Kirchhoff’s Current Law

By Nirmal -
Kirchhoff’s Current Law states that the algebraic sum of currents at a node is zero
a ‘node’ is the technical term for a junction in a circuit, where two or more branches are joined
together.
b) the phrase ‘algebraic sum’ reminds us that we have to take account of the current direction, as well asmagnitude, when applying Kirchhoff’s Current Law.
This Law is used in circuit analysis to define relationships between
currents flowing in branches of the circuit. To apply Kirchhoff’s Current Law rigorously, we must first make an
arbitrary choice of positive current direction. Suppose currents flowing in
to the node (I1, I2) are treated as positive contributions to the algebraic
sum (and conversely currents flowing from the node are treated as negative contributions), then the algebraic
sIt must be emphasised that the choice of sign convention when using Kirchhoff’s Current Law is entirely
arbitrary and, of course, makes no difference to the result obtained. However, it is good practice to be
consistent in your choice, because this minimises the chance of making a mistake when writing down the
algebraic sum.

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