A series RLC circuit consists of a resistor of

PHYSICS · Subjective · CBSE · Physics · Alternating Current · Alternating Current

Problem

15\,\Omega

, an inductor of

40\,\text{mH}

and a capacitor of

40\,\mu\text{F}

. It is connected to an AC source of fixed amplitude. (a) Calculate the resonant frequency

f_0

of the circuit. (b) Determine the frequency

f_a

at which the inductive reactance is twice the capacitive reactance (

X_L = 2X_C

) and the frequency

f_b

at which the capacitive reactance is twice the inductive reactance (

X_C = 2X_L

). (c) Compute the impedance of the circuit at

f_a

and at

f_b

. (d) Sketch a qualitative graph of current amplitude versus frequency for the circuit, marking the points corresponding to

f_b

f_0

and

f_a

. (e) Discuss how the phase angle between the source voltage and the current varies at the three marked frequencies.