Describing electromagnetic interaction.

Quantization of electric charge

Any experimentally observed electric charge is always a multiple of one elementary- this assumption was made by B. Franklin in 1752 and subsequently was repeatedly tested experimentally. The elementary charge was first measured experimentally by Millikan in 1910.

The fact that electric charge occurs in nature only in the form of an integer number of elementary charges can be called quantization of electric charge. At the same time, in classical electrodynamics the question of the reasons for charge quantization is not discussed, since charge is an external parameter and not a dynamic variable. A satisfactory explanation of why the charge must be quantized has not yet been found, but a number of interesting observations have already been obtained.

Fractional electric charge

Repeated searches for long-lived free objects with fractional electric charge, carried out using various methods over a long period of time, did not yield results.

It is worth noting, however, that the electric charge of quasiparticles may also not be a multiple of the whole. In particular, it is quasiparticles with a fractional electric charge that are responsible for the fractional quantum Hall effect.

Experimental determination of elementary electric charge

Avogadro's number and Faraday's constant

Josephson effect and von Klitzing constant

Another precise method of measuring elementary charge is to calculate it from the observation of two effects of quantum mechanics: the Josephson effect, which produces voltage fluctuations in a particular superconducting structure, and the quantum Hall effect, the effect of quantizing the Hall resistance or conductivity of a two-dimensional electron gas in strong magnetic fields and at low temperatures . Josephson constant

Where h- Planck's constant, can be measured directly using the Josephson effect.

can be measured directly using the quantum Hall effect.

From these two constants the magnitude of the elementary charge can be calculated:

see also

Notes

1. Elementary charge (English). The NIST Reference on Constants, Units, and Uncertainty. . Retrieved May 20, 2016.
2. The value in SGSE units is given as a result of recalculating the CODATA value in coulombs, taking into account the fact that a coulomb is exactly equal to 2,997,924,580 units of electric charge SGSE (

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1 elementary electric charge [e] = 1.60217733000001E-20 charge unit SGSM

Initial value

Converted value

coulomb megacoulomb kilocoulomb milliculon microcoulomb nanocoulomb picoculon abcoulomb unit of charge SGSM statcoulon SGSE-unit of charge franklin ampere-hour ampere-minute ampere-second faraday (unit of charge) elementary electric charge

More about electric charge

General information

Surprisingly, we encounter static electricity every day - when we pet our beloved cat, comb our hair, or pull on a synthetic sweater. So we ourselves inevitably become generators of static electricity. We literally bathe in it, because we live in the strong electrostatic field of the Earth. This field arises due to the fact that it is surrounded by the ionosphere, the upper layer of the atmosphere - an electrically conductive layer. The ionosphere was formed under the influence of cosmic radiation and has its own charge. While doing everyday things like heating food, we don’t think at all about the fact that we are using static electricity when we turn on the gas supply valve on a burner with automatic ignition or bring an electric lighter to it.

Examples of static electricity

Since childhood, we have been instinctively afraid of thunder, although in itself it is absolutely safe - just an acoustic consequence of a menacing lightning strike, which is caused by atmospheric static electricity. Sailors from the times of the sailing fleet fell into awe when they observed the lights of St. Elmo on their masts, which are also a manifestation of atmospheric static electricity. People endowed the supreme gods of ancient religions with an integral attribute in the form of lightning, be it the Greek Zeus, the Roman Jupiter, the Scandinavian Thor or the Russian Perun.

Centuries have passed since people first began to be interested in electricity, and sometimes we do not even suspect that scientists, having drawn thoughtful conclusions from the study of static electricity, are saving us from the horrors of fires and explosions. We've tamed electrostatics by pointing lightning rods at the sky and equipping fuel tankers with grounding devices that allow electrostatic charges to escape safely into the ground. And, nevertheless, static electricity continues to misbehave, interfering with the reception of radio signals - after all, up to 2000 thunderstorms are raging on Earth at the same time, which generate up to 50 lightning strikes every second.

People have been studying static electricity since time immemorial; We even owe the term “electron” to the ancient Greeks, although they meant something slightly different by this - that’s what they called amber, which was perfectly electrified by friction (other - Greek ἤλεκτρον - amber). Unfortunately, the science of static electricity was not without casualties - Russian scientist Georg Wilhelm Richmann was killed by a lightning bolt during an experiment, which is the most dangerous manifestation of atmospheric static electricity.

Static electricity and weather

To a first approximation, the mechanism of formation of charges in a thundercloud is in many ways similar to the mechanism of electrification of a comb - electrification by friction occurs in the same way. Ice floes, formed from small droplets of water, cooled due to transport by rising air currents to the upper, colder part of the cloud, collide with each other. Larger pieces of ice are charged negatively, and smaller pieces are charged positively. Due to the difference in weight, a redistribution of ice floes in the cloud occurs: large, heavier floes fall to the lower part of the cloud, and smaller, lighter floes gather at the top of the thundercloud. Although the cloud as a whole remains neutral, the lower part of the cloud receives a negative charge, and the upper part receives a positive charge.

Just as an electrified comb attracts a balloon by inducing an opposite charge on the side closest to the comb, a thundercloud induces a positive charge on the surface of the Earth. As a thundercloud develops, the charges increase, while the field strength between them increases, and when the field strength exceeds a critical value for the given weather conditions, an electrical breakdown of the air occurs - a lightning discharge.

Humanity is indebted to Benjamin Franklin - later President of the Supreme Executive Council of Pennsylvania and the first Postmaster General of the United States - for the invention of the lightning rod (it would be more accurate to call it a lightning rod), which forever saved the world's population from fires caused by lightning striking buildings. By the way, Franklin did not patent his invention, making it available to all mankind.

Lightning did not always cause only destruction - the Ural ore miners determined the location of iron and copper ores precisely by the frequency of lightning strikes at certain points in the area.

Among the scientists who devoted their time to studying the phenomena of electrostatics, it is necessary to mention the Englishman Michael Faraday, later one of the founders of electrodynamics, and the Dutchman Pieter van Muschenbrouck, the inventor of the prototype of the electric capacitor - the famous Leyden jar.

Watching DTM, IndyCar or Formula 1 races, we don’t even suspect that mechanics call pilots to change tires to rain tires, relying on weather radar data. And these data, in turn, are based precisely on the electrical characteristics of approaching thunderclouds.

Static electricity is our friend and enemy at the same time: radio engineers do not like it, pulling grounding bracelets when repairing burnt circuit boards as a result of a nearby lightning strike - in this case, as a rule, the input stages of the equipment fail. If grounding equipment is faulty, it can cause severe man-made disasters with tragic consequences - fires and explosions of entire factories.

Static electricity in medicine

However, it comes to the aid of people with heart rhythm disturbances caused by chaotic convulsive contractions of the patient’s heart. Its normal operation is restored by passing a small electrostatic discharge using a device called a defibrillator. The scene of a patient returning from the dead with the help of a defibrillator is a kind of classic for a certain genre of cinema. It should be noted that movies traditionally show a monitor with a missing heartbeat signal and an ominous straight line, when in fact using a defibrillator does not help if the patient's heart has stopped.

Other examples

It would be useful to remember the need to metallize aircraft to protect against static electricity, that is, to connect all metal parts of the aircraft, including the engine, into one electrically integral structure. Static dischargers are installed at the tips of the entire tail of the aircraft to drain static electricity that accumulates during flight due to air friction against the aircraft body. These measures are necessary to protect against interference caused by static electricity and to ensure reliable operation of the avionics equipment.

Electrostatics plays a certain role in introducing students to the section “Electricity” - perhaps no other section of physics knows more spectacular experiments - here you have hair standing on end, and a balloon chasing a comb, and the mysterious glow of fluorescent lamps without any connection wires! But this glow effect of gas-filled devices saves the lives of electricians dealing with high voltage in modern power lines and distribution networks.

And most importantly, scientists have come to the conclusion that we probably owe the appearance of life on Earth to static electricity, or more precisely to its discharges in the form of lightning. During experiments in the middle of the last century, with the passage of electrical discharges through a mixture of gases, close in composition to the primary composition of the Earth’s atmosphere, one of the amino acids was obtained, which is the “building block” of our life.

To tame electrostatics, it is very important to know the potential difference or electrical voltage, for the measurement of which instruments called voltmeters were invented. The concept of electrical voltage was introduced by the 19th century Italian scientist Alessandro Volta, after whom this unit is named. At one time, galvanometers named after Volta's compatriot Luigi Galvani were used to measure electrostatic voltage. Unfortunately, these electrodynamic type devices introduced distortions into the measurements.

Study of static electricity

Scientists began systematically studying the nature of electrostatics since the work of the 18th century French scientist Charles Augustin de Coulomb. In particular, he introduced the concept of electric charge and discovered the law of interaction of charges. The unit of measurement of the amount of electricity - the coulomb (C) - is named after him. True, for the sake of historical justice, it should be noted that years earlier the English scientist Lord Henry Cavendish was engaged in this; Unfortunately, he wrote on the table and his works were published by his heirs only 100 years later.

The work of predecessors on the laws of electrical interactions enabled physicists George Green, Carl Friedrich Gauss and Simeon Denis Poisson to create a mathematically elegant theory that we still use today. The main principle in electrostatics is the postulate of the electron - an elementary particle that is part of any atom and is easily separated from it under the influence of external forces. In addition, there are postulates about the repulsion of like charges and the attraction of unlike charges.

Electricity measurement

One of the first measuring instruments was the simplest electroscope, invented by the English priest and physicist Abraham Bennett - two sheets of gold electrically conductive foil placed in a glass container. Since then, measuring instruments have evolved significantly - and they can now measure differences in the nanocoulomb units. Using particularly precise physical instruments, Russian scientist Abram Ioffe and American physicist Robert Andrews Millikan were able to measure the electric charge of an electron

Nowadays, with the development of digital technologies, ultra-sensitive and high-precision instruments with unique characteristics have appeared, which, due to their high input impedance, introduce almost no distortion into measurements. In addition to measuring voltage, such devices allow you to measure other important characteristics of electrical circuits, such as ohmic resistance and flowing current over a wide measurement range. The most advanced devices, called multimeters or, in professional jargon, testers because of their versatility, also allow you to measure the frequency of alternating current, the capacitance of capacitors and test transistors and even measure temperature.

Describing electromagnetic interaction.

Encyclopedic YouTube

• 1 / 5

  Any experimentally observed electric charge is always a multiple of 1 elementary- this assumption was made by B. Franklin in 1752 and subsequently was repeatedly tested experimentally. The elementary charge was first measured experimentally by Millikan in 1910.

  The fact that electric charge occurs in nature only in the form of an integer number of elementary charges can be called quantization of electric charge. At the same time, in classical electrodynamics the question of the reasons for charge quantization is not discussed, since charge is an external parameter and not a dynamic variable. A satisfactory explanation of why the charge must be quantized has not yet been found, but a number of interesting observations have already been obtained.

  Fractional electric charge

  Repeated searches for long-lived free objects with fractional electric charge, carried out using various methods over a long period of time, did not yield results.

  It is worth noting, however, that the electric charge of quasiparticles may also not be a multiple of the whole. In particular, it is quasiparticles with a fractional electric charge that are responsible for the fractional quantum Hall effect.

  Experimental determination of elementary electric charge

  Using Avogadro's number and Faraday's constant

  Through the Josephson effect and von Klitzing constant

  Another precise method of measuring elementary charge is to calculate it from the observation of two effects of quantum mechanics: the Josephson effect, which produces voltage fluctuations in a particular superconducting structure, and the quantum Hall effect, the effect of quantizing the Hall resistance or conductivity of a two-dimensional electron gas in strong magnetic fields and at low temperatures. . Josephson's constant

  K J = 2 e h (\displaystyle K_(\mathrm (J) )=(\frac (2e)(h)))(Where h Planck's constant)

  Josephson effect.

  R K = h e 2 , (\displaystyle R_(\mathrm (K) )=(\frac (h)(e^(2))),)

  can be measured directly using the quantum Hall effect.

  From these two constants the magnitude of the elementary charge can be calculated:

  e = 2 R K K J . (\displaystyle e=(\frac (2)(R_(\mathrm (K) )K_(\mathrm (J) ))).).

  Elementary electric charge, e, is the smallest electric charge known in nature. In quantum mechanics, an elementary charge is considered as a minimal portion (quantum) of an electric charge. Magnitude e elementary electric charge was established by direct measurements of R. Millikan in 1909-1911. and A.F. Ioffe in 1911-1913.

  Modern meaning of e: e= ≈ 1.6021892 ± 0.0000046 ×10 -19 C in the SI system (and 4.803242±0.000014×10 -10 SGSE units in the SGS system). The elementary electric charge is closely related to, which describes electromagnetic interaction.

  Quantization of electric charge

  Each experimentally observed electric charge is constantly a multiple of the elementary one. This assumption was made by B. Franklin in 1752 and was repeatedly tested experimentally. The elementary charge was calculated in 1834 by M. Faraday.

  Since electric charge occurs in nature only in the form of an integer number of elementary charges, we can talk about quantization of electric charge. In classical electrodynamics, the question of the reasons for charge quantization is not discussed, because charge is an external parameter, not a dynamic variable. There is no generally accepted explanation for why the charge must be quantized, although there are some conclusions:

  • If there is a magnetic monopole in nature, then according to quantum mechanics, its magnetic charge must be in a certain ratio with the charge any chosen elementary particle. It automatically follows from this that the mere existence of a magnetic monopole entails charge quantization. The only thing that needs to be done is to discover a magnetic monopole in nature.
  • In modern particle physics, there is a search for a model like , in which all known fundamental particles would turn out to be simple combinations of new, even more fundamental particles. In this case, the quantization of the charge of the observed particles would be a consequence of the properties of these fundamental particles.
  • It is also possible that all parameters of the observed particles will be described within the framework of a unified field theory, approaches to which are currently being developed. In such a theory, the magnitude of the electric charge of particles should be calculated from a small number of fundamental parameters, possibly related to the structure of space-time at ultrashort distances. If such a theory is constructed, then what we observe as an elementary electric charge will turn out to be some discrete invariant of space-time. However, specific generally accepted results in this direction have not yet been obtained.
  • The constancy of the electron charge is associated with the origin of electrons during the beta decay of neutrons, when protons and electrons with the same electrical charge are simultaneously produced. In this case, the value of the electron charge follows from the quantized properties of the neutron and is determined by the laws of beta decay.

  Fractional electric charge

  With the discovery, it became clear that elementary particles can have a fractional electric charge, for example, 1/3 and 2/3 of the value of the elementary charge. However, particles like quarks exist only in bound states (confinement). Thus, all known free particles have an electric charge that is a multiple of the elementary one, although in some experiments scattering by particles with the appearance of a fractional charge was observed.

  Repeated searches for free objects with a fractional electric charge, carried out using various methods over a long period of time, did not yield any results.

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  What does "elementary electric charge" mean?

  Encyclopedic Dictionary, 1998

  elementary electric charge

  ELEMENTARY ELECTRIC CHARGE (e) the minimum electric charge, positive or negative, the value of which is e ~ 4.8 10-10 SGSE units, or 1.6 10-19 C. Almost all charged elementary particles have a charge e or -e (with the exception of some resonances with a charge that is a multiple of e); particles with fractional electric charges have not been observed, however, in the modern theory of strong interaction - quantum chromodynamics, the existence of particles with charges that are multiples of 1/3 e (quarks) is assumed.

  Elementary electric charge

  e, the smallest electric charge known in nature. On the existence of E. e. h. It was first pointed out with certainty in 1874 by the English scientist J. Stoney. His hypothesis followed from the laws of electrolysis established by M. Faraday (1833≈34) (see Faraday's laws). In 1881, Stoney first calculated the magnitude of the electric current. charge of a monovalent ion equal to e = F/NA, where F ≈ Faraday number, NA ≈ Avogadro number. In 1911, the value of E. e. h. was established by direct measurements of R. Millikan. Modern meaning of e:

  e = (4.803242╠0.000014) 10-10 units. SGSE = (1.6021892 ╠ 0.0000046) 10-19k.

  The value of E. e. h. is a constant of electromagnetic interactions and is included in all equations of microscopic electrodynamics. E. e. h. exactly equal to the magnitude of the electric charge of the electron, proton and almost all other charged elementary particles, which are thus the material carriers of the smallest charge in nature. E. e. h. cannot be destroyed; this fact constitutes the content of the law of conservation of electric charge at the microscopic level. There is positive and negative E. e. h., and the elementary particle and its antiparticle have charges of opposite signs. The electric charge of any microsystem and macroscopic bodies is always equal to an integer multiple of the value e (or zero). The reason for this “quantization” of the charge has not been established. One of the hypotheses is based on the existence of Dirac monopoles (see Magnetic monopole). Since the 60s The hypothesis about the existence of particles with fractional electric charges ≈ quarks is widely discussed (see Elementary particles).