Kirchhoff's current law

 Kirchhoff’s first law “the sum of the currents flowing through a junction is an electric circuit is zero.”

KCL

in this figure consider the node O we can see that i1, i3, i4 current are entering in this node and i2, and i5 exit from this node.if we take the sign of currents flowing towards O as  positive , then current flowing away from point o will be assigned negative sign.from this law in mathematically

(i1)+ (i3) + (i4)-(i2)-(i5) =0

Or, (i1) + (i3) + (i4) = (i2) + (i5)

That means incoming current and outgoing current of a node is zero.

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