What is electricity? Information about electric current. Getting and using electricity

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  Inner nature these interactions are still unknown, so we can only recognize objective reality- some bodies have the ability to interact with each other just like “pieces of amber rubbed with wool.”
  Of course, since Ancient Greece our knowledge of the world around us has expanded incredibly. We know that all bodies consist of molecules, molecules consist of atoms, atoms consist of electrons and nuclei, nuclei consist of protons and neutrons, protons and neutrons consist of... However, we can stop there for now, we have already returned to the electron , but not to a “piece” of amber, but to the smallest elementary particle capable of interacting with some other particles just like “pieces of amber rubbed with wool.”

35.1 Two types of electric charges.

If some particles (or bodies) have the ability to take part in electrical interactions, then it makes sense to attribute to them some characteristic that will indicate this property. This characteristic is called electric charge. Bodies taking part in electrical interactions are called charged. Thus, the term "electrically charged" is synonymous with the expression "participates in electrical interactions." Why some elementary particles have an electric charge and others do not - no one knows!
  Further reasoning, based on experimental data, is intended to specify this characteristic and, if possible, make it quantitative.
  The history of the study of electrical phenomena is long and full of drama,...
  Next we describe a series simple experiments which can be done at home “in the kitchen” or in the school laboratory. In explaining them, we will use the knowledge that has been obtained by many scientists over several hundred years, as a result of numerous and varied experiments.
  Now, we will reproduce in a very simplified form some of the steps experimental research, the conclusions from which served as the basis modern theory electrical interactions.
  To carry out experiments, first of all, you should learn how to obtain charged bodies. The simplest method achieving this goal is electrification by friction. For example, glass is well electrified (that is, acquires an electric charge) if rubbed with silk. The appearance of an electric charge manifests itself in the fact that such a stick begins to attract pieces of paper, hairs, dust particles, etc.
  It can also be established that many other substances are also electrified through friction. Knowing the result in advance, we will choose an ebonite stick rubbed with wool as the second “source” of electricity. Let's call the electric charge that appears on the glass “glass”, and the charge on ebonite “resin 2”.

Charles François Dufay (Charles François de Cisternay du Fay; 1698 - 1739) - French scientist, physicist, member of the Paris Academy of Sciences (fig.).
  Dufay achieved greatest success in systematizing information on electrical effects. He compiled a program for studying electrical phenomena and as a result discovered two types of electric charge: “glass” and “resin” (now they are called positive and negative); was the first to study electrical interactions and proved that similarly electrified bodies repel each other, and oppositely electrified bodies attract each other. In his experiments, Dufay no longer used an electroscope, but an electrometer, which made it possible to measure the amount of charge. To detect and measure electricity primitively, he used Hilbert's versor, making it much more sensitive. The first one electrified the human body and “received” electric sparks from it. He first expressed the idea of ​​the electrical nature of lightning and thunder (1735). Investigated magnetic phenomena, phosphorescence, birefringence in crystals.   Next, we need a “device” that could respond to the presence of an electric charge. To do this, hang a light glass twisted from a piece of foil on a thread. It is easy to check that this glass is not charged - no matter how much we bring a pencil, hand, physics textbook, etc. to it, no effect appears on the glass.
  Let's bring a charged glass electric rod to the uncharged glass (Fig. 217). The glass is attracted to it, like other small bodies. According to the angle of thread deflection (at known to the masses cup and the length of the thread) you can even calculate the force of attraction. If the glass does not come into contact with a charged stick, it remains uncharged, which can be easily verified experimentally. If the glass touches a charged stick, it will sharply push away from it. If you now remove the stick, the cup will be charged, which can be checked by bringing another uncharged body. For example, it will be attracted to the raised hand.


rice. 217
  Similar results are obtained if you replace a glass rod rubbed on silk with an ebonite rod rubbed on wool.
  Thus, in these experiments the difference between "glass" and "resin" electricity does not appear.

For now, we will not discuss why an uncharged glass is attracted to a charged stick, and a charged glass is attracted to an uncharged hand. The only conclusion we can draw from the experiment is that as a result of contact, the cup acquired an electric charge. Therefore, electric charge can be transferred from one body to another.
Let's take two identical foil cups and hang them next to each other on threads of the same length. If the cups are charged equally (either using a glass or an ebonite rod), then the cups repel (Fig. 218).


rice. 218
If the cups are charged with different charges, then they attract.
  Thus, we prove that there are at least two types of electric charges.

For further experiments, let’s replace the “measuring cups” with a more advanced device called an electrometer (Fig. 219).

rice. 219
  The instrument consists of a metal rod and a lightweight metal pointer that can rotate around horizontal axis. This device is housed in a metal case covered with glass covers. The angle of deflection of the needle can be measured using a scale. The arrow rod is fixed in the body using a plexiglass sleeve. The rod with the arrow plays the same role as the foil cups in previous experiments - when a charged body touches the rod, the charge will flow to the rod and to the arrow, which will lead to its deflection. Moreover, the direction of deflection of the arrow does not depend on the type of charge reported.
  For further experiments we will use two identical electroscopes. Let's charge one of them using, for example, a glass rod. Next, let's start connecting the electrometer rods using various materials. When connecting rods using wooden, uncharged glass, ebonite, plastic sticks; textile threads, no changes occur - one electrometer remains charged, the second uncharged. If you connect the rods using a metal wire, then both electrometers are charged. Moreover, the deflection of the needle of the initially charged electrometer will decrease (Fig. 220).

rice. 220
  From the results of this experiment two conclusions can be drawn: important conclusions: firstly, some materials (metals) can transmit electrical charge, others (glass, plastic, wood) cannot; secondly, the charge can change, be more or less. The same experiments can be repeated using the second type (“resin”) electricity. The results will be the same - materials that conduct “glass” electricity also conduct “resin” electricity. If the “glass” charge is redistributed between the electrometers, then the “resin” charge also behaves.
  So, we can divide materials into two groups - those that transmit electric charge (these materials are called conductors), and those that do not transmit electric charge (they are called insulators). By the way, the electrometer rod is separated from the body using an insulator bushing so that the electric charge does not “spread” over the body, but remains on the rod and pointer.
  Different deviations of the electrometer needle clearly indicate that the force of interaction between charged bodies can be different, and therefore the magnitude of the charges can be different. Consequently, the charge can be characterized by a certain numerical value (and not as we said earlier - “is it or is it not”).
  Another interesting result- if you touch the rod of a charged electrometer with your hand, the electrometer is discharged - the charge disappears. Even on the basis of these qualitative observations, it is possible to explain where the charge disappears when touched by a hand. The human body is a conductor, so charge can flow into the human body.
  To confirm this idea about the quantitative nature of the charge, the following experiment can be performed. Let's charge one electrometer - note the angle of deflection of the arrow. Let's connect it to a second electrometer - the angle of deflection of the needle will noticeably decrease. Let's remove the contact between the devices and the hand, discharge the second electrometer, after which we connect the electrometers again - the deviation of the needle will decrease again. Thus, the electric charge can be divided into parts. You can also conduct the opposite experiment - gradually adding a charge to the electrometer.
  Let’s “mix” now the two available types of electricity. To do this, we charge one electrometer with “glass” electricity, and the second with “resin” electricity, trying to ensure that the initial deviations of the needles of both electrometers are approximately the same.

rice. 221
  After this, we will connect the rods of the electrometers with metal wire (on an insulating handle so that the charges do not escape"). The result of this experiment may be surprising - both electroscopes were discharged, or the “glass” and “resin” electricity neutralized and compensated for each other.
  Therefore, it turns out to be possible to attribute various types charge different algebraic signs - one charge is called positive, the second negative. It is reasonable to assume that the strength of the interaction depends on the net charge. If the electrometers were initially charged different types electricity, but varying degrees(the deviations of the arrows are different), and then connect them, then only partial compensation of the charges will occur - the arrows will be deflected, but to a much lesser extent.
  Historically, the “glass” charge was called positive, and the “resin” charge became negative 3.
  The device we have described, an electrometer, allows us only to qualitatively judge the magnitude of charges and carry out quantitative measurements impossible. Try, for example, to bring your hand to a charged electrometer (without touching the rod) - the deflection of the needle will increase! Bring a charged stick to the uncharged rod without touching the rod - the arrow will deflect, although the electrometer is not charged. We will return to the explanation of these facts later.

Historical information about the electrification of bodies

Vera Borisovna Malgina, physics teacher, State Budgetary Educational Institution Education Center No. 80 Central region St. Petersburg

The history of the study of electricity is interesting and instructive. Some of the most significant historical examples can be used in lessons to increase interest in the topic.

Greek philosopher Thales of Miletus, who lived 624-547. BC, discovered that amber, rubbed on fur, acquires the property of attracting small items- fluff, straws, etc. For a number of centuries this property was attributed only to amber.

The birth of the doctrine of electricity is associated with the name of William Gilbert (1540-1603), physician to Queen Elizabeth of England. Gilbert published his first work on electricity in 1600, where he described the results of his 18 years of research and put forward the first theories of electricity and magnetism. Here, for the first time in the history of science, he used the term “electricity” (from Greek word"electron", which means "amber"). He was one of the first scientists to approve experience, experiment as the basis of research. He showed that friction electrifies not only amber, but also many other substances (diamond, sapphire, crystal, glass) and that they attract not only dust particles, but also metals, wood, leaves, pebbles, and even water and oil. Gilbert discovered the phenomenon of electricity leakage in a humid atmosphere, its destruction in a flame, the shielding effect on the electric charge of paper, fabric or metals, and the insulating properties of some materials.

The next stage in the development of the study of electricity was the experiments of the German scientist Otto von Guericke (1602-1686). In 1672 His book was published, which described experiments on electricity. Most interesting achievement Guericke was the inventor of the “electric machine”. The “electric machine” was a ball made of sulfur and mounted on an iron pole. Guericke rotated the ball and rubbed it with the palm of his hand. Subsequently, the scientist improved his “machine” several times. With the help of this “machine,” Guericke discovered that in addition to attraction, there is also electrical repulsion.

In 1729, the Englishman Stephen Gray (1666 - 1736) experimentally discovered the phenomenon of electrical conductivity. He established that electricity can be transmitted from one body to another through a metal wire. Electricity did not spread along the silk thread. In this regard, Gray divided all bodies into conductors and non-conductors of electricity.

Two types of electricity

More than 250 years have passed since the existence of two types of electricity became known. In 1733, the French physicist Charles Dufay (1698 - 1739) published in French and English magazines articles. In them he described the results of his experiments on electrification different bodies. To detect and primitively measure electricity, Du Fay used Gilbert's versor, making it much more sensitive.

From numerous and ingeniously performed experiments, Du Fay concluded that there are two types of electricity. Electricity alone arises when rubbing copal ( fossil resin), wax, silk and many other substances. Another appears when rubbing glass, rock crystal, precious stones, wool, etc. Therefore, Dufay called the first of them resin, and the second glass electricity. A body possessing any of the two types of electricity attracts light bodies to itself (it is this property that has been designated by the word “electricity” since ancient times). The difference is that bodies charged with the same electricity (glass or resin) repel each other, but if one body is charged with glass and the other with resin electricity, then they are mutually attracted.

Thus, fundamental facts were established: the presence of two types of electricity and the existence of electrical forces of attraction and repulsion. Naturally, the question arises about how this or that electricity appears in bodies. At that time, one could only speculate about this.

Franklin vibe. One such guess was made in 1750 American physicist(as well as well-known government and public figure, one of the leaders of the struggle of the American colonies for independence) Benjamin Franklin.

According to Franklin, each body contains a special electrical substance (fluid, as they said then), something like an electric liquid. The particles of this electric fluid repel each other, but are strongly attracted by the particles of the body, so that any body acts on the electric fluid like a sponge drawing water into itself (there are many particles of the electric fluid fewer particles the body itself, otherwise they could not penetrate into the body). But the presence of an electric fluid in a body does not make it electrified if it is contained in the body in some, so to speak, normal amount. When one body is rubbed by another, part of the electrical fluid flows from one body to the other, and then both bodies become electrified. The body into which the electric liquid has flowed and in which its excess is therefore created in comparison with the normal amount becomes the owner of glass electricity. The second body, in which the electrical fluid is less than the normal amount, is charged with resin electricity. However, Franklin gave these two types of electricity different names. Franklin called glass electricity (possessed by bodies with an excess of electrical fluid) positive, and resin electricity (possessed by bodies with a lack of electrical fluid) - negative. These names have survived to this day, as well as other terms introduced into the science of electricity by Franklin: charge, discharge, capacitor, battery, conductor, etc.

Electricity and... stockings.

Another explanation was proposed in 1759 by the Englishman R. Simmer. The reason for this was the rather interesting observations he made.

Simmer used to wear two pairs of stockings: black wool for warmth and white silk for beauty. Removing both stockings from his leg at once and pulling one out of the other, Simmer saw how both stockings inflated, reproduced the shape of the leg and were attracted to each other. However, stockings of the same color, both black and white, repel each other. If you hold two white stockings in one hand and two black stockings in the other, then when the hands come together, the mutual repulsion of stockings of the same color and the attraction of multi-colored ones leads to a funny fuss between them - stockings of opposite colors seem to pounce on each other and weave into one bizarre ball .

These observations led Simmer to the conclusion that in every body there is not one, but two electrical fluids - positive and negative, contained in the body in equal quantities. When rubbing two bodies, one of them can pass from one body to another, then in one body there will be an excess of one of the liquids, and in the other - its deficiency.

Electrical conflict .

This is how two ideas about electricity emerged. For a long time, almost a century and a half, none of them received universal recognition.

When at the end XVII-early In the 19th century, it became possible to obtain and study direct electric current, and a dispute arose about what exactly “flows” in a circuit containing a current source and conductors. There were doubts about whether the electricity that is obtained by rubbing bodies is the same as that which flows into electrical circuit. The latter even received special name- galvanic electricity. But still, many believed that two Simmer electricity flowed simultaneously in the conductors of an electrical circuit, and called electric current an electrical conflict, since these electricity flows in opposite directions. So, for example, when in 1820 H. Oersted published a brochure in which he described the action of current on the magnetic needle that he had discovered, he called it: “Experiments relating to the effect of electric conflict on the magnetic needle.”

Then the readers understood this strange name for us, and the brochure was a success due to the fundamental importance of the discovery made.

The old dispute between the two theories - Franklin and Simmer - was finally resolved only in late XIX- the beginning of the 20th century. Now we know that Simmer must be recognized as the winner in the dispute. "Simmer's electric liquids" are negatively charged electrons and positively charged protons, which in the same number contained in every neutral body, in every atom of matter.

But something turned out to be true in Franklin’s theory: when rubbing bodies, only one “fluid” can move from one body to another - negatively charged electrons. However, the body they transfer to becomes negatively charged, while Franklin considered it to be positively charged. This is due to the fact that Franklin considered it necessary to call Du Fay's glass electricity positive. From this choice made by Franklin it follows that we attribute to the electron negative sign charge, and the fact that the direction of electric current is taken to be the direction of movement of positive charges, although in the vast majority of conductors, primarily metal ones, negatively charged particles actually move. In electrolytes and gases, electric current is oncoming traffic both positive and negative particles. But now no one considers it an electrical conflict.

First theories of electricity

Along with the accelerated development of experimental research into electrical phenomena, theories of these phenomena also arise.

Of course, even before the middle of the 18th century. there were some considerations about the nature of electricity. But they were very primitive. In most cases electrical actions were explained by the presence of certain electrical atmospheres around charged bodies.

In the middle of the 18th century. More meaningful theories of electrical phenomena are appearing. These theories can be divided into two main groups:

First group are theories of electrical phenomena based on the principle long-range.

Second group- these are theories based on the principle closeactions.

Let us first dwell on the development of the theory of long-range action, which received in the 18th century. almost universal acceptance. The founders of the theory of long-range action were Franklin and the St. Petersburg academician Epinus.

Franklin back in the 40s of the 18th century. developed a theory of electrical phenomena. He suggested that there is a special electrical matter, which is a kind of thin, invisible liquid. Particles of this matter have the property of repelling from each other and being attracted to a particle of ordinary matter, i.e. particles of matter, according to modern concepts.

Aepinus assumes that electrical matter is present in bodies in certain quantities, and in that case its presence is not detected. But if an excess of this matter appears in the body, then the body becomes positively electrified; on the contrary, if there is a lack of this matter in the body, then the body will become negatively electrified. (The name “positive and negative electricity,” which remained in science, belongs to Franklin.)

Electrical matter, according to Franklin, consists of especially thin particles, so it can pass through matter. It passes especially easily through conductors. From Franklin's theory follows a very important point about the conservation of electric charge. Indeed, to create, for example, a negative charge on any body, you need to take away from it a certain amount of electrical fluid, which must move to another body and form there positive charge the same size. After connecting these bodies, electrical matter will again be distributed between them so that these bodies become electrically neutral.

Franklin demonstrated this point experimentally. Two people stand on a tar disk (to isolate them from surrounding objects and the ground). One person rubs a glass tube. Another touches this tube with his finger and extracts a spark. Both people now find themselves electrified: one with negative electricity, the other with positive electricity. But at the same time their charges are equal absolute value. After contact, people will lose their charges and become electrically neutral.

Franklin's theory was developed by Franz Aepinus (1724 - 1802). At the same time, Apinus seemed to take Newton's theory of gravitation as a model. Newton assumed that long-range forces act between all particles of ordinary bodies. These forces are central, i.e. they act in a straight line connecting the particles.

Aepinus assumes that central long-range forces also act between particles of electrical matter. Only gravitational forces are attractive forces, while the forces acting between particles of electrical matter are repulsive forces. In addition, between particles of electrical matter and particles of ordinary matter, just like Franklin, there are attractive forces. And these forces, similar to the forces of gravity, are long-range and central. Further, Apinus, like Newton, says that the forces he introduced must be recognized as a fact and that at present it is impossible to explain how they act through space. He does not want to come up with unfounded hypotheses. Here he completely copies Newton.

Aepinus goes further, comparing gravitational and electrical forces. He suggests that the forces acting between particles of electrical matter “vary inversely with the square of the distance. This can be assumed with some plausibility, because such a dependence is apparently supported by an analogy with other natural phenomena.” This supposed analogy makes it possible for Apinus to construct a theory of electrical phenomena. One of his interesting works was the study of electrical induction. Epinus showed that if a charged body is brought close to a conductor, then electric charges appear on the conductor. In this case, the side to which the charged body is brought is electrified by a charge of the opposite sign. And vice versa, on the remote part of the conductor a charge of the same sign is formed as on the brought body.

If you remove the charged body, the conductor again becomes uncharged. But if a conductor can be divided into two parts in the presence of a charged body, then the result will be two conductors charged with opposite charges, which will remain even when the inducing charge is removed.

Epinus also confirmed the law of conservation of electric charge. He wrote: “If I want to increase the amount of electrical matter in any body, I must inevitably take it outside it and, therefore, reduce it in some other body.”

Simultaneously with the theory of electrical phenomena, based on the concept of long-range action, theories of these phenomena appear, which are based on the principle of short-range action. Lomonosov can be considered one of the founders of this theory. Lomonosov was an opponent of the theory of long-range action. He believed that the body cannot act on others instantly through empty or filled space. He believed that electrical interaction is transmitted from body to body through a special medium that fills all empty space, in particular the space between the particles that make up “considerable matter,” i.e. substance. Electrical phenomena, according to Lomonosov, should be considered as certain microscopic movements occurring in the ether. The same applies to magnetic phenomena.

Another St. Petersburg academician, Euler, also supported the point of view of short-range action in the theory of electricity and magnetism. In the middle of the 18th century, like Lomonosov, he advocated the theory of short-range action. He assumed the existence of an ether, the movement and properties of which explained the observed electrical phenomena. However, the theoretical ideas of Lomonosov and Euler could not be developed at that time. Soon Coulomb's law was discovered. It was the same in form as the law universal gravity, and, naturally, his understanding was the same as the understanding of the law of gravity. Thus, Coulomb's law was taken as proof of the theory of long-range action.

After the discovery of Coulomb's law, the theory of long-range action completely replaces the theory of short-range action. And only in the 19th century. Michael Faraday revives the theory of short-range action. However, its general recognition begins in the second half of the 19th century, after experimental proof Maxwell's theories.

Literature

1. Great encyclopedia in sixty-two volumes. - M.: Terra, 2006

2. Gorev L. A. Entertaining experiments in physics. Book for teachers. - M.: Education, 1985

By hanging light balls of foil on two threads and touching each of them with a glass rod rubbed on silk, you can see that the balls will repel each other. If you then touch one ball with a glass rod rubbed on silk, and the other with an ebonite rod rubbed on fur, the balls will attract each other. This means that glass and ebonite rods, when rubbed, acquire charges of different signs , i.e. exist in nature two types of electric charges having opposite signs: positive and negative. We agreed to assume that a glass rod rubbed on silk acquires positive charge , and an ebonite stick, rubbed on fur, acquires negative charge .

From the described experiment it also follows that charged bodies interact with each other. This interaction of charges is called electrical. At the same time charges of the same name, those. charges of the same sign , repel each other, and unlike charges attract each other.

The device is based on the phenomenon of repulsion of similarly charged bodies electroscope- a device that allows you to determine whether a given body is charged, and electrometer, a device that allows you to estimate the value of electric charge.

If you touch the rod of an electroscope with a charged body, the leaves of the electroscope will disperse, since they will acquire a charge of the same sign. The same thing will happen to the needle of an electrometer if you touch its rod with a charged body. At the same time, than more charge, so on larger angle the arrow will deviate from the rod.

From simple experiments it follows that the force of interaction between charged bodies can be greater or less depending on the magnitude of the acquired charge. Thus, we can say that the electric charge, on the one hand, characterizes the body’s ability to electrical interaction, and on the other hand, is a quantity that determines the intensity of this interaction.

The charge is indicated by the letter q , taken as a unit of charge pendant: [q ] = 1 Cl.

If you touch one electrometer with a charged rod, and then connect this electrometer with a metal rod to another electrometer, then the charge on the first electrometer will be divided between the two electrometers. You can then connect the electrometer to several more electrometers, and the charge will be divided between them. Thus, the electric charge has property of divisibility . The charge divisibility limit, i.e. the smallest charge existing in nature is the charge electron. The electron charge is negative and equal to 1.6*10 -19 Cl. Any other charge is a multiple of the electron charge.

Modern life cannot be imagined without electricity; this type of energy is used most fully by humanity. However, not all adults are able to remember from school course physics definition of electric current (this is a directed flow of elementary particles, having a charge), very few people understand what it is.

What is electricity

The presence of electricity as a phenomenon is explained by one of the main properties of physical matter - the ability to have an electric charge. They can be positive and negative, while objects with oppositely polar signs are attracted to each other, and “equivalent” ones, on the contrary, repel. Moving particles are also the source of a magnetic field, which once again proves the connection between electricity and magnetism.

At the atomic level, the existence of electricity can be explained as follows. The molecules that make up all bodies contain atoms made up of nuclei and electrons circulating around them. These electrons can, under certain conditions, break away from the “mother” nuclei and move to other orbits. As a result, some atoms become “understaffed” with electrons, and some have an excess of them.

Since the nature of electrons is such that they flow to where there is a shortage of them, the constant movement of electrons from one substance to another constitutes electric current (from the word “to flow”). It is known that electricity flows from the minus pole to the plus pole. Therefore, a substance with a lack of electrons is considered to be positively charged, and with an excess - negatively, and it is called “ions”. If we're talking about about the contacts of electrical wires, then the positively charged one is called “zero”, and the negatively charged one is called “phase”.

In different substances, the distance between atoms is different. If they are very small, electron shells literally touch each other, so electrons easily and quickly move from one nucleus to another and back, which creates the movement of an electric current. Substances such as metals are called conductors.

In other substances, interatomic distances are relatively large, so they are dielectrics, i.e. do not conduct electricity. First of all, it's rubber.

Additional information. When the nuclei of a substance emit electrons and move, energy is generated that heats the conductor. This property of electricity is called “power” and is measured in watts. This energy can also be converted into light or another form.

For continuous flow of electricity through the network, the potentials are at end points conductors (from power lines to house wiring) must be different.

History of the discovery of electricity

What electricity is, where it comes from, and its other characteristics are fundamentally studied by the science of thermodynamics with related sciences: quantum thermodynamics and electronics.

To say that any scientist invented electric current would be wrong, because since ancient times many researchers and scientists have been studying it. The term “electricity” itself was introduced into use by the Greek mathematician Thales; this word means “amber”, since it was in experiments with an amber stick and wool that Thales was able to generate static electricity and describe this phenomenon.

The Roman Pliny also studied electrical properties resins, and Aristotle studied electric eels.

At a later time, the first person to thoroughly study the properties of electric current was V. Gilbert, physician to the Queen of England. The German burgomaster from Magdeburg O.f. Gericke is considered the creator of the first light bulb made from a grated sulfur ball. A the great Newton deduced proof of the existence of static electricity.

At the very beginning of the 18th century, the English physicist S. Gray divided substances into conductors and non-conductors, and the Dutch scientist Pieter van Musschenbroek invented a Leyden jar capable of accumulating an electric charge, i.e. it was the first capacitor. American scientist and politician B. Franklin for the first time in scientific terms developed the theory of electricity.

The entire 18th century was rich in discoveries in the field of electricity: the electrical nature of lightning was established, an artificial magnetic field was constructed, the existence of two types of charges (“plus” and “minus”) and, as a consequence, two poles was revealed (US naturalist R. Simmer) , Coulomb discovered the law of interaction between point electric charges.

In the next century, batteries were invented (by the Italian scientist Volta), an arc lamp (by the Englishman Davey), and also a prototype of the first dynamo. The year 1820 is considered the year of the birth of electrodynamic science, the Frenchman Ampere did this, for which his name was assigned to the unit for indicating the strength of electric current, and the Scotsman Maxwell developed light theory electromagnetism. Russian Lodygin invented an incandescent lamp with a coal core - the progenitor of modern light bulbs. Just over a hundred years ago the neon lamp was invented (French scientist Georges Claude).

To this day, research and discoveries in the field of electricity continue, for example, the theory quantum electrodynamics and interactions of weak electric waves. Among all the scientists involved in the study of electricity, special place belongs to Nikola Tesla - many of his inventions and theories about how electricity works are still not appreciated.

Natural electricity

For a long time it was believed that electricity “by itself” does not exist in nature. This misconception was dispelled by B. Franklin, who proved electrical nature lightning It was they, according to one version of scientists, that contributed to the synthesis of the first amino acids on Earth.

Electricity is also generated inside living organisms, which generates nerve impulses, providing motor, respiratory and other vital functions.

Interesting. Many scientists believe human body autonomous electrical system, which is endowed with self-regulation functions.

Representatives of the animal world also have their own electricity. For example, some breeds of fish (eels, lampreys, stingrays, anglerfish and others) use it for protection, hunting, obtaining food and orientation in underwater space. A special organ in the body of these fish generates electricity and stores it, like in a capacitor, its frequency is hundreds of hertz, and its voltage is 4-5 volts.

Getting and using electricity

Electricity is the basis these days comfortable life, therefore humanity needs its constant production. For these purposes, various types of power plants are being built (hydroelectric power plants, thermal, nuclear, wind, tidal and solar), capable of generating megawatts of electricity with the help of generators. This process is based on the transformation of mechanical (energy of falling water at a hydroelectric power station), thermal (combustion of carbon fuel - hard and brown coal, peat at thermal power plants) or interatomic energy ( atomic decay radioactive uranium and plutonium at nuclear power plants) into electrical power plants.

Much scientific research has been devoted to electrical forces The lands they all seek to exploit atmospheric electricity for the benefit of humanity - generating electricity.

Scientists have proposed many interesting current generator devices that make it possible to produce electricity from a magnet. They use abilities permanent magnets commit useful work in the form of torque. It arises as a result of repulsion between similarly charged magnetic fields on stator and rotor devices.

Electricity is more popular than all other energy sources because it has many advantages:

• easy movement to the consumer;
• quick conversion to thermal or mechanical view energy;
• new areas of its application are possible (electric vehicles);
• discovery of new properties (superconductivity).

Electricity is the movement of differently charged ions inside a conductor. This great gift from nature, which people have known since ancient times, and this process is not yet completed, although humanity has already learned to extract it in huge quantities. Electricity plays a huge role in the development of modern society. We can say that without it, the lives of most of our contemporaries will simply stop, because it’s not for nothing that when the electricity goes out, people say that they “turned off the lights.”

Video

The path to electricity began in ancient times. Even the Greek Thales from Miletus, who lived in the 6th–5th centuries. BC, the property of amber, when rubbed, was known to attract light objects - feathers, straw, hair, and even create sparks. Until the sixteenth century, this was the only way to electrify bodies, which had no practical application.

In the Middle Ages, when the compass, which made it possible to determine the course of a ship, became known to the West, the study of magnetic phenomena acquired practical significance. In 1600, the book of the English scientist Gilbert (1544–1603) “On the Magnet, magnetic bodies and the big magnet - the Earth." In it the author has already described known properties magnet, as well as his own discoveries. He proved that it is possible to electrify not only amber, but also diamond, rock crystal and a number of other minerals. Unlike a magnet, which can only attract iron (other magnetic materials they didn’t know at that time), an electrified body attracts many bodies. He called all bodies that have the property of attracting electricians, introducing this term into use for the first time (in Greek, amber is electron). At the same time, he identified substances that were not capable of being electrified.
Following Hilbert important place in the history of the science of electricity belongs to the German burgomaster Otho von Guericke (1602–1686). His research in the field of electricity laid the foundation for experimental electrostatics. He designed the first device for generating static electricity - a sulfur ball with a diameter of 15–20 cm, rotating on an axis. Having placed the ball on the axis, he observed various electrical phenomena. The fluff attracted to the ball, pushing off from it, hovered in the air, being attracted to other bodies, especially pointed ones, and then again to the ball. At the same time, he discovered the phenomenon of mutual repulsion of two electrified bodies. The experimenter showed that electrostatic charges can spread along a half-meter linen thread, attracting light objects to its end. Rubbing the ball with his hand in the dark, he discovered a faint glow. In this case, the role of one of the poles was played by the inventor himself.

Later, Guericke's machine was improved by other inventors. The sulfur ball was replaced by a glass one, and leather pads were used as one of the poles instead of the researcher’s palms. In 1729, the Englishman Gray discovered the phenomenon of electrical conductivity. He established that electricity can be transmitted from one body to another through a metal wire. Electricity did not spread along the silk thread. In this regard, Gray divided all bodies into conductors and non-conductors of electricity. The French scientist Dufay discovered that there are two types of electricity. One type of electricity is generated by rubbing glass, rock crystal, wool and some other bodies. Du Fay called this electricity glass electricity. The second type of electricity is generated by rubbing amber, silk, paper and other substances. Du Fay called this type of electricity resin. The scientist found that bodies electrified by one type of electricity repel, and by different types they attract. German physicist Ewald Jürgen von Kleist and Dutch physicist Pieter van Musschenbroek created the first capacitor, the Leyden jar, in 1745. The dielectric in it was the walls of a glass jar, which is where the name came from. It was a glass vessel filled with water, wrapped in foil. A metal rod passed through a stopper was immersed in water. They believed that the accumulation of electrical charges was facilitated by the water in the jar.

The American scientist Benjamin Franklin (1706–1790) proved that water does not play any role in the accumulation of electrical charges; dielectric glass has this property. In the forties of the 18th century, he put forward the theory that there is only one kind of electricity - a special electrical matter consisting of tiny particles capable of penetrating into matter. If a body has an excess of electrical matter, it is charged positively; if there is a deficiency, the body is negatively charged. Franklin proposed to call Du Fay's glass electricity positive, and resin electricity - negative, and introduced into practice the signs "plus" and "minus", as well as the terms capacitor, conductor, charge.

Already by end of the XVIII century properties and behavior stationary charges have been sufficiently studied and to some extent explained. However, nothing was known about electric current– moving charges, since there was no device (detector) that could register the movement of charges. The currents received from the electrostatic machine were too small to be measured. At the end of the 19th century. physician Galvani (Luigi Aiosio Galvani) discovered the first detector design, not artificial, but natural - biological. While dissecting frogs, he discovered the appearance in the tissues of the dissected frog of short-term pulses of electric current, which contributed to a sharp contraction of its muscles. Comparing his results with previous studies, he concluded about the existence of “animal” electricity. In the theory he proposed, a model was used to describe the behavior of the muscle electric capacitor. It was assumed that outer surface and the inside of the frog muscle are the plates of the capacitor. Charging of such a capacitor occurs due to the excitation of the spinal cord, which is transmitted through the nerve. At the moment the plates of the “living” capacitor are closed by a metal hook, a discharge occurs, and an electric current begins to flow in the circuit, as a result of which muscle twitching occurs. In this case, the discharge does not depend on whether the circuit is closed with a conductor made of a homogeneous metal or from two different metals. Galvani later suggested that “animal” electricity, unlike conventional electricity, “operates more efficiently through dissimilar conductors.” However, professor from the University of Pavia Alessandro Guiseppe Antonio Anastasio Volta, having carefully repeated all of Galvani’s experiments, did not agree with the author’s conclusions. Volta argued that the phenomenon discovered by Galvani was purely physical, not physiological, and animal electricity did not exist. The reason for the contraction of the frog's leg, according to Volta, who invented the direct current source (voltaic column), lies in the nature of dissimilar metals completing the circuit. Alexandro Volta, like Luigi Galvani, firmly adhered to what he created until the end of his days. scientific theories, despite the fact that some of them were incorrect. Thus, he believed that the basis of the action of the current source he invented was the contact potential difference. However, after a long time it was found that the cause of the occurrence of electromotive force in a galvanic cell is chemical reaction metals with a conductive liquid – electrolyte. Complete theory The galvanic cell was created only at the end of the 19th century. Research of the 20th century showed that the phenomenon of contact potential difference significantly affects the performance characteristics of various radio-electronic devices and must be taken into account when developing them. Contact difference potentials has a noticeable effect on the type of current-voltage characteristics of vacuum lamps. The operation of semiconductor electronics elements is based on the contact potential difference: p-n junctions and metal-semiconductor contacts.

Thus, the 19th century became the century of theoretical understanding of the nature of magnetism and electricity. It was in this century that the existence of electromagnetic waves, which predetermined the technical revolution in the field of communications, and then telecommunications technologies.