A 200V variable frequency ac source is connected to series combination of

L = 5H, C = 80µF and R = 40Ω calculate
1)Current amplitude at resonance
2)The power dissipation in the circuit
3) angular frequency of the source to get maximum current in the circuit. Reply fast.


Vrms = 200V

L = 5H

C = 80×10-6F

R = 40Ω


The amplitude of current of a series LCR ckt is given by

Io = V0/√{(XL-XC)2+R2}

At resonance XL=XC


Vo = √2Vrms

Vo = √2×200/R

 => I0 = √2×200/40 = 5√2A


For power with variable frequency

  • -10
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