AC Circuits

1.  The power factor of an AC circuit is equal to

   A. Cosine of the phase angle

   B. Sine of the phase angle

   C. Unity for a resistive circuit

   D. Unity for a reactive circuit

2.  The power factor of an AC circuit lies between

   A. 0 and 1

   B. -1 and 1

   C. 0 and -1

   D. None of these

3.  A circuit component that oppose the change in the circuit voltage is

   A. Resistance

   B. Capacitance

   C. Inductance

   D. All of the above

4.  In a circuit containing R, L and C, power loss can take place in

   A. C only

   B. L only

   C. R only

   D. All of the above

5.  In any AC circuit always

   A. Apparent power is more than actual power

   B. Reactive power is more than apparent power

   C. Actual power is more than reactive power

   D. Reactive power is more than actual power

 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.  A parallel AC circuit in resonance will

   A. Have a high voltage developed across each inductive and capacitive section

   B. Have a high impedance

   C. Act like a resister of low value

   D. Have current in each section equal to the line current

8.  The frequency of an alternating current is

   A. The speed with which the alternator runs

   B. The number of cycles generated in one minute

   C. The number of waves passing through a point in one second

   D. The number of electrons passing through a point in one second

9.  A pure capacitor connected across an AC voltage consumed 50 V. This is due to

   A. The capacitive reactance in ohms

   B. The current flowing in capacitor

   C. The size of the capacitor being quite big

   D. None of the above

10.  The unit of frequency is

   A. Cycle

   B. Cycle-second

   C. Hertz/second

   D. Hertz

Answer Sheet

1.(A)  2.(A)  3.(B)  4.(C)  5.(A)  6.(B)  7.(B)  8.(C)  9.(D)  10.(D)