MCQs on RLC Circuit

MCQs on RLC Circuit

Q1: A 6.8 kΩ resistor, a 7 mH coil, and a 0.02 μF capacitor are in parallel across a 17 kHz ac source. The coil’s internal resistance Rw is 30 Ω. The equivalent parallel resistance, Rp (eq) is

1. 1,878 Ω
2. 18,780 Ω
3. 18,750 Ω
4. 626 Ω

Answer: (b) 18,780 Ω

Q2: A 15 kΩ resistor, a 220 μH coil, and a 60 pF capacitor are in series across an ac source. What is the bandwidth of the circuit?

1. 138 MHz
2. 10,866 Hz
3. 1,907 Hz
4. 138 kHz

Answer: (b) 10,866 Hz

Q3: A 90 Ω resistor, a coil with 30 Ω of reactance, and a capacitor with 50 Ω of reactance are in series across a 12 V ac source. The current through the resistor is

1. 9 mA
2. 90 mA
3. 13 mA
4. 130 mA

Answer: (d) 130 mA

Q4: The total impedance, expressed in polar form for a certain series RLC circuit with a 200 Hz, 15 V ac source has the following values: R = 12 Ω, C = 80 μF, and L= 10 mH is

1. 12.28 ㄥ12.34⁰ Ω
2. 12.57 ㄥ12.34⁰ Ω
3. 9.95 ㄥ12.34⁰ Ω
4. 12.62 ㄥ12.34⁰ Ω

Answer: (a) 12.28 ㄥ12.34⁰ Ω

Q5: If the resistance in parallel with a parallel resonant circuit is reduced, the bandwidth

1. Disappears
2. Becomes Sharper
3. Increases
4. Decreases

Answer: (d) Decreases

Q6: To tune a parallel resonant circuit to a higher frequency, the capacitance should be

1. Increased
2. Decreased
3. Left alone
4. Replaced with inductance

Answer: (b) Decreased

Q7: A 15 Ω resistor, an inductor with 8 Ω inductive reactance, and a capacitor with 12 Ω capacitive reactance are in parallel across an ac voltage source.

1. 12.7 Ω
2. 127 Ω
3. 4.436 Ω
4. 6,174 Ω

Answer: (a) 12.7 Ω

Q8: What is the value of resonant frequency if the value of C in a series RLC circuit is decreased?

1. Is not affected
2. Increases
3. Is reduced to zero
4. Decreases

Answer: (b) Increases

Q9: In a series RLC circuit that is operating above the resonant frequency the current

1. Lags the applied voltage
2. Leads the applied voltage
3. Is in phase with the applied voltage
4. Is zero

Answer: (a) Lags the applied voltage

Q10: An inductor with a reactance of 120 Ω, a capacitor with a reactance of 120 Ω and a 24 Ω resistor are in series across a 60 V source. The circuit is at resonance. The voltage across the inductor is

1. 60 V
2. 660 V
3. 30 V
4. 300 V

Answer: (d) 300 V