Kirchhoff’s current law is the first among the two of Kirchhoff’s laws and is also refereed as Kirchhoff ‘s point law or Kirchhoff’s First law.

Kirchhoff ‘s Current Law States That:

The total algebraic sum of all the currents entering and leaving a node in an electrical network is zero.

and mathematically:

Kirchhoff’s current law is based on and is derived from the conversation of charge which states that: “Charge can neither be created nor be destroyed” , so if charge can neither be created nor be destroyed then, all the charges entering a node must leave the node which concludes the result that “The total algebraic sum of all the currents entering and leaving a node in an electrical network is zero”.

For Example:

In the following node of an electrical network:

kirchhoff’s current law

The currents I1 , I2 and I4 are flowing into the node N through the branches A , B and D respectively and the currents I3, I5 are flowing outwards from the node N through the branches C and E respectively.

Applying the Kirchhoff’s law in the node N:

or,

Thus, 

Kirchhoff’s Current law is one of the fundamental laws of electronics and is very useful in analyzing and solving the circuits and DC Networks ( Also AC Networks) which cannot be solved by using the ohm’s law. KCL is the base while analyzing and designing any kind of circuit and electronic device.

Limitations of Kirchhoff’s Current Law:

Kirchhoff’s Current Law is based on the fact that all the currents or charge entering a node in a electrical network must leave the node.

But in real life situation, specially while considering AC source this is not exactly true. In many cases a very small of charge is leaked or conserved through the nodes and conductors due to parasitic capacitance and inductance, Due to which the Kirchhoff’s Current Law is not exactly true in many cases. But the leakage or conserved charge is very minimal in amount in most cases and specially while considering DC source ; So the limitation of KCL due to leakage and conserved charges can be neglected in most cases.

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