Nodes, Kirchhoff’s Current Law and Closed Loops

Nodes

A node is a place where two or more elements are connected.

Kirchhoff’s Current Law

The algebraic (signed) sum of all the currents at any node in a circuit equals to zero. Simply put, the charge does not build up at a node.

Closed Loops

A closed loop is defined in this way:

Starting at an arbitrarily selected node, trace a closed path in a circuit and return to the original node without passing through any intermediate node more than once. The loops, a, b, c, and d are partial of the closed loops in the circuit.

Therefore, a mesh is a closed loop that does not include any other closed loops. The loops a, b, and c are all meshes.