A.C Circuit Theory Objective Questions and Answers - Set 04

Practice Test: Question Set - 04


1. The series and parallel resonance on L-C circuit' differs in that
    (A) Series resistance needs a low-resistance source for sharp rise in current
    (B) Series resonance needs a high-resistance source for sharp increase in current
    (C) Parallel resonance needs a low-resistance source for a sharp increase in impedance
    (D) Parallel resonance needs a low-resistance source for a sharp rise in line current

2. In each of the three coils of a three phase generator, an alternating voltage having an r.m.s. value of 220 V is induced. Which of the following values is indicated by the voltmeters?
    (A) 220 V
    (B) 220 √3 V
    (C) 220/√3 V
    (D) None of the above

3. In a highly capacitive circuit the
    (A) Apparent power is equal to the actual power
    (B) Reactive power is more than the apparent power
    (C) Reactive power is more than the actual power
    (D) Actual power is more than its reactive power

4. The power factor at resonance in R-L-C parallel circuit is
    (A) Zero
    (B) 0.08 lagging
    (C) 0.8 leading
    (D) Unity

5. In a R-L-C circuit
    (A) Power is consumed in resistance and is equal to IR
    (B) Exchange of power takes place between inductor and supply line
    (C) Exchange of power takes place between capacitor and supply line
    (D) All above are correct

6. In an AC. circuit, a low value of kVAR compared with kW indicates
    (A) Low efficiency
    (B) High power factor
    (C) Unity power factor
    (D) Maximum load current

7. Which of the following statements pertains to resistors only?
    (A) Can dissipate considerable amount of power
    (B) Can act as energy storage devices
    (C) Connecting them in parallel increases the total value
    (D) Oppose sudden changes in voltage

8. The power factor of a D.C. circuit is always
    (A) Less than unity
    (B) Unity
    (C) Greater than unity
    (D) Zero

9. The form factor is the ratio of
    (A) Peak value to r.m.s. value
    (B) r.m.s. value to average value
    (C) Average value to r.m.s. value
    (D) None of the above

10. Pure inductive circuit takes power from the A.C. line when
    (A) Applied voltage decreases but current increases
    (B) Applied voltage increases but current decreases
    (C) Both applied voltage and current increase
    (D) Both applied voltage and current decrease

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