In the RLC series circuit shown in figure, resonance occurs when the value of C is 20 µF. The supply voltages is v(t) = 20 sin (500t) V. Find the value of L.

• A. 5 H
• B. 0.2 H
• C. 5 mH
• D. 0.2 mH

Answer: (B)

Here,
ω = 500 rad/sec = 2πf.
At Resonance condition,
ωL = 1/(ωC)
L 0.2 H
Also at series resonace
1. fr = 1/[2π√(LC)]
2. PF = 1
3. Maximum current
4. Source voltage = voltage across resistor.