In an LCR circuit at resonance, the a.c. source current is A) maximum in a series LCR circuit only. B) maximum in a parallel LCR circuit only. C) maximum in both series and parallel LCR circuits. D) minimum in both series and parallel LCR circuits. The correct answer is

Step-by-step solution

In a series LCR circuit, the impedance is given by Z = R^2 + (X_L - X_C)^2 . At resonance, X_L = X_C , which makes the impedance minimum ( Z = R ). Since I = V Z , the current is maximum in a series LCR circuit at resonance. In a parallel LCR circuit, the admittance is given by Y = ( 1 R )^2 + ( 1 X_C - 1 X_L )^2 . At resonance, X_L = X_C , which makes the admittance minimum ( Y = 1 R ) and the impedance maximum. Since I = V Y , the current is minimum in a parallel LCR circuit at resonance. Thus, the a.c. source cu