Circuit theorems – What does Norton's theorem actually state? Statement: Norton's theorem provides a method for reducing any AC circuit to an equivalent that consists of an equivalent voltage source in series with an equivalent impedance. Decide if this statement is correct.

Electrical Engineering Circuit Theorems in AC Analysis Difficulty: Easy
Choose an option
  • A
    True
  • B
    False
  • C
    True only for purely resistive networks
  • D
    True only at one operating frequency

Answer

Correct Answer: False

Explanation

Introduction / Context:Norton's and Thevenin's theorems are dual tools for simplifying linear circuits at a specified frequency. Students often confuse which theorem yields a voltage source in series versus a current source in parallel. This item clarifies that distinction and when each applies in AC analysis with phasors and complex impedances.

Given Data / Assumptions:

  • Linear, bilateral network seen from two terminals at a single frequency (phasor domain).
  • Independent/dependent sources and complex impedances may be present.
  • We want the form defined by Norton's theorem.

Concept / Approach:

Thevenin's theorem: replace the network by V_th in series with Z_th. Norton's theorem: replace the same network by I_n in parallel with Z_n, where Z_n = Z_th and I_n = V_th / Z_th. Therefore, the statement that Norton's theorem yields a voltage source in series is incorrect; that is precisely Thevenin's form.

Step-by-Step Solution:

Find Z_th (or Z_n) by deactivating independent sources and measuring input impedance.Find V_th across the open-circuited terminals.Compute I_n = V_th / Z_th.Form Norton equivalent: a current source I_n in parallel with impedance Z_n = Z_th.

Verification / Alternative check:

Convert between forms: series V_th–Z_th ↔ parallel I_n–Z_n using I_n = V_th / Z_th. Both predict identical terminal behavior, confirming the duality and the incorrectness of the statement.

Why Other Options Are Wrong:

“True” swaps the forms of the two theorems. The qualifiers about resistive networks or single frequency do not fix the misstatement; the topology (series vs. parallel) is still wrong for Norton.

Common Pitfalls:

Memorizing without understanding: Norton → current source in parallel; Thevenin → voltage source in series. Also forgetting that Z_th = Z_n.

Final Answer:

False.

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