Any arrangement of the various electrical energy sources along with the different circuit elements is called an electrical network.

So as you see in the figure that there is an electrical energy source that is battery of 5 volt is connected with different circuit elements like switch, resistor, inductor and a dielectric capacitor as shown in the figure. This is an example of network.

## Network Element

Any individual circuit element with two terminals which can be connected to other circuit element, is called a network element.

## Branch

A part of the network which connects the various points of the network with one another is called a branch. It is represented by a single element it may be resistor, capacitor, battery, or other electrical element. The number of unique combination that can be obtained from n branches is 2^{n-1}.

In the figure there are five branch which is AB, BC, BD, CD and AD. As you see each one have single element.

## Junction Point

A point where three or more branches meet is called a junction point.

In this figure we have five branches that is AB, BC, BD, CD and AD. At least three of them should be connected to each other than that point will be junction. In this figure AB, BC and BD three branches connect at a single point that is B. So, B is junction in the circuit. Similarly o

## Mesh(or Loop)

Mesh is a set of branches forming a closed path in a network in such a way that if one branch is removed then remaining branches do not form a closed path. In the figure below we have three such loop or mesh are formed that is A-B-D, B-C-D and A-B-C-D.

## Node

A point at which two or more elements are joined together is called node. In this figure we have five branches that is AB, BC, BD, CD and AD. At least two of them should be connected to each other than that point will be node. So, in this figure there are four node that is A, B, C and D.

**NOTE :** Node can be junction but Junction cannot be a node.

**Linear Network**

**Classification of Electrical Networks**

A circuit or network whose parameters like resistance, inductance and capacitance are always constant irrespective of the change in time, voltage, temperature etc. is know as linear network. Ohm's law can be applied to such network. The mathematical equations of such network can be obtained by using the law of superposition.If value of resistance, inductance and capacitance will always constant.

**Non-linear Network**

A circuit whose parameters(resistance, inductance and capacitance) changes their values with change in time, temperature, voltage etc. is known as nonlinear network. The Ohm's law may be applied to such network.Such network does not follow the law of superposition.

If the values of resistance, inductance and capacitance changes.

**Bilateral Network**

A circuit whose characteristics, behavior is same irrespective of the direction of current through various elements is called bilateral network. Network consisting only resistances is example of bilateral network. In this figure if we apply some voltage at A and C terminal then we get some voltage at B and D terminal and vice versa of it is also possible. It means we input some voltage and take output at other end and vice versa of it is also possible. In both way output voltage will be same.

**Unilateral Network**

A circuit whose operation, behavior is dependent on the direction of the current through various elements is called unilateral network. Circuit consisting diodes, which allows flow of current only in one direction is good example of unilateral circuit. In the same network consisting of resistor only by adding diode we can make network unilateral network. As we know that diode have property to pass current in only one direction. So, In this type of network we can only take output and give output to specific terminal.

### Active Network

A circuit which contains at least one source of energy is called an active network. An energy source may be a voltage or current source.

### Passive Network

A circuit which contains no energy source is called passive circuit.

### Lumped Network

A network in which all the network elements are physically separable is known as lumped network. Most of the networks are lumped in nature, which consists elements like R,L,C, voltage source etc.

### Distributed Network

A network in which the circuit elements like resistance, inductance etc. cannot be physically separable for analysis purposes, is called distributed network.