A series circuit initially has resistance and is connected to an ac source of rms voltage
PHYSICS · Subjective · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
A series RLC circuit initially has resistance R1=30Ω and is connected to an ac source of rms voltage 120V. Later, an additional resistor of 20Ω is inserted in series, so that the total resistance becomes R2=50Ω. The inductance and capacitance are unchanged.
(a) For each resistance value, write an expression for the maximum current at resonance.
(b) Calculate the ratio of the maximum currents Imax1/Imax2.
(c) Compute the average power dissipated at resonance before and after the extra resistor is inserted.
(d) Briefly explain how increasing the resistance affects the sharpness of the resonance curve.