Electric current

Klassik elektrodinamika
Olim Uilyam Gilbert o'zining "De Magnete" (1600) asarida elektr va magnetizm jismlarni tortish va itarish qobiliyatiga ega bo'lsa-da, bir-biridan farq qiluvchi ta'sirlar ekanligini taklif qildi. Dengizchilar chaqmoq chaqishi kompas ignasini buzish qobiliyatiga ega ekanligini payqashgan, ammo chaqmoq va elektr o'rtasidagi bog'liqlik 1752 yilda Benjamin Franklin tomonidan taklif qilingan tajribalargacha tasdiqlanmagan. Magnitizm Romagnosi edi, u 1802 yilda voltaik qoziq bo'ylab simni ulash yaqin atrofdagi kompas ignasini burishganini payqadi. Biroq, ta'sir 1820 yilgacha, Orsted shunga o'xshash tajribani o'tkazgunga qadar ma'lum bo'lmadi. Orstedning ishi Amperga elektromagnetizm nazariyasini yaratishga ta'sir qildi, bu mavzuni matematik asosga qo'ydi.
Klassik elektromagnetizm deb nomlanuvchi elektromagnetizmning aniq nazariyasi XIX asr davomida turli fiziklar tomonidan ishlab chiqilgan bo'lib, u oldingi ishlanmalarni yagona nazariyaga birlashtirgan va yorug'likning elektromagnit tabiatini kashf etgan Jeyms Klerk Maksvellning ishida yakuniga etgan. Klassik elektromagnetizmda elektromagnit maydon Maksvell tenglamalari deb ataladigan tenglamalar to'plamiga bo'ysunadi va elektromagnit kuch Lorents kuch qonuni bilan berilgan.

One of the peculiarities of classical electromagnetism is that it is difficult to reconcile with classical mechanics, but it is compatible with special relativity.

According to Maxwell's equations, the speed of light in a vacuum is a universal constant, dependent only on the electrical permittivity and magnetic permeability of free space. This violates Galilean invariance, a long-standing cornerstone of classical mechanics. One way to reconcile the two theories is to assume the existence of a luminiferous aether through which the light propagates. However, subsequent experimental efforts failed to detect the presence of the aether. After important contributions of Hendrik Lorentz and Henri Poincaré, in 1905, Albert Einstein solved the problem with the introduction of special relativity, which replaces classical kinematics with a new theory of kinematics that is compatible with classical electromagnetism.
In addition, relativity theory shows that in moving frames of reference a magnetic field transforms to a field with a nonzero electric component and vice versa; thus firmly showing that they are two sides of the same coin, and thus the term "electromagnetism." (For more information, see Classical electromagnetism and special relativity.)

Klassik elektromagnetizmning o'ziga xos xususiyatlaridan biri shundaki, klassik mexanika bilan kelishish qiyin, lekin u maxsus nisbiylik bilan mos keladi.
Maksvell tenglamalariga ko'ra, vakuumdagi yorug'lik tezligi universal konstanta bo'lib, faqat bo'sh joyning elektr o'tkazuvchanligi va magnit o'tkazuvchanligiga bog'liq. Bu klassik mexanikaning uzoq vaqtdan beri davom etayotgan poydevori bo'lgan Galiley o'zgarmasligini buzadi. Ikki nazariyani uyg'unlashtirishning bir usuli - yorug'lik tarqaladigan nurli efir mavjudligini taxmin qilishdir. Biroq, keyingi eksperimental harakatlar efir mavjudligini aniqlay olmadi. Hendrik Lorentz va Genri Puankarening muhim hissalaridan so'ng, 1905 yilda Albert Eynshteyn klassik kinematikani klassik elektromagnetizmga mos keladigan kinematikaning yangi nazariyasi bilan almashtiradigan maxsus nisbiylik nazariyasini joriy etish bilan bog'liq muammoni hal qildi.
Bundan tashqari, nisbiylik nazariyasi ko'rsatadiki, harakatlanuvchi sanoq sistemalarida magnit maydon nolga teng bo'lmagan elektr komponentli maydonga aylanadi va aksincha; Shunday qilib, ular bir tanganing ikki tomoni ekanligini qat'iy ko'rsatib turibdi va shuning uchun "elektromagnitizm" atamasi. (Qo'shimcha ma'lumot uchun Klassik elektromagnetizm va maxsus nisbiylik nazariyasiga qarang.)