What is the electric current? First recall, what is the definition of current we have learned?

Quite simply, the directional movement of charged particles in a conductor is an electric current.

Only when a substance has charged particles that can move freely, it can transmit electric current—that is, conduct electricity. These charged particles that participate in conduction are called carriers. For metals, for example, only the outer electrons of atoms can act as carriers.

“Motsin shugabanci” a cikin ma’anar lantarki sau da yawa ana kuskuren fahimta. Mutane da yawa suna tunanin yana nufin motsi tare da wata hanya, ba shakka ba! Shin alkiblar motsi na electrons a cikin kewayen AC baya canzawa?

In fact, orienteering is relative to “random movement”!

Since electrons are microscopic particles, they must be in thermal motion all the time. Thermal motion is a random motion, as shown in the figure below.

This movement is actually very fast. For example, in metals at room temperature, the speed of electronic thermal movement is on the order of hundreds of kilometers per second!

Idan ka dubi wannan motsi na bazuwar, za ka ga cewa alkiblar motsin kowane barbashi ba ta dace ba a kowane lokaci. Idan aka haɗa ma’aunin saurin waɗannan barbashi, sakamakon kusan sifili ne.

Yanzu ƙara filin lantarki zuwa madubin, kuma electron yana ɗaukan motsi na shugabanci bisa ga motsi bazuwar. A zaton cewa filin lantarki yana hagu na wani ɗan lokaci, motsi na electrons yana kama da haka. Jajayen ƙwallayen suna wakiltar atom ɗin ƙarfe akan lattice ɗin crystal, kuma ɗigon motsi masu sauri suna wakiltar electrons kyauta.

Does it look fast? That’s because electronic movement is really fast! But in fact, the random motion, which accounts for a large proportion of it, does not contribute to the current. When the random motion is eliminated, the rest is just like the slow look below.

Indeed, the directional movement of electrons is much slower than the speed of thermal movement. This “grinding” movement of electrons is called drift, or “drift”. Sometimes, electrons will run in the opposite direction because of collisions with atoms. But in general, electrons move in one direction.

Idan filin lantarki ya canza alkibla, alkiblar drift electron shima zai canza.

Don haka, wannan nau’in motsi na al’ada yana nufin cewa jimlar saurin duk electrons da ke shiga cikin gudanarwa a wani lokaci ba sifili ba ne, amma gabaɗaya yana cikin wata hanya. Ana iya canza wannan shugabanci a kowane lokaci, kuma wannan shine yanayin alternating current.

Saboda haka, halin yanzu ba shine “motsin shugabanci” na cajin lantarki ba kamar yadda “motsi na gama gari” na cajin lantarki.

Girman halin yanzu a cikin jagora yana bayyana ta ƙarfin halin yanzu. An ayyana ƙarfin halin yanzu a matsayin adadin wutar lantarki da ke wucewa ta ɓangaren madugu a cikin lokaci ɗaya, wato.

Mun koyi wasu adadi na zahiri waɗanda ke ɗauke da kalmar “ƙarfi”, kamar ƙarfin filin lantarki da ƙarfin shigar da maganadisu. Gabaɗaya suna wakiltar rabon kowane lokaci naúrar, yanki naúrar (ko ƙarar naúrar, ƙaƙƙarfan kusurwa naúrar). Koyaya, kalmar “ƙarfi” a cikin ƙarfin halin yanzu baya nuna rabon yanki na yanzu.

In fact, another physical quantity is responsible for the distribution of current to area, which is current density.

Tunda ma’anar wutar lantarki shine motsin jagora na cajin lantarki, dole ne a sami wata alaƙa tsakanin ƙarfin halin yanzu da saurin ɗigo!

Domin samun wannan alaƙa, dole ne mu fara fayyace ra’ayi mai ɗaukar hankali, wato, adadin masu ɗauka a cikin juzu’in naúrar, wanda aka bayyana ta .

Ana ɗauka cewa sashin ƙetaren madugu shine, maida hankali mai ɗaukar kaya shine, saurin ɗigo, kuma cajin da aka caje shine.

Then the charge in the conductor on the left side of the surface is, and these charges will pass through the surface within a certain period of time, so

Wannan ƙayyadaddun magana ce ta ƙarfin halin yanzu.

A halin yanzu yawa shi ne rabo daga halin yanzu zuwa yanki, don haka girman da yawa na yanzu shine, amma an ayyana shi a matsayin vector, kuma alkiblar ita ce alkiblar maɗaukakiyar motsin motsi na ma’auni mai inganci, don haka drift na electrons a cikin injin lantarki. Ana iya samun karfe daga wannan Gudun, a matsayin misali a kasa.

Yi la’akari da waya ta jan karfe, ɗauka cewa kowane atom ɗin jan ƙarfe yana ba da gudummawar lantarki a matsayin mai ɗaukar hoto. Akwai mol 1 na jan karfe, ƙarar sa shine, molar mass shine, yawa shine, sannan mai ɗaukar nauyin wayar tagulla shine.

Where is Avogadro’s constant. The density of copper is found, and the value obtained by substituting is about unit/cubic meter.

Idan aka ɗauka cewa radius na wayar jan ƙarfe shine 0.8mm, mai gudana a halin yanzu shine 15A, = 1.6 C, kuma ana ƙididdige saurin gudu na electrons kamar haka.

Ana iya ganin cewa, haƙiƙanin ɗigon gudu na electrons ɗin ƙanƙane ne.

For those who study circuits, the above is the complete definition of current.

But in physics, the above definition of current is actually only a narrow definition. More general currents are not limited to conductors, as long as the movement of electric charges is current. For example, when the electrons of a hydrogen atom move around the nucleus, an electric current is formed in its orbit.

Suppose the amount of electronic charge is and the period of movement is. Then every time that elapses, there is such a large amount of charge passing through any cross section of the loop, so the current intensity is based on the relationship between period, frequency and angular velocity, and the current can also be expressed as

For another example, a charged metal disk, rotating around its axis, also forms loop currents with different radii.

Irin wannan halin yanzu ba halin yanzu ba ne na yau da kullun kuma ba zai iya haifar da zafin Joule ba! Ba za a iya samar da ainihin kewaye ba.

In ba haka ba, za ku ba ni lissafin yawan zafin joule da ake samarwa a cikin daƙiƙa guda ta hanyar electrons na hydrogen atom?

In fact, the current in vacuum does not satisfy Ohm’s law. Because, for the electric current formed by the movement of charged particles in the vacuum, the carriers are not collided similar to the lattice in the metal, so the vacuum has no resistance and no conductance.

Motsin cajin wutar lantarki yana haifar da wutar lantarki, kuma cajin wutar lantarki da kanta yana burge filin lantarki. Wannan yana da sauƙi don haifar da rashin fahimta. Don haka mutane da yawa suna tunanin cewa dole ne a fallasa filin lantarki na barbashi da aka caje waɗanda ke samar da wutar lantarki. Amma a zahiri, don tafiyar da halin yanzu a cikin janareta na yau da kullun, masu ɗaukar hoto suna gudana akan bango wanda ya ƙunshi adadi mai yawa na ion ƙarfe masu inganci, kuma jagoran da kansa ba shi da tsaka tsaki!

Sau da yawa muna kiran irin wannan nau’in halin yanzu na musamman “daidai na halin yanzu”. Daidai a nan yana nufin cewa yana samar da filin maganadisu a daidai wannan yanayin da na yau da kullun na yau da kullun!

Tunatarwa: Kar a rikita “daidai na halin yanzu” anan tare da “madaidaicin da’ira” a cikin binciken da’ira

A haƙiƙa, lokacin da muka fara nazarin filin maganadisu, wutar lantarki da ke cikin dokar Biot-Saffar ita ce wutar lantarki ta gama gari wacce ke ɗauke da wannan daidaitaccen wutar lantarki. Tabbas, tafiyar da halin yanzu a cikin ma’auni na Maxwell shima yana nuni ne ga gamammiyar halin yanzu.

Those who have studied the photoelectric effect know that when the photoelectron drifts from the cathode to the anode, if the influence of air is ignored, this current is caused by the movement of electric charges in the vacuum, and there is no resistance, so it is not restricted by Ohm’s law.

Don haka, shin wannan shine kawai abin da ake nufi da wutar lantarki a kimiyyar lissafi?

No! There are also two types, namely magnetizing current and displacement current.

Hakanan magudanan ruwa iri biyu ne, waɗanda, kamar yadda sunan yake nunawa, ana kuma gabatar da su don bayyana maganadisu. A wasu kalmomi, sun rabu da ainihin halayen “motsi na caji” na yanzu!

Abin mamaki! Babu motsin cajin lantarki, to me yasa za’a iya kiransa da wutar lantarki?

Kar ku damu, kuma ku saurare ni a hankali.

Bari mu fara duba halin yanzu magnetizing.

An gano cewa maganadisu yana faruwa ne ta hanyar motsin wutar lantarki (ba la’akari da bayanin maganadisu ta hanyar abubuwan da ke cikin spine na yanzu ba). Domin yin bayani game da maganadisu na halitta, masanin kimiyyar lissafi na Faransa Ampere ya gabatar da hasashen “zazzagewar kwayoyin halitta”.

Kamar yadda aka nuna a hoton da ke ƙasa, ana iya ɗaukar kowane zarra ko ƙwayoyin cuta a matsayin suna da cajin wutar lantarki da ke juyawa a tsakiya, suna samar da ɗan ƙaramin madauri, wato, “zazzagewar kwayoyin halitta”.

According to the law that the electric current excites the magnetic field, this molecular circulation will produce a physical quantity called magnetic moment. Its size is the area enclosed by the molecular circulation multiplied by the equivalent current of the molecular circulation, and its direction is in a right-handed spiral relationship with the direction of the circulation, namely

Babu shakka, alkiblar lokacin maganadisu daidai yake tare da jagorar filin maganadisu da aka kirkira ta hanyar zazzagewar halin yanzu.

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A karkashin yanayi na al’ada, tsarin tsarin kwayoyin halitta na wani abu yana da rikici, don haka abu ba shine magnetic ba, kamar yadda aka nuna a gefen hagu na hoton da ke ƙasa. Lokacin da aka yi wa filin maganadisu na waje, waɗannan zazzagewar kwayoyin halitta za a kusan tsara su da kyau. Kamar yadda aka nuna a gefen dama na hoton da ke ƙasa, lokacin maganadisu ana jera su ta hanya ɗaya gwargwadon iyawa, kamar ƙananan alluran maganadisu marasa adadi waɗanda aka taru don samar da filin maganadisu gabaɗaya, kuma duk abin da ya ƙunshi su ya zama magnetic.

A ce akwai maganadisu na silindarical, zagayawa na ƙwayoyin cuta na ciki an tsara su da kyau, kuma sassan kowane nau’in zagayawa na kwayoyin halitta a gefen sashin maganadisu an haɗa su tare don samar da babban kewayawa, kamar yadda aka nuna a cikin hoton da ke ƙasa.

Dangane da wannan, zamu iya tunanin cewa maganadisu na mashaya kamar solenoid ne mai kuzari. A wasu kalmomi, akwai wani abin da ba a iya gani a halin yanzu da ke matse shi a saman magnet ɗin! Ba za a iya haɗa irin wannan halin yanzu da amfani da shi ba. Yana da iyaka ga saman maganadisu. Muna kiransa “binding current” ko “magnetizing current”.

Saboda haka, magnetizing halin yanzu na yanzu ne, saboda daidai yake da na yanzu da aka samu ta hanyar motsi na cajin lantarki na ainihi, wanda zai iya haifar da filin maganadisu!

Let’s look at the displacement current again.

Dangane da ka’idar madauki na Ampere, abin da ke tattare da ƙarfin filin maganadisu akan rufaffiyar hanya daidai yake da jujjuyawar yawa na yanzu akan kowace ƙasa mai lanƙwasa da wannan tafarki ke daure, wato, ana kiran wannan ka’idar Stokes’ theorem a lissafi. Yana gaya mana cewa abin da ke cikin vector a kowane rufaffiyar hanya dole ne ya zama daidai da jujjuyawar murɗawarsa (a nan) zuwa duk wani saman da ke daure da rufaffiyar hanya.

Since it is a mathematical theorem, it must always be correct, because mathematics is a logical system based on axioms.

Therefore, the Ampere Loop Theorem must always hold!

However, the talented Scottish physicist Maxwell discovered that when faced with an unstable current circuit, the Ampere loop theorem was contradictory.

The typical unstable current occurs during the charging and discharging of the capacitor. As shown in the figure below, there is an unstable current during the short period of capacitor charging.

But the circuit is disconnected between the capacitor plates, which will cause a serious problem.

Suppose we consider a closed path that bypasses the wire, as shown in the figure below, the circle marked by C, and the curved surface with it as the boundary can be arbitrarily selected. In the figure, the circular plane enclosed by C itself and across the capacitor are selected. The curved surface of the left plate.

Dangane da madauwari madauwari, ana iya ganin cewa bisa ga lanƙwasa, amma a matsayin madauki mai mahimmanci na ƙarfin filin maganadisu, ya kamata a ƙayyade ƙimarsa!

Yadda za a yi?

Maxwell ya yi imanin cewa dole ne a kafa ka’idar madauki na Ampere. Yanzu da aka sami matsala, dole ne ya kasance saboda wani yanki na halin yanzu ba mu gano shi a baya ba, amma akwai!

So, how to find out this part of the current?

Tunda matsalar tana tsakanin faranti, fara daga tsakanin faranti.

Ta hanyar bincike, Maxwell ya gano cewa ba tare da la’akari da caji ko fitarwa ba, akwai adadi na zahiri tsakanin faranti na capacitor a kowane lokaci wanda ke aiki tare da girma da shugabanci na yanzu. Shi ne tushen lokaci na jujjuyawar motsin motsi na lantarki, wato, an ayyana shi azaman ƙaura.

Idan aka yi la’akari da cewa wannan bangare shi ne bangaren da ba a taba gano shi a da ba, to, a halin yanzu cikakkiya. Wato, ko da yake kewayawa tsakanin faranti an katse, abin da ya samo asali na motsin motsi na lantarki da jimlar halin yanzu tare, gaba ɗaya , Tabbatar da ci gaba da halin yanzu a kowane lokaci.

Komawa ga sabani na baya, yanzu mun san cewa, bisa ga buƙatun ka’idar Stokes, lokacin da ake ƙididdige juzu’i na yawa na yanzu don rufaffiyar farfajiya, yawan ƙaura na yanzu yakamata kuma a yi la’akari da shi, wato, cikakkiyar madauki na ampere. Theorem saboda haka, Ta hanyar “gano” wannan sabon bangaren na yanzu, an warware rikicin Ampere Loop Theorem!

Dalilin da ya sa ba a amfani da “gabatarwa” a nan, amma “gano” ana amfani da shi a nan. Abin da nake so in jaddada shi ne, irin wannan nau’in ruwa ba diyya ba ne na lissafi, amma abu ne na gaske, amma ba a gano shi a baya ba.

Me yasa ta wanzu tun farko? Domin yana aiki a matsayin wutar lantarki, kamar conduction current, yana zuga wutar maganadisu daidai gwargwado, sai dai babu motsi na cajin lantarki, ba a buƙatar waya, kuma ba za a iya samar da zafin Joule ba, don haka an yi watsi da shi!

Amma a zahiri yana wanzuwa da kanta, kawai kiyaye ƙarancin bayanan martaba, yana jin daɗin filin maganadisu koyaushe!

In other words, when we face a magnetic field, the original definition of current is too narrow. The essence of electric current is not the movement of electric charge, it should be something that can excite a magnetic field.

So far, the several forms of current have been introduced. They all exist objectively, and what they have in common is that all currents can equally excite the magnetic field.