A series RLC AC circuit is at resonance.It contains a resistor of 30 W,a capacitor of 0.35 mF and an inductor of 90 mH.If an effective (rms)voltage of 150 V is applied,what is the effective (rms)current when the circuit is in resonance?
A)3.3 A
B)5.0 A
C)9.4 A
D)16.1 A

Question

Quizplus · Accepted Answer

At resonance, the reactances of the inductor and capacitor cancel each other out, leaving only the resistance.

The resonant frequency is given by:

f = 1/(2π√(LC))

Substituting the given values:

f = 1/(2π√(0.35x10^-6 x 90x10^-3)) = 1/(2π x 600) = 265.1 Hz

The impedance of the circuit at resonance is equal to the resistance:

Z = R = 30 Ω

The current flowing through the circuit is given by:

I = V/Z = 150/30 = 5 A (rms)

Therefore, the correct answer is B.

A Series RLC AC Circuit Is at Resonance