A series LCR circuit with L = 0.12 H, C = 480 nF and  is connected to a 230-V variable-frequency supply. What is the source frequency for which current a amplitude is maximum? Find this maximum value.


Correct option is

4167 rad s–1, 663.5 Hz, 14.14 A



The current amplitude i0 is given by   


It is maximum when , that is, at frequency given by 



This is the resonant angular frequency. The resonant frequency is 


The maximum value of current amplitude is 




A 100-V a.c. source of frequency 500 Hz is connected to a series LCRcircuit with L = 8.1 mH. Find the difference across the resistance.


 capacitor, a 0.3-H inductor and a  resistor are connected in series with a 120-60Hz a.c. source. Calculate the impedance of the circuit.


A circuit containing a 80-mH inductor and a 60- capacitor in series is connected to a 230 V-50 Hz supply. The resistance in the circuit is negligible. Obtain the current amplitude and rms current.  


A series L-C-R circuit having L = 1.5 H,  is connected to a 200-V a.c. supply of variable frequency. When the supply frequency equals the natural frequency of the circuit, find the average power transferred to the circuit in one full cycle. 


An inductor L, a capacitor of  and the resistor of  are connected in series with an a.c. source of frequency 50 Hz. If the current is in phase with the voltage, calculate the inductance of the inductor.


A capacitor, a  resistor and a 80-mH inductor are in series with a 50-Hz a.c source. Calculate the capacitance if the current is in phase with the voltage. 


A series L-C circuit has L = 0.405 H and . The resistance R is zero. Find the frequency of resonance.    


In a series L-C-R circuit connected to a variable frequency 220-V source; we have : L = 4.0 H, . Calculate the resonant frequency of the circuit.   


A variable-frequency 230-V alternating voltage source is connected across a series combination of L = 5.0 H,  and . Calculate the angular frequency of the source which drives the circuit in resonance. 


An L C R circuit has L = 10 mH connected in series to a source of  volt. Calculate the current-amplitude and the average power dissipated per cycle at a frequency 10% lower than the resonant frequency.