THEVENIN EQUIVALENT

Any two terminal linear network containing energy sources & impedances can be replaced by an equivalent circuit consisting a voltage source(V1) in series with an impedance(Rt). R = Z V1 : Open circuit voltage at 11^(Z4=0),(R2=0) Zt : Impedance measured with all sources eliminated & not their Impedances. Current through Z4 is same for both the circuits.