Question

A series lcr circuit containing a resistance of 120 ohm has angular resonance frequency 4 x 10 at resonance, the voltage across resistance and inductance are 60v and 40v respectively. At frequency the current in the circuit lags the voltage by 45 is equal to x ree 1995

Answer 1

R = 120 Ω

ω = 4 e 3 radians / sec

Vr = 60 V

VL = 40 V

Then potential difference will be:

Vr = IR

60 = I x 120

I = 1/2

VL = I ω L

L = VL / I ω

= 40 / 1/2 x 4 e3

= 20 milli H

At condition of resonance,

ω L = 1 / ωC

C = 1 / ω^2 L

= 1000 / (4 e3)^2 x 20

= 3.125 micro Farad