This question was asked inGPSC Deputy Executive Engineer (Electrical) Class-2 Master Paper 2026Question 15 of 195 published · Gujarat Public Service CommissionOpen paper
Q15ModerateNetwork Theorems

थेवेनिन प्रमेय (Thevenin’s Theorem) के संबंध में निम्नलिखित कथनों पर विचार कीजिए:
1. थेवेनिन प्रमेय कहता है कि किसी भी रैखिक द्विपक्षीय नेटवर्क को एक प्रतिरोध के श्रेणी में समतुल्य वोल्टेज स्रोत से बदला जा सकता है।
2. थेवेनिन प्रतिरोध सभी स्वतंत्र स्रोतों को निष्क्रिय करके टर्मिनलों से दिखने वाला समतुल्य प्रतिरोध निकालकर ज्ञात किया जाता है।
3. टर्मिनलों पर ओपन सर्किट वोल्टेज नेटवर्क के थेवेनिन वोल्टेज के बराबर होता है।
4. थेवेनिन समतुल्य केवल DC परिपथों के लिए मान्य है और AC परिपथों पर लागू नहीं होता।
उपरोक्त में से कौन-सा/से कथन सही है/हैं?

उत्तर और चरणबद्ध हल
सही उत्तर: C. केवल 1, 2 और 3
संक्षिप्त व्याख्या

C — केवल 1, 2 और 3। V_th = V_OC और Z_th स्वतंत्र स्रोत निष्क्रिय कर पोर्ट से देखा जाता है। थेवेनिन प्रमेय AC पर भी (प्रतिबाधा के साथ) लागू होता है, इसलिए कथन 4 गलत है।

विस्तृत हल (मूल भाषा में)

Statement-wise Verification

  • Statement 1 - Correct.
    Thevenin’s theorem states that any linear bilateral network can be replaced by an equivalent voltage source in series with a resistance.
    Thevenin's theorem replaces a linear two-terminal network by one voltage source Vth in series with an equivalent impedance.
  • Statement 2 - Correct.
    Thevenin resistance is calculated by deactivating all independent sources and finding equivalent resistance seen from terminals.
    V_th=V_OC; Z_th seen at the port with independent sources suppressed.
  • Statement 3 - Correct.
    The open circuit voltage across terminals is equal to Thevenin voltage of the network.
    Vth is the open-circuit terminal voltage.
  • Statement 4 - Incorrect.
    Thevenin equivalent is valid only for DC circuits and cannot be applied to AC circuits.
    Thevenin equivalence also applies in sinusoidal AC networks by using complex impedances

Core Concept

Thevenin's theorem replaces a linear two-terminal network by one voltage source Vth in series with an equivalent impedance. Vth is the open-circuit terminal voltage. For a network with independent sources, Rth/Zth is found by suppressing independent sources; dependent sources remain and may require a test-source method. The theorem applies to AC circuits using complex impedances as well as to DC circuits.

Formula / Key Relationship

V_th=V_OC; Z_th seen at the port with independent sources suppressed.

Why the Other Options Are Wrong

Option A is incorrect because it omits correct statement(s) 1. Option B is incorrect because it includes incorrect statement(s) 4 and omits correct statement(s) 2, 3. Option D is incorrect because it includes incorrect statement(s) 4.

Exam Shortcut / Approach

In AC, use impedances—not just resistances.

Common Mistake

Dependent sources are not turned off when finding Thevenin resistance.

Quick Revision

Thevenin Equivalent Network is linked with Thevenin's Theorem, Network Theorems and Network Theory. In AC, use impedances—not just resistances.

Verified · SRO editorial desk Report
Try it before reading the solution — tap an option.0/1✓ 0✗ 0

More Network Theorems questions