How to Calculate Kirchhoff's Current Law (KCL)

A short tutorial on Kirchhoff's current law(KCL) to determine the current in the electric circuit with the simple example.

Electric Circuit Analysis

Current Kirchhoffs Law or Kirchhoffs Current Law is also referred as Kirchhoffs first law, Kirchhoffs point rule, or Kirchhoffs junction rule. KCL explains about the conversation of charge entering and leaving a junction. To put it in detail, it states that "the charge entering the node is exactly equal to the current leaving the node as its only option is to leave the node, as no charge can be lost within the node. The sum of current entering and leaving a junction is equal to Zero. The first law of Kirchhoffs is also known as Conservation of Charge. Learn here how to calculate Kirchhoffs current law (KCL).
How To Calculate Kirchhoffs Current Law
In an electric circuit analysis, the current in the circuit can be expressed as follows.
Kirchhoffs Current Law Formula:
I(exiting) + I(entering) = 0
Kirchchoffs Current Law Formula New
The above image is an example of Kirchhoffs first law. Two positive currents I1,I2, are entering the node three positive currents are leaving the node, I3, I4 and I5.

Kirchhoffs Current Law Example:
Step 1:
Lets consider a simple single junction as an example. The amps of the current I1,I2 entering the node is 6 amps and 5 amps respectively. The amps of the current I3, I4 and I5 leaving the node is 4 amps, 5 amps and 2 amps.
I1 - 6 amps
I2 - 5 amps
I3 - 4 amps
I4 - 5 amps
- 2 amps
Kirchhoffs Current Law Example
Step 2: Here we have the formula
I1 + I2 = I3 + I4 + I5
Substituting the values in the formula.
6 + 5 = 4 + 5 + 2
11 = 11 amps
Kirchhoff Current Law Result
Here as per Kirchhoff law, the total current entering the node is equal to the total current leaving the node. The example holds true for the Kirchhoffs current law.

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