This question was asked inGPSC Deputy Executive Engineer (Electrical) Paper 2024Question 15 of 33 published · Gujarat Public Service CommissionOpen paper
Q38ModerateNetwork Theorems
This question uses a figure from the original paper. The figure is being added; the answer and explanation are already verified.

Consider the following circuit shown in Fig. Q38 and read the following statements.
Statement 1:The current through the capacitor can be obtained by using only source transformation without the use of superposition theorem.
Statement 2:The current through the capacitor can be obtained by using superposition theorem. Fig. Q38Choose the correct option from the following:

Answer & step-by-step solution
Correct answer: C. Statement 2 is correct, but statement 1 is incorrect.
Quick explanation

The network is linear, so superposition can be used by analyzing the response to each sinusoidal source at its own frequency and then adding the time-domain currents. Because the two sources operate at different frequencies and the reactive impedances are frequency-dependent, a single phasor-domain source transformation cannot combine the complete problem without separate frequency analysis. Thus statement 1 is false and statement 2 is true.

iC(t)=iC,ω=2(t)+iC,ω=10(t)

Statement-wise Analysis

Statement 1: False

Statement 2: True

Concept and Reasoning

The network is linear, so superposition can be used by analyzing the response to each sinusoidal source at its own frequency and then adding the time-domain currents. Because the two sources operate at different frequencies and the reactive impedances are frequency-dependent, a single phasor-domain source transformation cannot combine the complete problem without separate frequency analysis. Thus statement 1 is false and statement 2 is true.

Calculation / Key Relation

iC(t)=iC,ω=2(t)+iC,ω=10(t)

Exam Takeaway

Different frequencies → solve separately, then superpose in time.

Common Mistake

Do not add phasors belonging to different frequencies.

Quick Trick

Different frequencies → solve separately, then superpose in time.

Solution diagram – Consider the following circuit shown in Fig. Q38 and read the following…
Exam tipDifferent frequencies → solve separately, then superpose in time.
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