Question

In a series LCR circuit at resonance, the applied e.m.f. of the source and current in the circuit are:

• A. out of phase.
• B. differ in phase by \( \frac{\pi}{2} \) rad.
• C. in phase.
• D. differ in phase by \( \frac{\pi}{4} \) rad.

Hint:

At resonance in a series LCR circuit, the voltage and current are in phase, as the reactances cancel each other out.

Answer 1

The Correct Option is C

Step 1: Understanding Resonance in LCR Circuit.
At resonance, in a series LCR circuit, the inductive reactance \( X_L \) and capacitive reactance \( X_C \) are equal, and thus, the total impedance is purely resistive. The voltage across the components and the current are in phase with each other.
Step 2: Final Answer.
Thus, the applied e.m.f. and the current are in phase at resonance.