant current, the collector is made of thirty-six or more plates, and the conductor consists of many frames in the form of an armature winding.
Let's consider what is the purpose of the current source in the electric circuit. Let's find out what other current sources exist.
Electric circuit: electric current, current strength, current source
Electrical circuit consists of a current source, which, together with other objects, creates a path for current. And the concepts of EMF, current and voltage reveal the electromagnetic processes occurring in this case.
The simplest electrical circuit consists of a current source (battery, galvanic cell, generator, and so on), energy consumers (electric heaters, electric motors, etc.), as well as wires connecting the terminals of the voltage source and the consumer.
Electrical circuit has internal (source of electricity) and external (wires, switches and switches, instruments for measuring) parts.
It will only work and have a positive value if a closed circuit is provided. Any break causes the flow of current to stop.
The electrical circuit consists of a current source in the form of galvanic cells, electric accumulators, electromechanical and thermoelectric generators, photocells, and so on.
Electric motors act as electrical receivers, which convert energy into mechanical, lighting and heating devices, electrolysis plants, and so on.
Auxiliary equipment are devices used to turn on and off, measuring instruments and protective mechanisms.
All components are divided into:
- active (where the electrical circuit consists of an EMF current source, electric motors, batteries, and so on);
- passive (which includes electrical receivers and connecting wiring).
Chain can also be:
- linear, where the resistance of the element is always characterized by a straight line;
- nonlinear, where the resistance depends onvoltage or current.
Here is the simplest circuit, where a current source, a key, an electric lamp, a rheostat are included in the circuit.
Despite the ubiquity of such technical devices, especially in recent times, people are increasingly asking questions about installing alternative energy sources.
Variety of sources of electrical energy
What sources of electric current still exist? It is not only the sun, wind, earth and tides. They have already become the 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 s alt water. Norway has already built a power plant using this technology.
Power plants can also operate on fuel cells with solid oxide electrolyte.
Piezoelectric generators are known to be powered by kinetic energy (footpaths, speed bumps, turnstiles and even dance floors already exist with this technology).
There are also nanogenerators that are aimed at converting energy in the human body into electrical energy.
And what about algae used to heat houses, football swords that generateelectrical energy, bicycles that can charge gadgets, and even finely cut paper used as a power source?
Huge prospects, of course, belong to the development of volcanic energy.
All this is the reality of today, which scientists are working on. It is possible that some of them will soon become completely commonplace, like electricity in homes today.
Maybe someone will reveal the secrets of the scientist Nikola Tesla, and humanity will be able to easily receive electricity from the ether?
