Physics · Reactance and impedance, LCR series circuit, resonance, power in AC circuits, wattless current
Assertion In series circuit, current and voltage are in same phase at resonance.
Assertion In series \( \boldsymbol{L}-\boldsymbol{C}-\boldsymbol{R} \boldsymbol{A} \boldsymbol{C} \) circuit, current and voltage are in same phase at resonance. Reason In series \( \boldsymbol{L}-\boldsymbol{C}-\boldsymbol{R} \boldsymbol{A} \boldsymbol{C} \) circuit, resonant frequency does not depend on the value of resistance. Hence current, at resonance, does not depend on resistance.
- A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
- B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
- C. Assertion is correct but Reason is incorrect
- D. Both Assertion and Reason are incorrect
Step-by-step solution
At resonance in a series LCR circuit, inductive reactance equals capacitive reactance, so impedance is purely resistive and current is in phase with voltage. The resonant frequency indeed does not depend on resistance. However, the current at resonance is V/R, which does depend on resistance. Hence the Reason's conclusion is false.
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