# Chapter 4: Complex AC Circuits

31. A series LC circuit is resonant at 150 kHz and has a Q of 50. What is the bandwidth?

A. 6 kHz

B. 8 kHz

C. 3 kHz

D. 4 kHz

...
Answer is **(C)**

32. In a series RL circuit supplied with 50 V, the circuit current is measured as 100 mA with a phase angle of 25°. What is the reactive power supplied to the circuit?

A. 3.2 VAR

B. 7.8 VAR

C. 4 VAR

D. 2.1 VAR

**(D)**

33. A coil when connected to an a.c. supply of 200 V, 50 Hz takes 2 A. The power consumed is 200 W. The circuit power factor is

A. 1

B. 2

C. 0.5

D. none of the above

...
Answer is **(C)**

34. If a phasor is multiplied by j, then

A. only its magnitude changes

B. only its direction changes

C. both magnitude and direction change

D. none of the above

...
Answer is **(B)**

**35. The difference of two conjugate numbers results in**

**(A)**

36. The two complex number are given as : 5(cos30°
+j sin30**°**); 10(cosI5**°** + j sin15**°**) The value of product of these two
numbers is equal to

A. 50 (cos 45**°** + j sin 45**°**)

B. 50 (cos 15**°** +j sin 15**°**)

C. 50 (cos 450**°** +j sin 450**°**)

D. none of the above

...
Answer is **(A)**

37. The conductance and susceptance components of admittance are

A. series elements

B. parallel elements

C. series parallel elements

D. none of the above

**... Answer is**

**(B)**

38. The Q-factor of a parallel resonant circuit is given by

A. RLC

B. RC

C. R L

D. None of the above

**... Answer is**

**(B)**

39. At parallel resonance, the circuit draws a current of 2 mA. If the Q of he circuit is 100, then current through the capacitor is

A. 1 mAB. 200 mA

C. 2 mA

D. none of the above

**... Answer is**

**(B)**

40. In a parallel RC circuit with R> Xc, the phase angle will be

A. 45°

B. greater than 45**°**

C. 90**°**

D. insufficient data

...
Answer is **(B)**

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