{"id":145178,"date":"2024-03-21T14:06:09","date_gmt":"2024-03-21T14:06:09","guid":{"rendered":"https:\/\/www.electricity-magnetism.org\/lei-de-ampere-entenda-e-calcule\/"},"modified":"2024-03-22T05:55:29","modified_gmt":"2024-03-22T05:55:29","slug":"lei-de-ampere-entenda-e-calcule","status":"publish","type":"post","link":"https:\/\/www.electricity-magnetism.org\/pt-br\/lei-de-ampere-entenda-e-calcule\/","title":{"rendered":"Lei de Amp\u00e8re | Entenda e Calcule"},"content":{"rendered":"

Entenda a Lei de Amp\u00e8re e como ela relaciona corrente el\u00e9trica e campo magn\u00e9tico, sua formula\u00e7\u00e3o matem\u00e1tica e aplica\u00e7\u00f5es pr\u00e1ticas na f\u00edsica e engenharia.<\/p>\n

O que \u00e9 a Lei de Amp\u00e8re<\/h2>\n

\nA Lei de Amp\u00e8re, nomeada em homenagem ao f\u00edsico franc\u00eas Andr\u00e9-Marie Amp\u00e8re, \u00e9 um dos pilares fundamentais do eletromagnetismo. Esta lei explica como um campo magn\u00e9tico \u00e9 gerado a partir de uma corrente el\u00e9trica. Em termos simples, a Lei de Amp\u00e8re afirma que a circula\u00e7\u00e3o do campo magn\u00e9tico ao longo de um caminho fechado \u00e9 diretamente proporcional \u00e0 corrente el\u00e9trica total que atravessa qualquer superf\u00edcie com esse caminho como borda.\n<\/p>\n

Formula\u00e7\u00e3o Matem\u00e1tica<\/h2>\n

\nA express\u00e3o matem\u00e1tica da Lei de Amp\u00e8re \u00e9 dada pela equa\u00e7\u00e3o de Amp\u00e8re-Maxwell, que \u00e9 uma das quatro equa\u00e7\u00f5es de Maxwell. A forma integral da lei pode ser escrita como:\n<\/p>\n

\\[ \\oint_{\\partial S} \\vec{B} \\cdot d\\vec{l} = \\mu_0 I_{\\text{enc}} \\]<\/p>\n

\nNessa equa\u00e7\u00e3o, \\(\\vec{B}\\) representa o campo magn\u00e9tico, \\(d\\vec{l}\\) \u00e9 um elemento diferencial de comprimento ao longo do caminho fechado (contorno da superf\u00edcie \\(S\\)), \\(\\mu_0\\) \u00e9 a permeabilidade magn\u00e9tica do v\u00e1cuo, e \\(I_{\\text{enc}}\\) \u00e9 a corrente l\u00edquida que passa atrav\u00e9s da superf\u00edcie \\(S\\). O s\u00edmbolo de integral circular indica que a integra\u00e7\u00e3o \u00e9 feita ao longo de um caminho fechado.\n<\/p>\n

Aplica\u00e7\u00f5es da Lei de Amp\u00e8re<\/h2>\n

\nA Lei de Amp\u00e8re tem diversas aplica\u00e7\u00f5es na f\u00edsica e na engenharia. Ela \u00e9 fundamental no c\u00e1lculo de campos magn\u00e9ticos em configura\u00e7\u00f5es de corrente muito sim\u00e9tricas, como em fios retos longos, solenoides e toroides. Al\u00e9m disso, \u00e9 utilizada no projeto de motores el\u00e9tricos, transformadores e outros dispositivos eletromagn\u00e9ticos. Em eletr\u00f4nica, \u00e9 importante para entender a indut\u00e2ncia e o comportamento dos circuitos quando submetidos a correntes vari\u00e1veis.\n<\/p>\n

Como Calcular com a Lei de Amp\u00e8re<\/h2>\n

\nPara aplicar a Lei de Amp\u00e8re e calcular o campo magn\u00e9tico, voc\u00ea precisa seguir alguns passos:\n<\/p>\n

    \n
  1. Identificar a simetria do problema para escolher um caminho fechado (\\( \\partial S \\)) onde o campo magn\u00e9tico \u00e9 constante ou pode ser facilmente integrado.<\/li>\n
  2. Calcular a corrente total \\( I_{\\text{enc}} \\) que passa atrav\u00e9s da superf\u00edcie \\(S\\) cujo contorno \u00e9 o caminho escolhido.<\/li>\n
  3. Resolver a integral ao longo do caminho para encontrar a circula\u00e7\u00e3o do campo magn\u00e9tico.<\/li>\n
  4. Usando a simetria do problema, encontrar a express\u00e3o do campo magn\u00e9tico \\( \\vec{B} \\) em fun\u00e7\u00e3o da dist\u00e2ncia ao fio ou outra fonte de corrente.<\/li>\n<\/ol>\n

    \nVamos considerar um exemplo comum: um fio longo e reto conduzindo uma corrente \\(I\\). Usando a Lei de Amp\u00e8re, podemos escolher um caminho circular com raio \\(r\\) centrado no fio, pois o campo magn\u00e9tico \u00e9 o mesmo em qualquer ponto do caminho. A integral torna-se simplesmente \\(B \\cdot 2\\pi r\\), que \u00e9 igual a \\(\\mu_0 I\\) segundo a Lei de Amp\u00e8re. Assim, o campo magn\u00e9tico a uma dist\u00e2ncia \\(r\\) do fio \u00e9 dado por:\n<\/p>\n

    \\[ B = \\frac{\\mu_0 I}{2\\pi r} \\]<\/p>\n

    Conclus\u00e3o<\/h2>\n

    \nA Lei de Amp\u00e8re \u00e9 uma ferramenta poderosa na an\u00e1lise de campos magn\u00e9ticos gerados por correntes el\u00e9tricas. Ao compreender e aplicar esta lei, \u00e9 poss\u00edvel n\u00e3o s\u00f3 explanar fen\u00f4menos naturais como tamb\u00e9m projetar uma gama de dispositivos eletromagn\u00e9ticos. A beleza da f\u00edsica se revela quando leis como a de Amp\u00e8re mostram a interconectividade entre eletricidade e magnetismo, abrindo portas para inova\u00e7\u00f5es tecnol\u00f3gicas e um melhor entendimento do mundo ao nosso redor.<\/p>\n","protected":false},"excerpt":{"rendered":"

    Entenda a Lei de Amp\u00e8re e como ela relaciona corrente el\u00e9trica e campo magn\u00e9tico, sua formula\u00e7\u00e3o matem\u00e1tica e aplica\u00e7\u00f5es pr\u00e1ticas na f\u00edsica e engenharia.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_generate-full-width-content":"","footnotes":""},"categories":[84],"tags":[85],"class_list":["post-145178","post","type-post","status-publish","format-standard","hentry","category-ecuaciones","tag-ecuaciones","generate-columns","tablet-grid-50","mobile-grid-100","grid-parent","grid-50"],"yoast_head":"\nLei de Amp\u00e8re | Entenda e Calcule<\/title>\n<meta name=\"description\" content=\"Entenda a Lei de Amp\u00e8re e como ela relaciona corrente el\u00e9trica e campo magn\u00e9tico, sua formula\u00e7\u00e3o matem\u00e1tica e aplica\u00e7\u00f5es pr\u00e1ticas na f\u00edsica e engenharia.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.electricity-magnetism.org\/pt-br\/lei-de-ampere-entenda-e-calcule\/\" \/>\n<meta property=\"og:locale\" content=\"pt_BR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Lei de Amp\u00e8re | Entenda e Calcule\" \/>\n<meta property=\"og:description\" content=\"Entenda a Lei de Amp\u00e8re e como ela relaciona corrente el\u00e9trica e campo magn\u00e9tico, sua formula\u00e7\u00e3o matem\u00e1tica e aplica\u00e7\u00f5es pr\u00e1ticas na f\u00edsica e engenharia.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.electricity-magnetism.org\/pt-br\/lei-de-ampere-entenda-e-calcule\/\" \/>\n<meta property=\"og:site_name\" content=\"Electricity - 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