Which source is called a current source. Electric current, sources of electric current: definition and essence. Mechanical current sources
Current sources devices that convert different kinds energy into electrical energy. Based on the type of energy converted, energy sources can be divided into chemical and physical. Information about the first chemical batteries (galvanic cells and batteries) dates back to the 19th century. (for example, Volta battery, Leclanche cell). However, until the 40s. 20th century In the world, no more than 5 types of galvanic pairs have been developed and implemented in designs. From the mid-40s. As a result of the development of radio electronics (see Radio electronics) and the widespread use of autonomous electrical circuits, about 25 more types of galvanic pairs have been created. Theoretically, the free energy of chemical reactions of almost any oxidizing agent and reducing agent can be realized in electrical energy, and therefore, the implementation of several thousand galvanic pairs is possible. The operating principles of most physical electronic technologies were already known in the 19th century. Subsequently, due to the rapid development and improvement, Turbogenerators and Hydrogenerators became the main industrial sources of electricity. Physical technologies based on other principles received industrial development only in the 50s and 60s. 20th century, which is due to the increased and rather specific requirements of modern technology. In the 60s technically developed countries already had industrial samples of thermogenerators, thermionic generators (USSR, Germany, USA), nuclear batteries (France, USA, USSR). Technological progress, the penetration of electrical engineering and electronics into transport, everyday life, medicine, etc. stimulated the development of autonomous power sources, among which chemical ones occupied a prominent place in quantitative terms, becoming mass consumer products. Portable lighting devices, tape recorders and radios, televisions and portable medical equipment, railway equipment. transport, cars, tractors, airplanes, artificial satellites, spaceships, communications equipment, and much more are equipped with small-sized electronic devices. The theory of electric current provides for the study of all stages of the process of generating electric current on the basis of modern concepts of the physics of solids, liquids, and gases, charge transfer processes, and electrochemical reactions. The theory of information technology also studies optimization issues, including both the selection of initial parameters that provide optimal output characteristics of information technology and the development of methods for predicting the characteristics of future information technology. the most important characteristics These include: efficiency, energy intensity (or specific energy intensity), power (or specific power per unit mass, volume, etc.), service life, quality of generated electricity (frequency, voltage, overload capacity, cost , reliability). Chemical current sources It is customary to call devices that generate electric current using the energy of redox reactions of chemical reagents. In accordance with the operating scheme and the ability to supply energy to the electrical network, chemical generators are divided into primary, secondary, and backup, as well as electrochemical generators. Primary energy sources (galvanic cells and batteries) allow, as a rule, a one-time use of the energy of chemical reagents. Certain designs of voltaic cells and batteries allow short-term reuse of reactant energy after electrical recharging. The positive (cathode) and negative (anode) electrodes, separated by an electrolyte in a liquid or paste state or by a porous separator membrane with the electrolyte absorbed in it, are electrically connected (galvanic connection) during the entire service life of the electrolyte. Physical current sources are devices that convert thermal, mechanical, electromagnetic energy, as well as the energy of radiation and nuclear decay into electrical energy. In accordance with the most commonly used classification, physical generators include: electric machine generators, thermoelectric generators, thermionic converters, MHD generators, as well as generators that convert the energy of solar radiation and atomic decay. Electric machine generators, which convert mechanical energy into electrical energy, are the most common type of electrical energy sources, the basis of modern energy. They can be classified by power (from fractions Tue up to hundreds MW), by purpose and operating characteristics (stationary, transport, backup, etc.), by type of prime mover (diesel generators, turbo and hydrogen generators), by working fluid (steam, water, gas), etc. Thanks to a long period of theoretical, design, and technological improvement, the characteristics of this type of electrical generator have reached values close to the limit (see Electric machine generator). The operation of a thermoelectric generator (TEG) is based on the use of the Seebeck effect. The working material in TEGs are various semiconductor compounds of silicon, germanium, etc. (usually solid solutions). TEG efficiency is from 3 to 15% in the temperature range from 100 to 1000°C. Research on TEGs is being conducted in the USSR, USA, France, etc. Areas of possible application of TEGs: autonomous power supplies (in transport, communications technology, medicine), anti-corrosion protection (on main pipelines), etc. (see Thermoelectric generator). The operating principle of a thermionic converter (TEC) is based on the use of the thermionic effect (the emission of electrons by the surface of a heated metal). The thermionic electron flux depends mainly on the temperature and surface properties of the material. The efficiency of individual laboratory samples of TEC reaches 30%, and of existing power plants 15% (with the electrical power removed from a unit of cathode surface being 30 Tue/cm 2). The most promising application of TECs is as autonomous sources of high power electricity (up to 100 kW). Work on TEC is being carried out in the USSR, USA, Germany, France, etc. (see Thermionic energy converter). The operating principle of solar radiation transformers is based on the use of the internal photoelectric effect (see Photoelectric phenomena). A photovoltaic generator (solar battery) is a set of valve-type photocells that convert the energy of solar radiation into electrical energy. Almost direct conversion of solar radiation energy became possible only after the creation in 1953 of a highly efficient photocell made of monocrystalline silicon. The best examples of silicon solar cells have an efficiency of about 15%; their service life is practically unlimited. Solar batteries are used mainly in space technology, where they occupy a dominant position as energy sources on artificial Earth satellites, orbital stations and spacecraft, as well as for supplying electricity to areas remote from power lines with a large number of sunny days per year, for example in the Turkmen SSR, India, Pakistan (see Solar engineering). I. t., converting the energy of atomic decay (atomic batteries), use kinetic energy electrons produced during β-decay. These electronic technologies were in the development stage by 1971, and their practical use requires the solution of many design and technological problems. The efficiency of nuclear batteries is low (up to 1%), and the scope of application can only be determined after sufficient experience in their use has been accumulated. Lit. see articles describing specific types of current sources. N. S. Lidorenko.
Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .
See what “Current sources” are in other dictionaries:
Devices that convert various types of energy into electricity. Conventionally, a distinction is made between chemical current sources, in which electricity is generated as a result of a redox reaction (galvanic cells), and physical... ... encyclopedic Dictionary
See Chemical current sources, Physical current sources. Encyclopedia "Technology". M.: Rosman. 2006 ... Encyclopedia of technology
Devices that convert various types of energy into electrical energy. Based on the type of energy converted, energy sources can be divided into chemical and physical. Chemical and so-called. devices that generate electricity. energy resulting from oxidation... ... Big Encyclopedic Polytechnic Dictionary
Devices that convert various types of energy into electrical energy. Conventionally, chemicals are distinguished. Etc., in which electricity is generated as a result of oxidation. will restore. reactions, and physical I. t., converting thermal, mechanical, electrical. magnetic, as well as... ... Natural science. encyclopedic Dictionary
- (abbr. HIT) devices in which the energy of the chemical reactions occurring in them is directly converted into electrical energy. Contents 1 History of creation 2 Operating principle ... Wikipedia
Devices that generate electrical energy through the direct conversion of chemical energy through redox reactions. The first chemicals and t. created in the 19th century. (Voltaic pillar, 1800; Daniel Jacobi element, 1836; Leclanche element... Great Soviet Encyclopedia
Chemical current sources, the design of which allows long time keep them in an inactive (non-working) state and, if necessary, put them into operation, ensuring access of the electrolyte to the electrodes or transferring the electrolyte to the working state... ... encyclopedic Dictionary
When talking about the use of electrical energy in everyday life, in production or transport, then they mean the operation of electricalcurrent Electric current is supplied to the consumer from the power plantby wire. Therefore, when the houses suddenly go outelectric lamps or the movement of electric trains stops,trolleybuses, they say that the current has disappeared in the wires.
In order for an electric current to exist in conductors for a long time, it is necessary to maintain an electric field in it all this time. Electric field in conductors is created and can be maintained for a long time by sources of electric current.
A current source is a device in which some type of energy is converted into electrical energy.
In any current source, work is done to separate positively and negatively charged particles, which accumulate at the poles of the source. The separated particles accumulate at the poles of the current source. This is the name of the places to which conductors are connected using terminals or clamps. One pole of the current source is charged positively, the other - negatively. If the poles of the source are connected by a conductor, then under the influence of an electric field, free charged particles in the conductor will begin to move in a certain direction, and an electric current will arise.
There are different types of current sources:
Mechanical current source
Mechanical energy is converted into electrical energy.
These include: an electrophore machine (the disks of the machine are driven into rotation in opposite directions. As a result of the friction of the brushes on the disks, charges of the opposite sign accumulate on the conductors of the machine), a dynamo, and generators.
Thermal current source
Internal energy is converted into electrical energy.
For example, a thermoelement - two wires made of different metals it is necessary to solder from one edge, then heat the place of the solder, then tension will appear between the other ends of these wires.
Used in temperature sensors and geothermal power plants.
Light current source
Light energy is converted into electrical energy.
For example, a photocell - when certain semiconductors are illuminated, light energy is converted into electrical energy. Solar batteries are made from photocells.
They are used in solar batteries, light sensors, calculators, and video cameras.
Chemical current source
As a result of chemical reactions, internal energy is converted into electrical energy.
Galvanic cells are the most common sources of direct current in the world. Their advantage is ease and safety of use. Batteries were invented a long time ago, at the dawn of the development of electricity. Back then they didn’t know how to transmit current over long distances; they used it only within the laboratory. But to this day, various battery options have not lost their relevance. There are disposable and reusable batteries - accumulators.
Disposable batteries exhaust their full potential during use and are no longer suitable.
In everyday life, batteries are often used that can be recharged many times - accumulators (from the Latin word accumulator - to accumulate). The simplest battery consists of two lead plates (electrodes) placed in a sulfuric acid solution.
For the battery to become a source of current, it must be charged. To charge, direct current from some source is passed through the battery. During the charging process, as a result of chemical reactions, one electrode becomes positively charged and the other negatively charged. When the battery is charged, it can be used as an independent power source. The battery poles are marked with “+” and “-” signs. When charging, the positive pole of the battery is connected to the positive pole of the current source, and the negative pole is connected to the negative pole.
Sources of electric current Completed by: Anton Rubtsov, grade 8 B student of Municipal Educational Institution Secondary School No. 105 Scientific supervisor: E. A. Maslova, physics teacher
Choosing a topic I wanted to study the history of the creation of electric current sources, and also make some sources with my own hands, repeating the experiments of famous scientists. Relevance Humanity cannot exist without electrical energy, and perhaps someone will be able to discover new sources of electrical current that are more economical and less expensive. The purpose of the work is to study the main types of electric current sources, the principle of their operation and making the sources with your own hands. Objectives: 1. Consider the main types of sources of electric current. 2. Study the principle of operation of current sources. 3. Make some sources with your own hands.
Main part A current source is a device in which some type of energy is converted into electrical energy. In any current source, work is done to separate positively and negatively charged particles that accumulate at the poles of the source. Electric current is the directed (ordered) movement of charged particles (electrons, ions, etc.). The direction of movement of positively charged particles is taken as the direction of the current. If the current is created by negatively charged particles (for example, electrons), then the direction of the current is considered opposite to the direction of motion of the particles.
The history of the creation of the first current sources
Properties of amber Thales of Miletus was the first to pay attention to electric charge. He discovered that amber, rubbed with wool, acquires the properties of attracting small objects. Fossilized resin of ancient trees that grew on our planet 38-120 million years ago.
Electric machine Otto von Guericke Otto von Guericke invented the first electric machine. He poured molten sulfur inside a hollow glass ball, and then, when the sulfur hardened, he broke the glass. Guericke then strengthened the sulfur ball so that it could be rotated with a handle. To obtain a charge, it was necessary to rotate the ball with one hand, and with the other, press a piece of skin against it. The friction raised the tension of the ball to a value sufficient to produce sparks several centimeters long.
Leyden Jar A Leyden jar is a glass bottle wrapped in foil on both sides. There is a metal rod inside the jar. A jar connected by plates to an electric machine could accumulate a significant amount of electricity. If its plates were connected with a piece of thick wire, then a strong spark would jump at the point of the short circuit, and the accumulated electric charge would instantly disappear. This made it possible to obtain a short-term electric current. Then the jar had to be charged again. Now we call such devices electric capacitors.
Galvani's element Luigi Galvani (1737-1798) is one of the founders of the doctrine of electricity; his experiments with “animal” electricity laid the foundation for a new scientific direction - electrophysiology. As a result of experiments with frogs, Galvani suggested the existence of electricity within living organisms. A galvanic cell, a battery, was named after him.
Voltaic column Alesandro Volta (1745 - 1827) - Italian physicist, chemist and physiologist, inventor of a source of direct electric current. Its first source of current is a “voltaic column”. Volta alternately placed several dozen small zinc and silver circles on top of each other, placing paper moistened with salted water between them.
Main types of electric current sources Mechanical Thermal Light Chemical Thermal element Photocell Electrophore machine Galvanic cell
Animal current sources
Electricity inside living organisms Many plants experience damage currents. Sections of leaves and stems are always negatively charged relative to normal tissue.
Animals that produce electric current Electric stingray (up to 220 V) American catfish (up to 360 V) Eel (up to 1200 V)
Fruits and vegetables that produce electric current. Fruits and vegetables can be divided into those that initially contain and those that acquire intra-alkaline or acidic balance through the process of oxidation. The first include citrus fruits (lemon) and potatoes. And to the second, for example pickle and pickled tomato.
Atmospheric electricity When air moves, various air currents become electrified as a result of contact. One part of the cloud (upper) is positively electrified, and the other (lower) is negatively electrified. At the moment when the charge of the cloud becomes large, a powerful electric spark—lightning—jumps between its two electrified parts.
Practical part
Homemade batteries To make homemade batteries, we will need instruments and materials: Copper plate Zinc plate Lemon, cucumber, soda, water, coins Voltmeter Connecting wires
Galvanic cell made from lemon Produces electric current with voltage
Galvanic cell from the first pickled cucumber Produces electric current with voltage
Galvanic cell from the second and third cucumbers
A battery of two pickled cucumbers produces an electric current with voltage
A battery of three pickled cucumbers produces an electric current with voltage
A light bulb connected to a chain of three pickled cucumbers. The chain has been assembled. The light bulb lights up.
Soda battery Produces electric current with voltage
Soda battery of two and three cells
A light bulb connected to a circuit of three soda elements. The circuit has been assembled. The light bulb lights up.
Salted battery Produces electric current with voltage
Conclusion To achieve the goal of this work, I solved the following problems: Considered the main types of sources of electric current. 1. Mechanical current sources 2. Thermal current sources 3. Light current sources 4. Chemical current sources Studied the principle of operation of current sources. I made some sources with my own hands. 1. Galvanic cell made of lemon. 2. Galvanic cell made from pickled cucumber. 3. Soda battery. 4. Salted battery.
Bibliography Abramov S.S.. Great Encyclopedia of Cyril and Mythodius. 2009 Wikipedia - the free encyclopedia. www. ru. wikipedia. org. Julian Holland. Large illustrated encyclopedia of the erudite. "Swallowtail" 2001; Kartsev V.P. Adventures of the Great Equations. M.: Education, 2007
CURRENT SOURCES, devices that convert various types of energy into electrical energy. Based on the type of energy being converted, current sources are conventionally divided into chemical and physical. The first information about chemical current sources (galvanic cells and batteries) dates back to the 19th century (for example, voltaic column, 1800; Daniel-Jacobi cell, 1836; lead battery, 1859). Until the 1940s, only a few types of galvanic cells and batteries were developed and put into practice in the world; Subsequently, due to the development of radio electronics and the widespread use of autonomous power supplies, their production continuously expanded. Portable lighting devices, tape recorders and radios, televisions and portable medical equipment, vehicles, aircraft and spacecraft and much more are equipped with small-sized current sources. The first electric machine generator of direct current was created by B. S. Jacobi in 1842. Since the 1920s, turbogenerators and hydrogenerators have been used as industrial sources of electricity. Physical current sources based on other principles (thermoelectric generators, thermionic converters, solar panels, etc.) were developed and developed in the 2nd half of the 20th century, due to the increased requirements of modern technology.
The most important characteristics of current sources include: efficiency, energy intensity (or specific energy intensity), power (or specific power per unit mass, volume), service life, quality of generated electricity (frequency, voltage, ability to overload, cost, reliability).
Chemical current sources produce electric current due to the energy of redox reactions. In accordance with the operational scheme and the ability to supply energy to the electrical network, chemical current sources are divided into primary, secondary and fuel elements; A separate group consists of backup current sources. Primary current sources (galvanic cells and batteries) assume, as a rule, a one-time use of energy from chemical reagents, after which they are consumed (after discharge) and become inoperative. In such current sources, positive and negative electrodes, separated by an electrolyte, are electrically connected (galvanic connection) during the entire service life of the current source. Secondary current sources (electric batteries and rechargeable batteries) allow for repeated use of the energy of the constituent chemical reagents; after discharge, they can be recharged by creating current from an external source in the opposite direction. The electrodes and electrolyte are in electrical contact with each other throughout the battery life. To increase the service life of batteries, methods for dry-charged storage of batteries have been developed; Such batteries are first filled with electrolyte before switching on. Fuel cells (electrochemical generators) are capable of continuously generating electric current for a long time due to the constant supply of new portions of reagents from the outside to the electrodes and the removal of reaction products. The most promising generators are those that directly convert the energy of natural fuels into electricity.
Backup current sources allow only a one-time use of the energy of chemical reagents, but, unlike galvanic cells, the reagents and the electrolyte in them are brought into contact (activated) immediately before the start of the discharge. The electrolyte in such current sources is stored in a separate vessel and is poured immediately before the load is turned on or is in a solid state and melts before the load is turned on. Backup current sources are used mainly to power electrical equipment that is in a standby (non-working) state for a long time; The shelf life is up to 15 years or more. See also Chemical current sources.
Physical current sources convert thermal, mechanical, electromagnetic energy, as well as the energy of radiation and nuclear decay into electrical energy. In accordance with the most commonly used classification, physical current sources include: electric machine and thermoelectric generators, thermionic converters, magnetohydrodynamic (MHD) generators, as well as generators that convert the energy of solar radiation and atomic decay.
Electric machine generators, which convert mechanical energy into electrical energy, are the most common type of electrical energy sources, the basis of modern energy. They can be classified by power (from fractions of W to units of GW), by purpose and operating features (stationary, transport, backup, etc.), by the type of primary engine (for example, turbo and hydrogen generators), by working fluid (steam, water, gas), etc. Thanks to a long period of design and technological improvement, the characteristics of this type of current sources have reached values close to the limit.
Thermoelectric generator (TEG) is used to directly convert thermal energy into electrical energy; The action is based on the use of the Seebeck effect. The most effective TEGs are those based on PP thermoelements; their power is up to several hundred kW, efficiency is up to 20%. The main advantages of TEGs compared to electrical machine converters include the absence of moving parts, high reliability, long service life (up to 25 years), and the ability to operate in a wide temperature range; disadvantages - low efficiency and relatively high price. Areas of application of TEGs are autonomous power supplies (in transport, communications technology, space technology), anti-corrosion protection (on main pipelines), etc.
The operation of a thermionic energy converter (TEC) is based on the phenomenon of electron emission from the surface of a heated metal (see Thermionic emission). The current strength in the TEC is limited by the emission current strength of the cathode; the efficiency significantly depends on the heating temperature of the electrodes and reaches 30% (at a cathode temperature above 3000 K), the specific electrical power (per 1 cm 2 of the cathode surface) does not exceed tens of W. TECs have not received industrial application (mainly due to low economic indicators); Their most promising use is in small-sized electrical devices of low power.
Since the 1990s, photovoltaic generators have become increasingly widespread, directly converting the energy of solar radiation into electrical energy (see Solar battery); The action is based on the use of the internal photoelectric effect. The electric current in them arises as a result of processes occurring in the photocell when light radiation hits it. Silicon-based solar cells are the most efficient; their power is up to 10 kW, efficiency is 10-20%; service life is practically unlimited. Such current sources are used mainly at spacecraft, automatic weather stations, and also to supply electricity to areas remote from the power line with a large number of sunny days a year.
A magnetohydrodynamic generator converts the energy of an electrically conducting medium (for example, low-temperature plasma) moving in a magnetic field into electrical energy. The efficiency of such current sources is up to 40% with a power of about 500 MW in one unit. For industrial energy, the most promising is the creation of plasma MHD generators using natural organic fuel (gas, coal). By the beginning of the 2000s, a number of MHD installations with an electrical power of up to several tens of MW have been developed and are in pilot industrial operation in Russia, the USA, Japan and other countries.
A nuclear battery converts the energy released during the decay of radioactive element nuclei into electrical energy. The power of nuclear batteries usually does not exceed several hundred W, voltage up to 20 kV, service life up to 25 years. The area of possible application is power sources, for example, on spacecraft, in measuring instruments, in medical electronic equipment.
Lit. See articles describing specific types of current sources.
A current source is a device that converts various types of energy into electricity. Such sources can be roughly divided into physical and chemical.
Current source and its history
The first chemical galvanic cells and batteries appeared in the nineteenth century (Leclanche cells and Volta batteries). However, until approximately the forties of the twentieth century, the advantages provided by the current source were not actually used. There were only a few galvanic pairs. But literally since the mid-forties, thanks to the rapid development of radio electronics, almost three dozen new types of pairs of galvanic elements have appeared. Theoretically, a current source is the realization of the free energy of almost any chemical reaction of a reducing agent and an oxidizing agent. Therefore, it is possible to implement more than a thousand galvanic pairs. The physical current source became widespread in industry in the early sixties of the last century. This is due to the specific requirements of technology in production. By the end of the sixties, most technologically advanced countries had thermal generators, thermionic generators and nuclear batteries.
Current source and its main characteristics
Technological progress has stimulated the development of power supplies, especially autonomous ones. The current source today can be found in portable lighting devices, radios, tape recorders, televisions, medical equipment, cars, airplanes, tractors, spacecraft and many other things. The main characteristics and parameters of electricity sources can be called: energy intensity, specific energy intensity, nominal and specific power, efficiency (coefficient useful action), service life, reliability, frequency, overload capacity, voltage, rated current, cost.
Types of current sources
In accordance with the ability to accumulate energy, chemical sources are divided into primary, backup, secondary and electrochemical generators. There is also a current source using a field-effect transistor. Each type should be considered in more detail.
Primary current source
Such sources allow only one-time use of the chemical energy of the reagents. The cathode (positive electrode) and anode (negative electrode) are separated in a liquid or paste state by an electrolyte. Both the cathode and the anode have a galvanic connection with each other.
Secondary current source
Such batteries or rechargeable batteries allow the repeated use of chemical energy, from hundreds of times to tens of thousands of cycles. The electrolyte and electrodes are constantly in a state of electrical contact with each other. To date, specific storage conditions for such batteries have been developed.
Backup current source
Although standby sources allow only one cycle, the electrolyte and electrodes are not galvanically connected. They are stored either in a liquid state (in metal or glass ampoules) or in a hard solid state.
