The point where those electrons enter an electrical circuit is called the “source” of electrons. The point where the electrons leave an electrical circuit is called the “return” or “earth ground”. The exit point is called the “return” because electrons always end up at the source when they complete the path of an electrical circuit.
The interconnection of electrical component like resistors, inductors, semiconductor devices, transformers and sources of emf is called as a network. The network consist a closed loop, which provides return path for the current. A network may contain one or more circuit elements.
It has two or more terminals for making connection with other circuits.
Types of networks:
There are two types of networks which are given below.
One port network:
The network which has one pair of terminal is called one port network. It helps to reduce the complexity of circuit analysis. In many common electronic devices and circuit blocks such as transistors, amplifiers, electronic filters, and transformers are analyzed in terms of ports. A series, parallel combination of resistors and capacitors are example of one port network.
Two port network:
The network having two pairs of terminal is called a two port network. An amplifier, attenuator, filter, transformers are examples of two port network.