15. The active and reactive components of line current of an inductive circuit are equal. The power factor of the circuit is

A.1

B. 0.707 lagging

C. 0.5 lagging

D. 0.866 lagging

16. In an R-L series circuit, the two sides of the impedance triangle that form the phase angle are

A. R and XL

B. R and Z

C. Z and XL

D. none of the above

17. If in an R-L-C series circuit, the frequency is below the frequency, then

A. Xc = XL

B. Xc < XL

C. Xc > XL

D. none of the above

18. At series resonance,

A. circuit impedance is very large

B. circuit power factor is minimum

C. voltage across L or C is zero

D. circuit power factor is unity

19. At series resonance, the voltage across L or C is

A. equal to applied voltage

B. less than applied voltage

C. much more than applied voltage

D. equal to voltage across R

20. The Q factor of a coil is resistance of coil.

A. inversely proportional to

B. directly proportional to

C. independent of

D. none of the above

21. An R-L-C series circuit is connected to a 200 V a.c. source. If Q factor of the coil is 10, then voltage across C at resonance is

A. 200 V

B. 2000 V

C. 20 V

D.210 V

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