CIRCUIT ELEMENTS

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What are the network elements ?
Why we need these ?

     Well, simple questions with explanatory answers !  Not exactly if you keep up the reading.
As we know the ,An Electrical network is an interconnection of electrical components. So there will be a closed path  for current flow through various circuit components to produce the desired function.The electrical components can be broadly classified  to two as follows,
1. Active Components
 In general terms it could be defined as the components with an ability to amplify or process the electrical signal or components having some energy levels to impart.
examples are diode,transistors, scr, opamps etc.
2. Passive Components
   from the concept about the active components its easy to understand whats are passive ones. ie,
The components doesn't having any capability to amplify or process electrical signal its own, but these could support these processes while active components are working on it.
 common examples are resistors,capacitors,inductors

Now this time we could focus on to passive components as these are more common in an electrical power transmission and distribution system.

Resistors

Which are the materials showing the property of resistance, the opposition to flow of electrons or simply current. From the Ohms law we could define in another manner as the resistance offered by the material when a current of I amperes flow through it with a potential of V volt across
ie,                
                                                 R=V/I    (Ohm's Law)
the unit of resistance is ohm(Ω)
 It may found that as  an electric current flows through any conductor, heat will be produced as a result of collision of free electrons with atoms by the action current I and voltage V ,the power absorbed is P=VI =I2R           (Joule heating)
and the energy lost as heat is E=Pt =I2Rt

Inductors
   
    The components showing the property of material by virtue of which it opposes any change in the direction or magnitude of electric current passing through the conductor, the property is called as inductance and having a unit of henry (L), given by Faraday's law of electromagnetic induction.Ie, Inductance is said  to be one henry when the current through a coil of conductor changes at the rate of one ampere per second inducing one volt across the coil.
 We could make an inductor by twisting a conductor into a coil and as soon as the current will flow throgh the coil an electromagnetic field is developed and as there is a change of flow or direction of the current, the field changes resulting a voltage across the coil according to Lenz's Law.
            vL= -Ldi/dt
   A pure inductor stores energy as magnetic field and do not dissipate, and the absorbed energy is 
   E=1/2 Li2

Capacitors

Capacitance is the capability of an element to store electric charge within it.A capacitor  stores electric energy in the form of electric field being established by the two polarities of charges on the two electrodes of a capacitor.Quantitatively capacitance is a measure of charge per unit voltage that can be stored in an element. The unit of capacitance is Farad (F). The capacitance is said to be one farad provided one coulomb  of charge can be stored with one volt across the two electrodes of the element.the element having capacitance is called capacitor.
q being the amount of charge that can be stored in a capacitor of capacitance C against a potential difference of v volts, then
                                                   C=q/v
ie,                  i=C dv/dt

And the energy stored by the capacitor is
                                                        E=1/2 Cv2
now could understand that the voltage across the capacitor being constant, current through it is zero,pointing that on application of dc voltage with no initial charge first it acts as short circuit and as soon as it retains full charge behaves as open circuit

 









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