Which graph shows the correct variation of r.m.s. current ' i ' with frequency ' f ' of a.c. in case of series resonant circuit ?

Step-by-step solution

In a series LCR circuit, the impedance is given by: Z = R^2 + (X_L - X_C )^2 = R^2 + (2 f L - 1 2 f C )^2 The r.m.s. current is: i = V_ rms Z At the resonant frequency f_r = 1 2 LC , the inductive reactance equals the capacitive reactance ( X_L = X_C ). At this point, the impedance Z is minimum ( Z = R ) and the current i is maximum. For frequencies f For frequencies f > f_r , Z increases again and i decreases. Thus, the graph of current i versus frequency f is a bell-shaped curve with a peak at the resonant freque