The following circuit (shown in Figure) resonates at [Figure description: A series-parallel RLC circuit driven by an AC voltage source at the bottom. Going around the loop from the source: a 10 Ω resistor in series, which then connects to two parallel branches. The top branch consists of a 4 H inductor in series with a 1 F capacitor. The lower branch is a single 1 F capacitor. The two parallel branches rejoin and return to the source.]
- A. all frequencies
- B. 0.5 rad / sec
- C. 5 rad / sec
- D. 1 rad / sec
Answer: B. 0.5 rad / sec
Explanation: At ω = 1/√(LC) = 0.5 rad/s the top branch (4 H + 1 F) is a series resonance (short), so the input impedance is purely R = 10 Ω.