Electronics Circuit

Voltage

 Voltage is a representation of the electrical potential energy per unit charge. if a unit of electrical charge were placed in a location, the voltage indicates the potential energy of it at the point . in orders words, it is a measurement of the energy contained within a electric field or an electric circuit at a given point.

 Voltage is a scalar quantity the SI unit of the voltage is the volt,

   such that  1 volt = 1 joule / coulomb. 

Current:

Electric current is a flow of charge through a media. This type of charge is typically  carried by moving electron in a  wire. The SI unit of current is Ampere . measured by ammeter in series of the circuit.

I = Q/T.

or movement of free electron is called current.

Series -Parallel Circuit

Components of an electrical and electronic circuit can be connected in many different ways. the two simplest of these are called series & parallel . and this type circuit occur very frequently. components connected in series are connected along a single path so the same current flow through all of the components. components connected in parallel are connected  so the same voltage is applied so the same voltage is applied to each component.

A circuit composed solely of components connected in series is known as a series circuit, likewise, one connected completely in parallel is known as a parallel circuit. and series parallel added make a series parallel mix circuit or combine circuit .

Parallel Circuit

A Parallel circuit is a circuit in which there are at least two independent paths in the circuit to get back to the source. in a parallel circuit, the current will flow through the closed paths and not through the open paths.

 


The following rules apply to a parallel circuit:
1) The potential drops of each branch equals the potential rise of the source





2)The total current is equal to the sum of the currents in the branches.

3) The inverses of the total resistance of the circuit (also call effective resistance) is equal to the sum of the inverses of the individual resistances.




Example: Calculate the total resistance of the circuit when R1,R2,R3 are 100 (ohm) and Voltage 1000 v. calculate the total current and each branch  of current and each branch voltage drop and total power of the following figure .

Solution: 

            1/Rt = (1/R1 + 1/R2 + 1/R3) ohm
                    = (1/1oo + 1/100 +1/100) ohm
                    = ( 3/100) ohm
               Rt  = (100/3) ohm
                    = 33.334 ohm

in this circuit total Resistance is 33.334 ohm.

 so total current in this circuit are:
 It = V/Rt
    = 1000 / 33.334
   = 29.99 Amp
or 30.00 amp
in this circuit three resistance value is same so current is equal to each branch
                              3o/3 = 10
   I1= 10 amp.  I2= 10 amp. I3 = 10 amp.

Voltage drop for R1:
 Vr1 = I1* R1 =10*100=1000 Volt
Voltage drop for R2:
 Vr2 =I2* R2 =10*100=1000 Volt
Voltage drop for R3:

 Vr3 =I3* R3 =10*100=1000 Volt
 
Total Power of this circuit is
 P= VI
   = 1000*30
   =30000
   =30.000 KW

  

Series Circuit

Series circuit is which circuit there have only one path of flow electron /current . in this circuit the electrons flow in a counter -clockwise direction, from point 4 to point 3 to point 2 to point 1 and back ground to 4. current is same for all resistance but voltage drop is not same in this circuit.                                                                                                                                                                                                                                                                                                                                                                                                                                            
                      


it have only on path for flow electron so current always must same of each element . so we can write ,
Is=I1=I2=I3=..........................
Voltage drop by each element so
Vs = V1+V2+V3+....................
and the total resistance equation is
Rt=R1+R2+R3+........

Example: If R1=5 ohm, R2=10 ohm, R3=20 ohm and Vs=100 volt. find the total circuit current and each branch voltage drop. and total Power of this circuit.
Solution:
At first calculate total Resistance so ....
 Rt = R1+R2+R3
     = (5+10+20) ohm
     =35 ohm

then calculate source current. (source current = total current = Branch current)
Is =V / Rt
    =100 / 35
    = 2.858 Amp

calculation each branch voltage drop ......
 Vr1 = I*R1 = 2.858 * 5 = 14.29 Volt
 Vr2 = I*R2 = 2.858 *10 = 28.58 Volt
 Vr3 = I*R3 = 2.858 * 20 = 57.16 Volt

 We know from Kirchhoff''s law.......
                                                Rising voltage = Drop voltage 
                                                                100 = 100
                                                              Proved that here.

Total Power of this circuit is
 P  = VI
     = 100*2.858
     = 285.8 Watt.