Structure of a Thevenin AC equivalent: A Thevenin AC equivalent always consists of an AC voltage source in series with an equivalent impedance (not a specific capacitance). True or false?

Introduction / Context:
Thevenin equivalents are widely used to simplify linear AC circuits. In the frequency domain, resistors, inductors, and capacitors are represented by complex impedances, and the Thevenin structure remains a voltage source in series with a single equivalent impedance.

Given Data / Assumptions:

• Linear, time-invariant circuit at a fixed frequency.
• Impedances: R, jωL, and 1/(jωC) combine to form a single equivalent Zth.
• Dependent sources are allowed; Zth may be found via test-source methods.

Concept / Approach:

The Thevenin model is always a voltage source Vth in series with Zth. Zth can be resistive, inductive, capacitive, or any complex combination; but it is represented as a single impedance, not as a particular discrete capacitor or inductor unless that happens to be the reduced form.

Step-by-Step Solution:

Verification / Alternative check:

Convert to Norton: In = Vth / Zth and Zn = Zth. Both models must predict identical load behavior, confirming that Thevenin uses a series impedance, not a designated “capacitance.”

Why Other Options Are Wrong:

• “False” would suggest that Thevenin requires a specific capacitor element. In reality, any combination of reactive and resistive effects is lumped into the single equivalent impedance Zth.

Common Pitfalls:

Misinterpreting Zth as a single component. It is a complex number representing the net effect; its physical realization could involve multiple components.

Final Answer:

True