The algebraic sum of all the currents entering any node is zero The algebraic sum of all the currents leaving a node is zero, or the algebraic sum of all the currents entering a node must equal the algebraic sum of all the currents leaving the node. i1+2-i2-i4=0 i1-2+2+i4=0 1+l2=3+4 The three equivalent equationsThe algebraic sum of all the currents leaving a node is zero, or the algebraic sum of all the currents entering a node must equal the algebraic sum of all the currents leaving the node. 0 1 2 3 4 i + i − i − i = 0 1 2 3 4 − i − i + i + i = 1 2 3 4 i + i = i + i The three equivalent equations The algebraic sum of all the currents entering any node is zero. 1 i 2 i 3 i 4 i