thevenin and Northon theorem

Thevenin and Northon theorem

-Thevenin’s theorem  says that the linear two-terminal  circuit can be replaced by an equivalent circuit consist of voltage source Vth in series with a resistor Rth.

-It is a method for the reduction of a portion of a complex circuit into a simple one. this mean that the single voltage source and series resistor must behave identically to the actual network it is replacing.

steps:

          -We will turn of all independent sources and shorting the terminals of voltage source and open terminals in the current source and Rth or the Zth is the input impedance of the network between the terminal a and b.

           -By removing all independent source solve the total impedance in the terminal a and b to obtain the Rth or Zth and simply voltage division we can solve Vth but it depends on the scenario.

-Northon's theorem says that linear two-terminal circuit can be replace by an equivalent circuit consist of current source which is I n parallel with resistors.

-Replacing a network by its northon equivalent can simplify the analysis of a complex circuit. in this example, the northon current is obtained from the open circuit voltage (the thevenin voltage) divided by the resistance R. The resistance is the same in the thevenins resistance.

northon and thevenin equivalent formula:

                                Rn = Rth

                                I n = Vth/Rth

                                Vth = (I n) (R n)