Electrical Circuits

Nodes, Branches & Loops

Node

- A point or junction where two or more circuit’s elements (resistor, capacitor, inductor etc) meet is called Nodes

Finding Nodes in Electric Circuits

After redrawing the above circuit, it becomes as below circuit, now you can easily find the total number of Nodes as shown in fig below:

Branch

That part or section of circuit which locate between two junctions is called branch

In branch, one or more elements can be connected and they have two terminals.

Finding Branches in Electric Circuits:

Loop

A closed path in circuit where more than two meshes can be occurred is called loop i.e. there may be many meshes in a loop, but a mesh does not contain on one loop.

Finding Loops in Electric Circuits:

Kirchhoff's circuit laws(KCL)

- are two equalities that deal with the current and potential difference (commonly known as voltage) in the lumped element model of electrical circuits. They were first described in 1845 by Gustav Kirchhoff. This generalized the work of Georg Ohm and preceded the work of Maxwell. Widely used in electrical engineering, they are also called Kirchhoff's rules or simply Kirchhoff's laws.

The current entering any junction is equal to the current leaving that junction. i₂ + i₃ = i₁ + i₄

Formulas:

Recalling that current is a signed (positive or negative) quantity reflecting direction towards or away from a node, this principle can be stated as:

current entering = current leaving

$\sum_{k=1}^n {I}_k = 0$

Kirchhoff's voltage laws(KVL)

- KVL is a fundamental law, as fundamental as Conservation of Energy in mechanics, for example, because KVL is really conservation of electrical energy. KVL and KCL are the starting point for analysis of any circuit. KCL and KVL always hold and are usually the most useful piece of information you will have about a circuit after the circuit itself.