What is amplifier explain the working of common emitter amplifier necessary diagram ? || What is amplifier || important inter physics questions || physics interesting question || define amplifier

 *** What is amplifier explain the working of common emitter amplifier necessary diagram ? 

Amplifier:- The process raising strength of a week input signal is known as amplification.

        The device used for these is called amplifier.

Amplifier are two types :-

1) Voltage amplifier

2) Power amplifier

1) Voltage amplifier :-  The process of raising voltage level by the amplifier is called voltage amplifier.

2) Power Amplifier :- The process raising power of the amplifier is called power amplifier.

Working :- When an AC input signal VI is super imposed an the baise out is taken between collector and ground.

Circuit :-

Apply Kirchhoff's Voltage law for input loop

VBB = IB.RB + VBE.       Equestion -1

For output loop

VCC = ICRC + VCE.      Equestion -2

VBB+ Vin = IB.RB + VBE + ∆IB ( RB + r )

Vin = ∆ IB ( RB + r ).      ( *RB is constant)

                                          ( RB = 0 )

Vin is a function of "r" 

So 

Vin = ∆IB .r.    Equestion-3

if Vcc is Constant then VCE = Vout

Vcc  = Ic Rc + VCE

0      = ∆ IcRc + Vout

Vout =  - ∆ Ic Rc.      Equestion -4

                                  

Voltage gain Av = Output Voltage/Input voltage

                                  

           Av = Vout/ Vin

        Av= - [ ∆Ic ] Rc / [ ∆ IB ]r

       

           Av =  - β Rc / r

            Av = - β RL / r

***  Voltage gain =  - current gain  RL / r