AC Electrical Circuit Analysis: Thevenin's Theorem

Thevenin's theorem allows us to convert any single port linear bilateral network into an appropriate voltage source (Eth) in series with an appropriate impedance (Zth). Norton's theorem is similar, except that the equivalent consists of a current source (In) in parallel with an impedance (Zn).
Reference: AC Electrical Circuit Analysis, Chapter 5 Section 4.
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[@circletech7745]

Thanks for the help

[@Chris-hi2hn]

Does the Thevenin equivalent circuit still work for a non ideal voltage source? Say your source is a battery, who's voltage output may vary a bit with different loads applied to it. I'm guessing that the Thevenin equivalent may not work if there are dependent components/sources in the substituted part of the circuit.

[@ElectronicswithProfessorFiore]

If it's what I call a first level approximation, the theorem works fine. What I mean by that is a voltage source with an internal resistance. If the model contains non-linear elements, then no, the equivalent may not be accurate.

[@sebperal9672]

R4 is then a load resistor?

[@ElectronicswithProfessorFiore]

It could be (as here) but you can Thevenize from many different perspectives depending on what you want to do. An example would be determining the equivalent resistance that surrounds a coupling capacitor in an amplifier so that you could find the critical frequency. In that case you wouldn't bother with Eth.

[@vaibhavpatil-mj5zj]

In same circuit if L and C would be in parallel then how can we solve it

[@ElectronicswithProfessorFiore]

Conceptually, you would use standard series-parallel techniques, just like you would if it was a DC circuit containing just resistors (the practical difference being the phase angles). If you can solve an AC circuit with a parallel LC combo, this is no different.