In this topic, you study Kirchhoff’s Current Law (KCL) – Statement, Explanation & Examples.
It states that in any electrical circuit, the algebraic sum of all branch currents that meet at a point (or junction) is always zero. Mathematically, it can be expressed as At a junction, EI = O
Here, the Greek letter sigma (Y) represents the algebraic sum of all similar terms. An algebraic sum is one in which the sign of the quantity is taken into account.
Explanation
Consider the simple case of four current carrying conductors meeting at a junction point O as illustrated in Fig. 2.16.
Fig. 2.16: Circuit to illustrate Kirchhoff’s first law
If we assume a current flowing towards the junction as positive and the other flowing away from it as negative, then according to the above law, we have
It means that
Thus, the sum of all currents leaving a junction is always equal to the sum of all the currents entering the junction.
This gives the alternative statement for the law. This is obvious because there cannot be any accumulation of electricity at the junction.