Thevenin's theorem principle

Thevenin's Theorem explained

If a resistor of R ohms be connected between any two terminals of a linear network, the resulting steady state current through the resistor is the ratio of the potential difference E0 ( V thevenin ) (between the two points prior to the connection ) and the sum of the values of resistance R0 ( R thevenin )  resistance between the two points. and the connected resistance R. Named after the french telegraph engineer, Charles Leon Thevenin (1857 - 1926).

Thevenin equivalent circuit

Exemple : solve for I3:

Solution :

Step 1 :

Open circuit R3 and solve for the voltage  across the open circuited terminals.

Note :

E0 is computed using any methods (kirchhoff's , maxwell , Nodal , etc .. ) of analysing network problems.

Step 2 :

compute R0 thevenin equivalent resistance or (short circuit all independant voltage sources and open circuits all independant current source ).

Note :

R0 is computed using the basic principles of finding the total resistance of a given circuit.

Step 3 :

construct the thevenin's equivalant circuit and solve the resulting current.