Kirchhof’s Current law:
It states that, “The algebraic sum of all the currents entering into the loop and leaving the loop must be equal to zero.”
Derivation of KCl
Using the equation of continuity,
▽.J + ∂९/∂t = 0
▽.J = -∂९/∂t
∫▽.J dv = -∫∂९/∂t dv
∮ J.ds = - ∂/∂t ∫९ dv
i = -∂/∂t Q
I.e. ΣI=0