When designing electrical systems, it is necessary to competently operate with such values \u200b\u200bas amperes, watts and volts. In addition, you need to be able to correctly calculate their ratio during the load on this or that mechanism. Yes, of course, there are systems in which the voltage is fixed, for example, a home network. However, it is not necessary to forget that the strength and power of the current are still different concepts, so you need to know exactly how much watts contains 1 amp.
Is there a difference between volts and watts?
To begin with, let's remember that they denote these concepts. And also let's try to find out if there is a significant difference between them.
So, the electrical voltage producing the current whose strength is 1 amp called volts. It should be noted that it "works" in the conductor with resistance of 1 Ohm.
Volt can be divided:
- 1 000 000 microvolt
- 1,000 Millivolt
At the same time, it can be said that Watt is the constant power of the electric current. At voltage of 1 volt, its strength is 1 amper.
Based on the foregoing, we can safely argue that the difference between these concepts is still there. Consequently, when working with various electrical systems it is necessary to take into account.
What is ampere?
There is a generally accepted division according to which 1 A contains:
- 1 000 000 microamper
- 1,000 ml.
How many volts contains 1 amp?
Answer this question is quite difficult. However, in order for you to make it easier to deal with this issue, we suggest you familiarize yourself with the relationship tables:
For DC:
For alternating current:
What is Volt amperes and how to translate them to Watta?
Another unit of power measurement adopted in C is a volt-amp (VA). It is equal to the product of such valid values \u200b\u200bas current and tension.
Additionally, it is worth noting that as a rule, WA is used exclusively in order to estimate the power in alternating current connections. That is, in cases where Watt and Volt-ampere is a different meaning.
Currently, there are many different online calculators that allow you to quickly and easily translate VAT. This procedure is so simple that we will not stop our attention on it.
But, especially for those people who do not have an online calculator for the translation of the Volt-Ampere in Watta, we consider the process of translation These quantities in more detail:
With this formula, we can find out current strength. Of course, only if we are already tension and power are known..
That is, it turns out that to recalculate watts in amps, we must figure out the voltage in the system. For example, in the US, the voltage in the power grid is 120V, and in Russia - 220V.
It should be noted that the batteries or batteries used in cars typically have a voltage equal to 12 V. A voltage in small batteries used for various portable devices, as a rule, does not exceed 1.5 V.
Thus, we can say that knowing the voltage and power, we can easily learn also and current strength. For this we need only right take advantage of the above formula.
Let's look at how it "works" on a specific example: if the voltage is 220V and the power is 220W, the current will be 220/220 or 1 A.
How many watts in 1 ampere?
Now let's try to transfer watts to amps. And for this we will need another formula:
In it, I is a, p - watt, and u - volts.
By producing a simple calculation for this formula, we can find out how long W in one A.
As we said earlier, there is another way to calculate how much watts in 1 A. In order to take advantage of them you will need open online calculator And enter in it consumed power, as well as voltage.
Further, you just need to click on the button with the inscription "Calculate" and during a couple of seconds a special program will give you the right value. Taking advantage of this way, you will undoubtedly save your time and strength, since you do not have to independently calculate all the indicators using formulas.
We owe the current comfort of our life that is electric current. It illuminates our dwellings, generating radiation in the visible range of light waves, it prepares and heats up food in a variety of devices like electric shock, microwave ovens, toasters, eliminating us from the need to search for a fuel for a fire. Thanks to him, we quickly move in the horizontal plane in the electricals, metro and trains, move in the vertical plane on escalators and in the elevator cabins. We are obliged to heat and comfort in our dwellings, which flows in air conditioners, fans and electrical heaters. A variety of electric electric shock machines facilitate our work, both in everyday life and production. Truly we live in the electric age, since it is thanks to electric current our computers and smartphones, Internet and television, and other smart electronic devices work. No wonder humanity is so much effort to generate electricity on thermal, atomic and hydroelectric power plants - electricity itself is the most convenient form of energy.
No matter how paradoxically sounded, but the ideas of the practical use of electric current in one of the first to be adjacent to the most conservative part of society - the fleet officers. It is clear, it was difficult to get up in this closed caste, it was difficult to prove the admirals who started Jungi on a sailing fleet, the need to transition to all-metal ships with steam engines, so junior officers always made a bet on innovations. It is the success of the application of branders during the Russian-Turkish war in 1770, who have decided the outcome of the battle in the Chesmen Bay, raised the question of protecting ports not only by coastal batteries, but also more modern on that day means of protection - mine harnesses.
The development of underwater mines of various systems was carried out since the beginning of the 19th century, autonomous electricity operating mines became the most successful structures. In the 70s The 19th century, the German physicist Heinrich Herz was invented the device for electrical detonation of the anchor mines with depth of up to 40 m. Its modifications are familiar to us according to historical films on naval themes - this is the infamous "horned" mine in which the lead "Rog" Containing an ampoule filled with electrolyte was frozen at contact with the vessel housing, as a result of which the simplest battery began to work, the energies of which were enough to detonate mines.
The sailors were the first to estimate the potential then still imperfect powerful sources of light - modifications of candles of apple, in which an electric arc served as a source of light and a glowing sparkled positive coal electrode - for use in order to alarm and lighting the battlefield. The use of spotlights gave an overwhelming advantage to the side applied to night battles or simply using them as a means of alarm to transmit information and coordinate the actions of marine compounds. And lighthouses equipped with powerful spotlights simplified navigation in coastal dangerous waters.
It is not surprising that it was the fleet that accepted the ways of wireless transmission of information - sailors did not embarrass the large size of the first radio stations, since the premises of the ships allowed to place so perfect, although at that time and very cumbersome, communication devices.
Electrical machines helped to simplify the charging of ship cannons, and the electric power units of the turning towers raised the maneuverability of mawed shocks. The teams passed on the ship telegraph increased the efficiency of interaction between the entire team, which gave a considerable advantage in combat clasions.
The most terrifying use of electric current in the history of the fleet was the use of Radier diesel-electric submarines of class U Third Reich. The submarines of the "wolf flocks" of Hitler saw many vessels of the Allied Transport Fleet - enough to remember the sad fate of the convoy PQ-17.
British seamans managed to get several copies of Enigma encryption machines (riddle), and British intelligence successfully deciphered its code. One of the outstanding scientists who worked on this is Alan Turing, known as its contribution to the basics of informatics. Having access to the radio supports Admiral Mennie, the Allied Fleet and coastal aviation were able to drive the "wolf" back to the shores of Norway, Germany and Denmark, so the operations with the use of submarines from 1943 were limited by short-term raids.
Hitler planned to equip his submarines of FAu-2 missiles for attacks on the east coast of the United States. Fortunately, the rapid allies attacks in the Western and Eastern fronts did not allow these plans to be implemented.
The modern fleet is unthinkable without aircraft carriers and nuclear submarines, the non-volatility of which is ensured by atomic reactors that successfully combine the technology of the 19th century steam, the technology of the 20th century of electricity, and atomic technologies of the 21st century. Atomic reactors generate electric current in an amount sufficient to ensure the vital activity of the whole city.
In addition, the sailors again turned their attention to electricity and tested the use of railnotes - electric guns for firing by kinetic shells having a huge devastating force.
Historical reference
With the advent of reliable electrochemical sources of DC, developed by the Italian physicist Alessandro Volta, a whole pleiad of wonderful scientists from different countries engaged in the study of electric shock-related phenomena, and developing its practical application in many areas of science and technology. It is enough to recall the German scientist Georg Oma, which has formulated the law of current flow for the elementary electrical circuit; German physics of Gustav Robert Kirchhoff, which has developed methods for calculating complex electrical circuits; French physics Andre Marie Ampere who discovered the law of interaction for constant electric currents. The works of the English physics of James Prescott Joule and the Russian scientist Emil Christianovich Lenza, led, independently of each other, to the opening of the law of quantitative assessment of the thermal effect of electric current.
The further development of the study of the electric current properties was the work of the British physics of James Clark Maxwell, which laid the foundations of modern electrodynamics, which are now known as the Maxwell equations. Maxwell also developed an electromagnetic theory of light, predicting many phenomena (electromagnetic waves, electromagnetic radiation pressure). Later, German scientist Heinrich Rudolf Hertz experimentally confirmed the existence of electromagnetic waves; His work on the study of reflection, interference, diffraction and polarization of electromagnetic waves formed the basis of the creation of the radio.
The works of French physicists Jean-Batista Bio and Felix Savara, experimentally discovered manifestations of magnetism in the flow of DC, and the wonderful French mathematics of Pierre-Simon Laplace, who summarized their results in the form of mathematical patterns, for the first time tied two sides of one phenomenon, putting the beginning of electromagnetism. The relay from these scientists took the brilliant British physicist Michael Faraday, which opened the phenomenon of electromagnetic induction and placed the beginning of modern electrical engineering.
A huge contribution to the explanation of the nature of the electric current was made by the Netherlands Physico theorist Hendrik Anton Lorenz, which created a classic electronic theory and received an expression for the strength acting on a moving charge from the side of the electromagnetic field.
Electricity. Definitions
Electric current - directional (ordered) movement of charged particles. By virtue of this, the current is defined as the number of charges, which passed through the conductor section per unit of time:
I \u003d Q / T where q - charge in the coulons, t - time in seconds, I - current in ampere
Another determination of the electric current is associated with the properties of the conductors and is described by the Ohm law:
I \u003d u / r where u is voltage in volts, R - resistance in Omah, I - current in ampere
The electric current is measured in amperes (a) and its decimal multiple and dolle units - nanoamas (billion dollars of amperes, for), microampers (million dollars, MCA), milliamperes (thousandth share of amperes, Ma), kiloampers (thousands of amps, ka) and megahampers (millions of amps, MA).
Current dimension in the system system is defined as
[A] \u003d [CL] / [s]
Features of electric current flow in various environments. Physics phenomena
Electric current in solids: metals, semiconductors and dielectric
When considering the problem of the electric current, it is necessary to take into account the presence of different carriers of the current - elementary charges - characteristic of this physical condition of the substance. In itself, the substance may be solid, liquid or gaseous. A unique example of such states observed under normal conditions can serve as a monooxide dihydrogen, or, otherwise, hydroxide hydroxide, and simply ordinary water. We observe it with a solid phase, reaching the pieces of ice from the freezer for cooling drinks, the basis for most of which is water in a liquid state. And when welding tea or soluble coffee, we pour it with boiling water, and the readiness of the latter is controlled by the appearance of a fog consisting of water droplets, which is condensed in cold air from a gaseous water vapor coming out of the kettle's nose.
There is also a fourth state of a substance called plasma, from which the upper layers of stars, the ionosphere of the Earth, the flame, electric arc and the substance in fluorescent lamps consist. High-temperature plasma with difficulty is reproduced in the conditions of earth laboratories, since it requires very high temperatures - more than 1,000,000 K.
From the point of view of the structure, solid bodies are divided into crystalline and amorphous. Crystalline substances have an ordered geometric structure; Atoms or molecules of such a substance form peculiar volumetric or flat lattices; Crystal materials include metals, their alloys and semiconductors. The same water in the form of snowflakes (crystals of various non-repeating forms) perfectly illustrates the idea of \u200b\u200bcrystalline substances. Amorphous substances of the crystal lattice do not have; This structure is typical for dielectrics.
Under normal conditions, current in solid materials occurs due to the movement of free electrons generated from the valence electrons of atoms. From the point of view of the behavior of materials when electric current passing through them, the latter are divided into conductors, semiconductors and insulators. The properties of various materials according to the zone theory of conductivity are determined by the width of the forbidden zone in which electrons cannot be located. Insulators have the widest prohibited zone, sometimes reaching 15 eV. At an absolute zero temperature in insulators and semiconductors of electrons in the conduction zone there is no, but at room temperature there will already be a number of electrons knocked out of the valence zone due to thermal energy. In conductors (metals), the conduction zone and the valence zone overlap, therefore, at a temperature of absolute zero, there is a sufficiently large amount of electrons - current conductors, which is preserved at higher temperatures of materials, up to their complete melting. Semiconductors have small forbidden zones, and their ability to conduct an electric current strongly depends on temperature, radiation and other factors, as well as from the presence of impurities.
A separate case is considered to be the flow of electrical current through the so-called superconductors - materials having zero current flow resistance. The conductivity electrons of such materials form the particle ensembles associated with each other by quantum effects.
Insulators, as follows from their name, electric current is extremely poorly carried out. This property of insulators is used to limit the flow between the conductive surfaces of various materials.
In addition to the existence of currents in conductors with a constant magnetic field, in the presence of AC and the associated alternating magnetic field, there are effects associated with its change or so-called "vortex" currents, otherwise called Foucault currents. The faster the magnetic flux is changing, the stronger the vortex currents that do not flow on a certain paths in the wires, and, closing in the conductor, form the vortex contours.
The vortex currents exhibit the skin effect, which is reduced to the fact that the alternating electric current and magnetic flux are distributed mainly in the surface layer of the conductor, which leads to the loss of energy. To reduce the loss of energy to the vortex currents, the separation of alternating current magnetic cores is used to separate, electrically insulated, plates.
Electric current in liquids (electrolytes)
All fluids, to some extent, are able to carry out an electric current when the electrical voltage is applied. Such fluids are called electrolytes. The carriers of the current in them are positive and negatively charged ions - respectively, cations and anions that exist in the solution of substances due to electrolytic dissociation. The current in the electrolytes due to the movement of ions, in contrast to the current due to the movement of electrons characteristic of metals, is accompanied by the transfer of the substance to the electrodes with the formation of new chemical compounds near them or the precipitation of these substances or new connections on the electrodes.
This phenomenon laid the basis of modern electrochemistry, giving quantitative determination by gram equivalents of various chemicals, thereby turning inorganic chemistry into accurate science. Further development of electrolyte chemistry made it possible to create once charged and rechargeable sources of chemical current (dry batteries, batteries and fuel cells), which, in turn, gave a huge impetus in the development of equipment. It is enough to look under the hood of your car to see the results of the efforts of generations of scientists and chemist engineers in the form of a car battery.
A large number of current flow-based flow processes allows not only to give a spectacular type of final product (chrome and nickelock), but also to protect them from corrosion. The processes of electrochemical precipitation and electrochemical etching make up the basis of the production of modern electronics. Now these are the most sought-after technological processes, the number of components manufactured by these technologies is calculated by tens of billions of units per year.
Electric current in gases
The electric current in the gases is due to the presence of free electrons and ions in them. For gases, due to their rareness, a large length of the mileage is characterized before molecules and ion collisions; Because of this, current flow under normal conditions through them is relatively difficult. The same can be argued relative to the mixtures of gases. The natural mixture of gases is atmospheric air, which is considered a good insulator in electrical engineering. It is also characteristic of other gases and their mixtures under normal physical conditions.
The flow of current in the gases is very dependent on various physical factors, somehow: pressure, temperature, composition of the mixture. In addition, the action is provided by various kinds of ionizing radiation. For example, being illuminated by ultraviolet or X-rays, or under the action of cathode or anode particles or particles emitted by radioactive substances, or, finally, under the action of high temperature, the gases acquire a property better to carry out an electric current.
The endothermic process of ion formation as a result of energy absorption by electrically neutral atoms or gas molecules is called ionization. Having obtained enough energy, an electron or several electrons of an external electron shell, overcoming a potential barrier, leave an atom or molecule, becoming free electrons. Atom or gas molecule becomes positively charged with ions. Free electrons can be connected to neutral atoms or molecules, forming negatively charged ions. Positive ions can be captured by free electrons in a collision, becoming electrically neutral at the same time. This process is called recombination.
The passage of current through the gas medium is accompanied by a change in the state of the gas, which predetermines the complex nature of the current dependence on the applied voltage and, in general, is subject to the law of Ohm only at small currents.
There are disconnect and independent discharges in gases. With the poor discharge, the current in the gas exists only in the presence of external ionizing factors, with their absence there is no significant current in the gas in the gas. With an independent discharge, the current is maintained due to the impact ionization of neutral atoms and molecules when a collision with an accelerated electric field with free electrons and ions even after removing external ionizing influences.
A discharge discharge at a small value of the potential difference between the anode and the cathode in Gaza is called a quiet discharge. With increasing voltage, the strength of the current is first increasing in proportion to the voltage (section OA on the volt-amps characteristic of the quiet discharge), then the current is slowed down (section of the AV curve). When all particles that occurred under the action of the ionizer are leaving for the same time on the cathode and on the anode, the increase in current with increasing voltage does not occur (section of the Sun graph). With a further increase in voltage, the current increases again, and the quiet discharge goes into a non-admonishing avalanche. A variety of failed discharge is a glowing discharge that creates light in gas-discharge lamps of various colors and destination.
The transition of an independent electrical discharge in a gas in an independent discharge is characterized by a sharp increase in current (point E on a volt-amps curve). It is called electric gas supply.
All of the above types of discharges belong to the established types of discharges, the main characteristics of which are independent of time. In addition to the established discharges, there are uninstalled discharges that occur usually in strong inhomogeneous electric fields, for example, in pointed and curved surfaces of conductors and electrodes. There are two types of unspecified discharges: a crown and spark discharge.
With a corona discharge, ionization does not lead to a breakdown, it is simply a repeated process of igniting the indifferent discharge in a limited space near the conductors. An example of a corona discharge can be a glow of atmospheric air near high raised antennas, thunders or high-voltage power lines. The occurrence of the corona discharge on the power lines leads to loss of electricity. In former times, this glow on the tops of the mast was familiar to sailors of the sailing fleet as the lights of St. Elma. The coronary discharge is used in laser printers and electronic copiers, where it is formed by the Metal string, which is filled with high voltage. This is necessary for the ionization of the gas in order to apply charge to the photosensitive drum. In this case, the crown discharge benefits.
A spark discharge, in contrast to the crown, leads to a breakdown and has a form of intermittent bright branching, filled with ionized gas-channels, arising and disappearing, accompanied by the release of a large amount of heat and a bright glow. An example of a natural spark discharge can be lightning, where the current can reach values \u200b\u200bin tens of kiloamper. The formation of the lightning itself is preceded by the creation of a conduction channel, the so-called downward "dark" leader, forming a conductive channel with an induced ascending leader. Lightning is usually a multiple spark discharge in the formed conduction channel. Powerful spark discharge found its technical use also in compact photo list, in which the discharge occurs between the electrodes of the quartz glass tube filled with a mixture of ionized noble gases.
A long-term supported gas band is called an arc discharge and is used in welding machinery, which is the cornerstone of technologies for creating steel structures of our time, from skyscrapers to aircraft carriers and cars. It is used both for welding and for cutting metals; The difference in the processes is due to the strength of the current current. With relatively smaller values \u200b\u200bof the current, the metal welding occurs, with higher values \u200b\u200bof the arc discharge current - there is a cutting of a metal due to the removal of the molten metal from under the electrical arc by various methods.
Another use of arc discharge in gases serve gas-discharge lighting lamps that accelerate darkness on our streets, squares and stadiums (sodium lamps) or car halogen lamps, which have now replaced conventional incandescent bulbs in the car headlights.
Electric Current in Vacuum
The vacuum is an ideal dielectric, so electric current in vacuo is possible only in the presence of free carriers in the form of electrons or ions, which are generated by thermal or photoemission, or other methods.
The main method of producing current in vacuum due to electrons is the method of thermoelectronic electron emission metals. Around the heated electrode, called the cathode, is formed a cloud of free electrons, which ensure the flow of electric current in the presence of a second electrode, called the anode, under the condition of the presence between them the corresponding voltage of the required polarity. Such electrovacuum devices are called diodes and have the property of one-sided current conductivity, locked with reverse voltage. This property is used to straighten the AC transformed by the system from diodes into a pulsed current of a permanent direction.
Adding an additional electrode called a grid located near the cathode allows to obtain an amplifying element of a trigger in which small changes in the voltage on the grid relative to the cathode make it possible to obtain significant changes in the flowing current, and, accordingly, significant changes in the stress on the load included in series with a lamp relative to the power supply As used to enhance various signals.
The use of electrovacuum devices in the form of triiodas and instruments with a large number of grids for various purposes (tetrodov, pentoders and even hepodes), produced a revolution in generating and enhancing radio frequency signals, and led to the creation of modern radio and television systems.
Historically, the first was the development of radio broadcasting, since the methods of transformation relative to low-frequency signals and their transmission, as well as the circuitry of the receiving devices with amplification and transformation of the radio frequency and the transformation into an acoustic signal was relatively simple.
When creating television to convert optical signals, electrovacuum devices were used - iconoscopes, where the electrons were emissive due to the photoemission from the incident light. Further signal amplification was performed by amplifiers on electronic lamps. For reverse conversion of the television signal, kinecopes served, giving an image due to the fluorescence of the screen material under the influence of electrons, accelerated to high energies under the influence of accelerating voltage. Synchronized system of reading iconkop signals and a kinescope image expandment system created a television image. The first kinescopes were monochrome.
In the future, color television systems were created, in which the reading image iconoscopes react only to its color (red, blue or green). The radiating elements of the kinescope (color phosphor), due to the flow of current produced by the so-called "electron guns", responding to the accelerated electrons in them, emitted light in a certain range of appropriate intensity. In order for the rays from the guns of each color to their phosphor, they used special shielding masks.
Modern television and broadcasting equipment is performed on more progressive elements with less power consumption - semiconductors.
One of the widespread methods for obtaining an image of the internal organs is the X-ray method, in which the electrons emitted by the cathode receive such a significant acceleration that X-ray radiation can be generated during the anode, capable of penetrating through the soft tissues of the human body. Radiographs are in the hands of physicians, unique information about damage to the bones, the state of the teeth and some internal organs, even identifying such a formidable disease as lung cancer.
In general, electrical currents formed as a result of electron movement in vacuum have a wide range of applications to which all radiol vias belong, accelerators of charged particles, mass spectrometers, electronic microscopes, vacuum generators of ultra-high frequency, in the form of a traveling wave lamps, clusterons and Magnetronov. It is Magnetron, by the way, heated or prepare food in microwave ovens.
Last time recently has technology of application of film coatings in vacuo, which play the role of both protective and decorative and functional coating. Coatings and their alloys are used as such coatings, and their compounds with oxygen, nitrogen and carbon. Such coatings change the electrical, optical, mechanical, magnetic, corrosive and catalytic properties of the surfaces coated, or several properties are combined.
The complex chemical composition of coatings can be obtained only using the ionic spraying technique in vacuo, the species of which are cathode spraying or its industrial modification - magnetron spraying. Ultimately it is electric current Due to the ions, the deposition of components on a precipitated surface, giving it new properties.
It is in this way that the so-called ionic reactive coatings (nitride films, carbides, metal oxides) can be obtained with a complex of extraordinary mechanical, thermophysical and optical properties (with high hardness, wear resistance, electric and thermal conductivity, optical density), which cannot be obtained by other methods .
Electric Current in Biology and Medicine
Knowing the behavior of currents in biological objects gives a powerful method of research, diagnosis and treatment in the hands of biologists and physicians.
From the point of view of electrochemistry, all biological objects contain electrolytes, regardless of the characteristics of the structure of this object.
When considering current flow through biological objects, their cellular structure must be taken into account. An essential element of the cell is a cell membrane - an outer shell, a fencing cell from the effects of adverse environmental factors due to its election permeability for various substances. From the point of view of physics, the cell membrane can be imagined as a parallel compound of the condenser and several chains from the connected current source and resistor. This predetermines the dependence of the electrical conductivity of biological material from the frequency of the supplied voltage and the shape of its oscillations.
The biological tissue consists of cells of the organ itself, the intercellular fluid (lymph), blood vessels and nerve cells. The latter in response to the effects of electric current are responding with excitation, forcing the muscles and blood vessels of the animal to decline and relax the muscles. It should be noted that the flow of current in biological tissue is non-linear.
An experiments of an Italian doctor, anatoma, physiologist and physics of Luigi Galvania, who became one of the founders of electrophysiology, can serve as a classic example of exposure to electric current on the biological object. In his experiments, the transmission of electric current through the nerves of the frog legs led to a reduction in muscles and twisting the legs. In 1791, the famous discovery was described in the "Treatise on Electricity forces with Muscular Movement". The phenomena, open galvania, for a long time in textbooks and scientific articles were called "galvanism." This term and dynamine is maintained in the name of some devices and processes.
Further development of electrophysiology is closely connected with neurophysiology. In 1875, independently of each other English surgeon and physiologist Richard Katon and Russian physiologist V. Ya. Danilevsky showed that the brain is a generator of electrical activity, that is, brain biotoks were opened.
Biological objects during their livelihoods create not only microcurrents, but also high stresses and currents. Significantly earlier electroplating Anata John Walsh proved the electric nature of the strike of the skate, and the Scottish surgeon and Anatas John Hunter gave an accurate description of the electrical organ of this animal. Walsh and Hunter studies were published in 1773.
In modern biology and medicine, various methods of research of living organisms are applied, both invasive and non-invasive.
A classic example of invasive methods is a laboratory rat with a bundle of the electrodes burned into the brain, running in labyrinths or decisive other tasks set by scientists.
Non-invasive methods include such familiar research as the removal of a encephalogram or an electrocardiogram. At the same time, the electrodes, reading biotoks of the heart or brain, remove the currents directly from the skin of the surveyed. To improve contact with electrodes, the skin is wetted by saline, which is a good conductive electrolyte.
In addition to the use of electric current during scientific research and technical control of the state of various chemical processes and reactions, one of the most dramatic moments of its application, known to the general public, is the launch of the "stopped" heart of a hero of the modern film.
Indeed, the flow of a short-term pulse of a significant current only in isolated cases is able to launch the stopped heart. Most often, its normal rhythm is restored from the state of chaotic convulsive contractions, called heart fibrillation. Instruments used to restore the normal rhythm of heart cuts are called defibrillators. The modern automatic defibrillator removes the cardiogram itself, determines the fibrillation of the ventricles of the heart and independently decides - to beat the current or not to beat - can be enough to skip a small trigger pulse through the heart. There is a tendency to establish automatic defibrillators in public places, which can significantly reduce the number of deaths due to an unexpected heart stop.
The practitioners of emergency practitioners do not have any doubt about the use of the defibrillation method - trained quickly determine the physical condition of the patient in the cardiogram, they make a solution much faster than the automatic defibrillator intended for the general public.
Immediately it will be appropriate to mention the artificial drivers of the heart rhythm, otherwise called with cardiosimulants. These devices are implanted under the skin or under the thoracic muscle of the person, and such a device through the electrodes submits to myocardium (heart muscle) current pulses with a voltage of about 3 V, stimulating the normal operation of the heart. Modern electrocardial movements are able to provide uninterrupted work for 6-14 years.
Electric current characteristics, its generation and application
Electric current is characterized by the size and shape. According to its behavior, over time, there is a permanent current (not changing over time), aperiodic current (arbitrarily changing over time) and alternating current (varying over time according to a certain, as a rule, periodic law). Sometimes to solve various tasks, the simultaneous presence of direct and alternating current is required. In this case, they are talking about alternating current with a constant component.
Historically, a tribelectric current generator appeared first, which produced the current due to the friction of wool about a piece of amber. More advanced current generators of this type are now called Van de Grafa generators, by the name of the inventor of the first technical solution of such machines.
As mentioned above, the Italian physicist Alessandro Volta was invented by an electrochemical DC generator, which became the predecessor of dry batteries, batteries and fuel cells, which we use and so on, as convenient sources of current for a variety of devices - from wrist watch and smartphones to just automotive batteries and traction batteries TESLA electric vehicles.
In addition to these direct current generators, there are current generators on the direct nuclear decay of isotopes and magnetohydrodynamic generators (MHD generators) of the current, which still have limited use by virtue of their low-capacity, weak technological basis for widespread applications and for other reasons. However, radioisotope energy sources are widely used where complete autonomy needs: in space, on deep-water devices and hydroacoustic stations, on lighthouses, buoy, as well as in the extreme north, in the Arctic and Antarctic.
In electrical engineering, current generators are divided into direct current generators and alternate current generators.
All these generators are based on the phenomenon of electromagnetic induction, open by Michael Faraday in 1831. Faradays built the first low-power unipolar generator, giving a constant current. The first alternator was proposed an anonymous author under Latin initials R.M. In a letter to Faraday in 1832. After publishing a letter, Faraday received a letter of thanks from the same anonym with an improved generator scheme in 1833, in which an additional steel ring (yarm) was used to close the magnetic streams of windings cores.
However, at that time, there was still no use for alternating current, since for all practical applications of electricity of that time (mine electrical engineering, electrochemistry, which has just originated electromagnetic telegraph, the first electric motors) was required permanent current. Therefore, subsequent inventors sent their efforts to build generators giving a constant electric current, developing various switching devices for these purposes.
One of the first generators who received practical application was a magnetoelectric generator of the Russian academician B. S. Yakobi. This generator was adopted by the electroplating teams of the Russian army, who used it to ignite mine fans. Improved modifications of the Jacobi generator are still used to remotely actuate mine charges, which has found a wide display in military historical films in which the saboteurs or partisans undermine bridges, trains or other objects.
In the future, the struggle between the generation of direct or alternating current with varying success was carried out among the inventors and practitioner engineers, which led to the apogee confrontation of titans of modern electric power industry: Tomas Edison with General Electric, on the one hand, and Nikola Tesla with Westinghouse, on the other hand. The powerful capital, and the development of Tesla in the field of generation, transmission, and the transformation of the AC electric current became the national domain of American society, which, to a large extent, later contributed to the US technological dominance.
In addition to the actual generation of electricity for a variety of needs based on the transformation of mechanical movement to electricity, due to the reversibility of electrical machines, the possibility of reverse transformation of the electrical current into the mechanical movement implemented by DC and AC electric motors has appeared. Perhaps these are the most common machines of modernity, including starters of cars and motorcycles, drives of industrial machines and a variety of household devices. Using various modifications of such devices, we have become masters for all hands, we can strict, saw, drill and mill. And in our computers, thanks to the miniature precision DC motors, the drives of rigid and optical disks are spinning.
In addition to the usual electromechanical engines, ion engines that use the principle of reactive movement in the emission of accelerated ions of the substance are operated, while they are mainly used in outer space on small satellites to excrete them into the necessary orbits. And photon engines of the 22nd century, which exist so far only in the project and which will carry our future interporey ships with subsettle speed, most likely will also work on electric current.
To create electronic elements and when growing crystals of various purposes, for technological reasons requires super-sufficient DC generators. Such precision DC generators on electronic components are called current stabilizers.
Electric current measurement
It should be noted that the instruments for measuring the current (microammeters, milliammeters, ammeters) are very different from each other primarily by the type of structures and the principles of action - these can be DC devices, alternating current of the low frequency and alternating current of high frequency.
On the principle of operation, electromechanical, magnetoelectric, electromagnetic, magnetodynamic, electrodynamic, induction, thermoelectric and electronic devices are distinguished. Most switching devices for measuring currents consists of a combination of a movable / stationary frame with a wound coil and fixed / movable magnets. Due to such a design, a typical ammeter has an equivalent circuit of consistently connected inductance and resistance to the capacitance. Because of this, the frequency response of the shooting ampermers has a challenge at high frequencies.
The basis for them is the miniature galvanometer, and the various measurement limits are achieved by using additional shunt - resistors with a low resistance, which is for orders below the resistance of the measuring galvanometer. Thus, on the basis of one device, devices can be created for measuring currents of various ranges - microammeters, milliammeters, ammeters, and even kiloammeters.
In general, in measuring practice, the behavior of the measured current is important - it can be a time function and have a different form - to be a permanent, harmonic, non-harmonic, impulse, and so on, and its value is made to characterize the modes of work of radio engineering chains and devices. Distinguish the following current values:
- instant
- amplitude
- average,
- rMS (acting).
Instant current i i - is the current value at a certain point in time. It can be observed on the screen of the oscilloscope and determine for each point in time by the oscillogram.
Amplitude (peak) The current value i M is the largest instantaneous value of the current for the period.
The average quadratic (acting) current value i is defined as the root square from the average for the period of the square of the instantaneous current values.
All switching ammeters are usually graded in the range of current values.
The average value (constant component) of the current is the arithmetic average of all its instantaneous values \u200b\u200bduring the measurement time.
The difference between the maximum and minimum values \u200b\u200bof the signal current is called the scope of the signal.
Now, mainly, for measuring the current, both multifunctional digital devices are used and oscilloscopes - not only appears on their screens. the form Voltage / current, but also the essential characteristics of the signal. Such characteristics also includes the frequency of changes in periodic signals, so the frequency limit of measurements of the instrument is important in the measurement technique.
Measuring current with oscilloscope
An illustration to the above will be a series of experiments on measuring the acting and peak value of the current of sinusoidal and triangular signals using a signal generator, an oscilloscope and a multifunctional digital device (multimeter).
The overall scheme of experiment No. 1 is presented below:
Signal generator (FG) is loaded to a sequential connection of the multimeter (MM), the resistance of the shunt R s \u003d 100 Ohms and the load resistance R in 1 com. OS oscilloscope is connected parallel to the resistance of the shunt R s. The resistance value of the shunt is selected from the condition R s< Let's apply for the load resistance of the sinusoidal form from the generator with a frequency of 60 hertz and 9 volts amplitude. Press the very convenient AUTO SET button and will monitor the signal on the screen shown in Fig. 1. The scope of the signal is about five large divisions at the price of 200 mV division. The multimeter shows the current value of 3.1 mA. The oscilloscope determines the range of signal voltage at the measuring resistor U \u003d 312 mV. The current current value through the R S resistor is determined by the law of the Ohm: I rms \u003d u rms / r \u003d 0.31 V / 100 ohm \u003d 3.1 mA, what corresponds to the indications of the multimeter (3.10 mA). Note that current scope through our chain from the included sequentially two resistors and a multimeter is equal to I p-p \u003d u p-p / r \u003d 0.89 V / 100 ohm \u003d 8.9 mA It is known that the peak and acting values \u200b\u200bof the current and voltage for the sinusoidal signal differ in √2 times. If you multiply i rms \u003d 3.1 mA per √2, we get 4.38. You will double this value and we get 8.8 mA, which almost corresponds to the current measured by oscilloscope (8.9 mA). Reduced signal from the generator twice. The scope of the image on an oscilloscope will decrease exactly approximately twice (464 mV) and the multimeter will show an approximately reduced twice value of the current 1.55 mA. We define the indications of the current current value on the oscilloscope: I rms \u003d u rms / r \u003d 0.152 V / 100 ohms \u003d 1.52 mA, that approximately corresponds to the indications of the multimeter (1.55 mA). Running the generator frequency up to 10 kHz. In this case, the image on an oscilloscope will change, but the signal is the same as the same, and the multimeter readings will decrease - the permissible working frequency range of the multimeter affects. Let's return to the initial frequency of 60 hertz and voltage 9 in the signal generator, but change form Its signal with sinusoidal on triangular. The scope of the image on the oscilloscope remained the same, and the indications of the multimeter decreased compared with the value of the current, which it showed in Experiment No. 1, since the active value of the signal current has changed. The oscilloscope also shows a decrease in the range of the voltage measured on the resistor R s \u003d 100 ohms. Homemade pedestal rack with full-featured televisophile and monitors for home video studio In order to answer this, in general, a simple question, we need to briefly consider such physical quantities once again such as the current (A), voltage (B) and power (W). They are very closely related to each other and cannot exist without each other. It is well known that the creation and maintenance of electric current depends entirely on the electric field. Directly depends on the magnitude of the electric field. For a better understanding of this dependence, let's try to characterize these concepts in quantitative terms. The power of the current is not a completely successful name for this process. It appeared at the time when it was not quite clear what it was. After all, this is not at all the force, as such, and the number of electrons (electricity), which flows through the cross section of the conductor in one second. This magnitude could be displayed as the number of electrons passing through the conductor per second. However, the electron charge is a very small value. It is not suitable for use in practice. For example: Through the filament of the incandescent light bulb of a conventional pocket flashlight in one second passes 2x1018Electrons. Therefore, the unit of measuring the magnitude of the electric charge began to be considered a charge that has 6.25x1018 electrons. This charge received the name pendant. Therefore, the unit is finally considered to be such a current at which a charge of 1 pendant passes through the cross section of the conductor in one second. Such a unit was named ampere To this day, used in electrical engineering to measure the current force. In order to determine the dependence of the electric current from the electric field, it is necessary to measure the field value. After all, the field is a force that acts on any charge, an electron, or pendant. It is the presence of such strength and is characteristic of an electric field. It is very difficult to measure the field strength, because in different places of the conductor it is unequal. It would have to carry out a large number of difficult measurements at different points. In this regard, the field value is characterized by no power acting on charges, but by the work performed by it, when moving one coulon from one end of the conductor to another. The operation of the electric field is called voltage. It also calls the difference in potentials (+ and -) at the ends of the conductor. Unit called voltage volt. Thus, it can be concluded that the concept of electric current is characterized by two main values: the current is directly the electric current, the voltage is the field value at which the current itself is created. It turns out that the force directly depends on the voltage. And finally, briefly consider what power is. We already know that U (voltage) is the work that is performed when moving 1 of the coulon. I is the current strength, or the number of pendants passing in one second. Thus, I x U is an indicator of full work performed in 1 second. In fact, this is the power of the electric current. Power measurement unit is watt. Watt \u003d ampere x volt or p \u003d i x u Amp \u003d watts / volt or i \u003d p / u 4.6 amp \u003d 1000W / 220V 2.7 amp \u003d 600W / 220V 1.8 amp \u003d 400W / 220V 1.1 amp \u003d 250W / 220V
Choose in the store two things that should be used "in tandem", for example, iron and outlet, and suddenly face the problem - "Electroparameters" on the marking are indicated in different units. How to choose the appliances and devices suitable to each other? How do amps translate to watta? Immediately I must say that it is impossible to do direct translation of units, because they denote different values. Watt - indicates power, i.e. The speed at which energy is consumed. Ampere is a unit of force talking about the current speed through a concrete section. In order for the electrical systems to work correctly, the ratio of amps and watts can be calculated at a certain voltage in the power grid. Last - measured in volts and maybe: Taking into account this, the indicators are compared. Knowing, in addition to the values \u200b\u200bof power and strength, also the voltage indicator, to translate amps in watts by the following formula: At the same time, P is power in watts, I is the current strength in amperes, U is voltage voltage. Online calculator In order to constantly be "in the subject", it is possible to create "amper-watt" -table with the most common parameters (1a, 6a, 9a, etc.). Such a "ratio schedule" will be reliable for networks with fixed and constant voltage. To calculate the variable voltage in the formula, another value is included - the power factor (km). Now she looks like this: Making the process of transferring units to the measurement will be more rapid and simple to help such an affordable tool as an Amp in Watta online calculator. Do not forget that if you need to enter a fractional number in the graph, it is performed through the point, and not through the comma. Thus, to the question "1 watt - how many amps?", Using the calculator, you can give an answer - 0.0045. But it will be fair only for standard voltage in 220V. Using the calculators and tables presented on the Internet, you can not suffer over the formulas, and it is easy to compare different units of measurement. This will help you choose circuit breakers for different loads and not worrying for your household appliances and wiring condition. Ampere - Watt Table: Every time, going on vacation or business trip you have to take with you a whole heap of charging for various devices. I recently acquired a compact Xiaomi charger for 4 ports, a total outstanding power of 35W (7 amp) or 2.4 amps per port. Charging turned out to be very high quality and fully corresponds to the declared characteristics, so I decided to share information. Video Review with Load Testing Small packaging with MI logo, the main characteristics are indicated on one of the sides: Included: Charger and Instructions in Chinese. Sizes are very compact, it quietly fits in the hand, it will not take a lot of space on the trip. On the front part there are 4 USB ports. QC2.0 or QC3.0 support no, but the maximum current of 2,4A to the port and without it will quickly charge your smartphone or tablet. Folding fork and hidden into the case. The disadvantage can be considered that it is Chinese and additionally need to use an adapter that is not put into the kit. If you use the charge of the house, on a permanent basis, the design comes out rather cumbersome: adapter + charging + cable. Although I adapted her and at home, just put on the side and everything looks rather civilized. On trips, this question does not matter at all. But of course the most interesting and main question - compliance with the stated characteristics. Before you write a review, I used her at home for more than a month as the main one for charging his gadgets. In the work showed itself well - it does not heat, not noise. The fact that I did not write the review earlier is also associated with the fact that I waited for a new load for accurate measurements of charging capabilities. Here a couple of days ago I received, but the Chinese lay "pig" - the load turned out to be inoperative ... I had to use the old, which in principle no worse, but the step in which you can change the load is 0.5a, which does not accurately calculate the maximum potential of the charger. But what is that is, I will test on it. First of all, we learn how much the charger can give in reality to 1 port. Let's start with gradual load - 0,5A: 1a (actually the load consumes a little less - 0,95a) 2a (Real Load Consumption 1,88A) And 2,5A (achieved by using 1,88A and additional flashlight on 0,6A) As you can see the stated characteristics correspond to and even more. With the claimed 2,4A, the charger gives 2,5A without significant drawdown in voltage. But if you load even more, for example, on 3a, it no longer copes - the current is almost not growing, and the voltage sends. MI5S smartphone consumes 1,75a Smartphone Gemini consumes 1,43a Now turn on it all at the same time along with the load. Total in sum: 1.79a + 1,75a + 1.43a + 2,5A \u003d 7.47A. This is even higher than the stated features. Voltage seats up to 5.05V - 5.07V But charging holds the load. After 5 minutes, it is already greatly warm and I decide not to torment it, because it is still not designed for such work. Literally slightly slightly loaded when the smartphone has become slightly charged and began to take 1a (reducing the load on 0,5A) Immediately we see the voltage increase to 5.15V - 5.2V, which is already quite good. As a result, the stated characteristics fully confirmed.I consider the charger to consider high-quality and I recommend to the acquisition.Experience 1.
Experience 2.
Experience 3.
Experience 4.
Safety in current and voltage measurement
Electric field dependence
Measurement of the Power Power
What is power
How to translate watta to amps
As a visual example, you can consider this option.
Adjacent but different
"Fixed" translation
"Variable nuances"
6
12
24
48
64
110
220
380
Volt
5 watt
0,83
0,42
0,21
0,10
0,08
0,05
0,02
0,01
Ampere
6 watt
1
0,5
0,25
0,13
0,09
0,05
0,03
0,02
Ampere
7 watt
1,17
0,58
0,29
0,15
0,11
0,06
0,03
0,02
Ampere
8 watt
1,33
0,67
0,33
0,17
0,13
0,07
0,04
0,02
Ampere
9 watt
1,5
0,75
0,38
0,19
0,14
0,08
0,04
0,02
Ampere
10 watt
1,67
0,83
0,42
0,21
0,16
0,09
0,05
0,03
Ampere
20 watt
3,33
1,67
0,83
0,42
0,31
0,18
0,09
0,05
Ampere
30 watt.
5,00
2,5
1,25
0,63
0,47
0,27
0,14
0,03
Ampere
40 Watt
6,67
3,33
1,67
0,83
0,63
0,36
0,13
0,11
Ampere
50 watt
8,33
4,17
2,03
1,04
0,78
0,45
0,23
0,13
Ampere
60 Watt.
10,00
5
2,50
1,25
0,94
0,55
0,27
0,16
Ampere
70 Watt.
11,67
5,83
2,92
1,46
1,09
0,64
0,32
0,18
Ampere
80 watt
13,33
6,67
3,33
1,67
1,25
0,73
0,36
0,21
Ampere
90 Watt.
15,00
7,50
3,75
1,88
1,41
0,82
0,41
0,24
Ampere
100 watt
16,67
3,33
4,17
2,08
1,56
,091
0,45
0,26
Ampere
200 watt
33,33
16,67
8,33
4,17
3,13
1,32
0,91
0,53
Ampere
300 watt
50,00
25,00
12,50
6,25
4,69
2,73
1,36
0,79
Ampere
400 watt
66,67
33,33
16,7
8,33
6,25
3,64
1,82
1,05
Ampere
500 watt
83,33
41,67
20,83
10,4
7,81
4,55
2,27
1,32
Ampere
600 watt
100,00
50,00
25,00
12,50
9,38
5,45
2,73
1,58
Ampere
700 watt
116,67
58,33
29,17
14,58
10,94
6,36
3,18
1,84
Ampere
800 watt
133,33
66,67
33,33
16,67
12,50
7,27
3,64
2,11
Ampere
900 watt
150,00
75,00
37,50
13,75
14,06
8,18
4,09
2,37
Ampere
1000 watt
166,67
83,33
41,67
20,33
15,63
9,09
4,55
2,63
Ampere
1100 watt
183,33
91,67
45,83
22,92
17,19
10,00
5,00
2,89
Ampere
1200 watt
200
100,00
50,00
25,00
78,75
10,91
5,45
3,16
Ampere
1300 watt
216,67
108,33
54,2
27,08
20,31
11,82
5,91
3,42
Ampere
1400 watt
233
116,67
58,33
29,17
21,88
12,73
6,36
3,68
Ampere
1500 watt
250,00
125,00
62,50
31,25
23,44
13,64
6,82
3,95
Ampere
