Q.

A series LCR circuit with inductance 10 H, capacitance 10 μF, resistance 50 Ω is connected to an AC source of voltage, V=200sin(100t)volt. If the resonant frequency of the LCR circuit is υ0 and the frequency of the AC source is υ, then          [2022]

1 υ0=υ=50Hz  
2 υ0=υ=50πHz  
3 υ0=50πHz,  υ=50Hz  
4 υ=100Hz,  υ0=100πHz  

Ans.

(2)

Here, L=10H;  C=10μF;  R=50Ω;  V=200sin(100t)V

We know that ω=2πυυ=ω2π                                       ...(i)

From eq. (i), υ=1002π=50π  (ω=100rad/s)

   Frequency υ=50πHz

At resonance, υr=υ0=12πLC

=12π10×10×10-6=12π10-4=12π×10-2=1002π=50πHz