Name: kirchhoff's current law at circuit nodes
Uploaded: 2024-04-11T12:48:28.000Z
Duration: 1 min 4 s
Channel: JoVE

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Arizona Science Standards

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Physical Science

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HS+Phy.P4U1.8

Kirchhoff's Current Law

A lei atual de Kirchhoff, ou KCL, é baseada na lei da conservação de cargas. Ele afirma que a corrente total que entra e sai de um nó em um circuito é igual.
As correntes que saem do nó têm um sinal de menos, enquanto as correntes que entram no nó têm um sinal de mais.
Ao somar algebricamente as correntes em um nó e integrar ambos os lados em relação ao tempo, a carga total no nó é determinada.
De acordo com a conservação de carga, a carga elétrica líquida em qualquer nó permanece constante, garantindo que o nó não armazene carga líquida. Portanto, se a carga líquida for zero, a corrente total também será zero, validando o KCL.
A KCL pode ser generalizada para um limite fechado tratando um nó como uma superfície fechada condensada em um ponto.
Considere um painel solar que consiste em fontes de corrente paralelas. O KCL pode ser usado neste caso para encontrar a corrente combinada de fontes de corrente paralelas, somando algebricamente as correntes individuais em um nó.

lei atual de kirchhoff

No domínio da engenharia elétrica, o físico Gustav Robert Kirchhoff deu uma contribuição significativa em 1847 ao introduzir as leis de Kirchhoff para análise de circuitos elétricos. Essas leis, particularmente a Lei Atual de Kirchhoff (KCL), tornaram-se princípios fundamentais na compreensão e análise de circuitos elétricos.

A Lei Atual de Kirchhoff é baseada no princípio da conservação de carga. Afirma que em qualquer nó (um ponto onde dois ou mais elementos de circuito se encontram) em um circuito elétrico, a corrente total que entra no nó é igual à corrente total que sai do nó. Isto significa que nenhuma corrente é perdida na junção, refletindo o princípio fundamental de que a carga elétrica é conservada.

Na aplicação do KCL, as correntes que saem do nó recebem um sinal negativo, enquanto as correntes que entram no nó recebem um sinal positivo. Somando algebricamente essas correntes em um nó e integrando-as ao longo do tempo, pode-se determinar a carga elétrica total no nó.

De acordo com a lei da conservação de carga, a carga elétrica líquida em qualquer nó permanece constante ao longo do tempo, garantindo que o nó não armazene nenhuma carga líquida. Portanto, se a carga líquida em um nó for zero, a corrente total que entra e sai desse nó também deve ser zero. Isso valida a aplicação do KCL na análise de circuitos.

Curiosamente, KCL também pode ser generalizado para uma fronteira fechada, conceituando um nó como uma superfície fechada condensada em um ponto. Isso permite a aplicação de KCL em ambientes de circuitos mais complexos.

KCL também é útil na determinação da corrente combinada de fontes de corrente paralelas. Ao somar algebricamente as correntes individuais em um nó, a corrente total através desse nó pode ser encontrada.

Contudo, para que KCL seja verdadeiro, uma condição crítica deve ser atendida: um circuito não pode ter duas correntes desiguais em série. Isto porque, numa ligação em série, a mesma corrente flui através de todos os componentes, e qualquer discrepância violaria a lei da conservação de carga.

Lei Atual de Kirchhoff

A lei atual de Kirchhoff, ou KCL, é baseada na lei da conservação de cargas. Ele afirma que a corrente total que entra e sai de um nó em um circuito ...

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kirchhoff's current law at circuit nodes

Kirchhoff's Current Law explains how current behaves at a circuit node. A node is the point where two or more circuit elements meet. The law says the current entering a node equals the current leaving it. That balance follows the rule of charge conservation, which means electric charge is not lost at the junction.

When applying KCL, currents entering the node are treated as positive and currents leaving the node are treated as negative. The currents can be added algebraically at the node, and their sum can be integrated over time to find the total electric charge there. Because the net charge at a node stays constant over time, the node stores no net charge. If the net charge is zero, then the total current in and out of the node must also be zero.

KCL can also be extended to a closed boundary. In that case, a node is imagined as a closed surface compressed to a point. This makes the law useful in more complex circuit situations. It is also helpful for finding the combined current from parallel current sources, since the individual currents at a node are summed algebraically.

For KCL to remain valid, a circuit cannot have two unequal currents in series. In a series path, the same current must flow through each component. Any difference would break charge conservation. That is why KCL is a basic check when analyzing electrical circuits.

Kirchhoff's Current Law at Circuit Nodes

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kirchhoff's current law

Kirchhoff's Current Law explains how current behaves at a circuit node. A node is the point where two or more circuit elements meet. The law says the current entering a node equals the current leaving it. That balance follows the rule of charge conservation, which means electric charge is not lost at the junction. When applying KCL, currents entering the node are treated as positive and currents leaving the node are treated as negative. The currents can be added algebraically at the node, and...

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Learn how Kirchhoff's Current Law applies at circuit nodes, why entering and leaving current must balance, and how charge conservation supports circuit analysis.

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Kirchhoff's Current Law at Circuit Nodes

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