Here's a quick introduction to some of the important concepts which will be introduced in this tutorial
1) Classification of a network is done based on the type of elements being used in that network. The operational characteristics of a network depend on the behaviour of its elements. Before going into the contents one should be aware of the following terms used to specify the network, they are described below.
Elements which supply the energy to the circuit are known as active elements. A network which contains active elements is known as active networks. Ex: batteries, generators, transistors etc. Elements which absorb the energy are known as passive elements. A network containing only passive elements is known as passive networks. Ex: resistors, inductors and capacitors.
An element whose operational behaviour is dependent on the direction of flow of current through is known as unilateral elements. Elements like semiconductor diode, which allow the current to pass through them only in one direction.
An element whose behaviour is same irrespective of the direction of flow of current through it is known as bilateral element. Passive elements that allow the current to pass through them in both directions are known as bilateral elements.
Networks consisting of elements which can be physically separated are known as lumped networks. Most of the networks we deal with, are lumped in nature and consists of R, L,C and sources. Networks, like transmission lines, having inseparable elements are known as distributed networks.
A linear element is one which has linear output/input relation and always follows superposition and homogeneity principles. Ohm’s can be applied to such networks.
The element that which does not follow these is known as a nonlinear element. Ohm’s law cannot be applied to such networks.
There are two principal types of source, voltage source and current source. Sources can be either independent or dependent upon some other source quantities.
Independent sources: An independent voltage source (AC or DC) maintains a voltage which is not affected by any other quantity. Similarly an independent current source maintains a current which is unaffected by any other quantity. The usual representation of independent voltage and current source is shown in the tutorial document.
Dependent sources: Some voltage (current) sources have their voltage (current) values varying with some other variables. They are called dependent voltage (current) sources or controlled voltage (current) sources, and their usual representation of dependent sources is as shown in the tutorial document.
VCVS: voltage controlled voltage source: voltage source depends on a voltage value of V1.
VCCS: voltage controlled current source: current source depends on a voltage value of V1.
CCVS: current controlled voltage source: voltage source depends on a current value of I1.
CCCS: current controlled current source: current source depends on a current value of I1.
Superposition Theorem: It states that in an active, linear, bilateral network consisting of active and passive elements with more than one source, the overall response (voltage or current) is equal to the sum of the responses due to each of the sources acting independently.
In any linear network having number of voltage or current sources and resistances, the voltage across or the current through any branch is given by algebraic sum of all the individual voltages or currents caused by each independent source acting alone, with
all other independent voltage sources replaced by short circuits and all other independent current sources replaced by open circuit.
Number of networks to be analyzed = Number of independent sources
Note: the total power delivered to a resistance element must be determined using the total current through or the total voltage across the element and cannot be determined by a simple sum of the power levels established by each source.
Statement: Any two-terminal, linear bilateral network can be replaced by an equivalent network having a single voltage source called Thevenin’s voltage (V Th) and a single series resistance called Thevenin’s resistance (RTh). The Thevenin’s equivalent circuit provides equivalence at the terminals only—the internal construction and characteristics of the original network and the Thevenin’s equivalent are usually quite different.
For finding the thevenin’s resistance, the equivalent resistance across the terminals have to be found with all the independent sources being zero.
Here are kind of the problems which have been solved in the tutorial document :
Related Tutorials ( Introduction to Electrical Circuits - DC ) :