Question

In series LCR circuit at resonance, the phase difference between voltage and current is

• A. π
• B. \(\frac{\pi}{4}\)
• C. \(\frac{\pi}{2}\)
• D. zero

Answer 1

The Correct Option is D

Step 1: Resonance condition in an LCR circuit: 

At resonance, the inductive reactance (\(X_L\)) and capacitive reactance (\(X_C\)) become equal:

\[ X_L = X_C \]

Step 2: Implication for circuit impedance:

At resonance, the net reactance is zero. Hence, the impedance (\(Z\)) of the LCR circuit at resonance is purely resistive, equal to \(R\):

\[ Z = R \]

Step 3: Phase difference at resonance:

In a purely resistive circuit, voltage and current are in phase. Thus, the phase difference (\(\phi\)) between voltage and current at resonance is:

\[ \phi = 0 \]

Final Conclusion:
At resonance, the voltage and current in a series LCR circuit are in phase (phase difference = 0).