A.C circuit and networks. Part – 3

21. When Q-factor of circuit is high then

A. P.F. Of circuit is high

B. Impedance of circuit is high

C. Band width is large

D. None of the above

22. In a pure inductive circuit, the current will

A. Lag behind the voltage by 90⁰

B. Lead the voltage by 90⁰

C. Remain in phase with the voltage

D. Lag or lead the applied voltage

23. Which of the following statements associated with 3-phase delta connected circuit is true?

A. Line voltage is equal to phase voltage

B. Line current is equal to phase current

C. Line voltage is  time of phase voltage

D. Line currents are 60⁰ apart

24. In a series R-L-C circuit, magnitude of resonance frequency can be changed by changing the value of

A. R only

B. L only            

C. C only

D. L or C

25. In a 3-phase system the EMF are

A. 30⁰ apart

B. 40⁰ apart

C. 90⁰ apart

D. 120⁰ apart

26. What is the relation between time period T and frequency

A. T =frequency

B. T = 1/frequency

C. T = 0.5/frequency

D. T = 0.85/frequency

27. What is apparent power in AC operation?

A. product of voltage and current

B. product of voltage and current at full load

C. product of voltage and current at no load

D. product of RMS voltage and RMS current

28. What is called the instantaneous value of an alternating current

A. The value of peak quantity at any instant

B. The value of alternating quantity at any instant

C. The value of peak current at any instant

D. The value of alternating frequency at any instant

29. What is time period T?

A. time taken by an alternating quantity to complete the +ve half

B. time taken by an alternating quantity to complete the a cycle

C. time taken by an alternating quantity to complete the –ve half

D. time taken by an alternating quantity to reach the peak value

30. Which of the following defined the average value

A. Voltage

B. Heating effect

C. Current

D. Charge transfer