Explore topic-wise MCQs in Electrical Engineering Questions.

This section includes 122 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.

101.

When the excitation of an unloaded salient pole synchronous motor suddenly gets disconnected______________?
A. the motor stops
B. it runs as a reluctance motor at the same speed
C. it runs as a reluctance motor at a lower speed
D. none of the above
Answer» B. it runs as a reluctance motor at the same speed
Discussion
102.

A synchronous motor can be used as a synchronous capacitor when it is____________?
A. under-loaded
B. over-loaded
C. under-excited
D. over-excited
Answer» E.
Discussion
103.

A synchronous motor can be started by________?
A. pony motor
B. D.C. compound motor
C. providing damper winding
D. any of the above
Answer» E.
Discussion
104.

A pony motor is basically a_________?
A. small induction motor
B. D.C. series motor
C. D.C. shunt motor
D. double winding A.C./D.C. motor
Answer» B. D.C. series motor
Discussion
105.

Mostly, synchronous motors are of_____________?
A. alternator type machines
B. induction type machines
C. salient pole type machines
D. smooth cylindrical type machines
Answer» D. smooth cylindrical type machines
Discussion
106.

When V is the applied voltage, then the breakdown torque of a synchronous motor varies as_________?
A. V
B. V312
C. V2
D. 1/V
Answer» B. V312
Discussion
107.

The working of a synchronous motor is similar to_____________?
A. gear train arrangement
B. transmission of mechanical power by shaft
C. distribution transformer
D. turbine
E. none of the above
Answer» C. distribution transformer
Discussion
108.

The back e.m.f. of a synchronous motor depends on______________?
A. speed
B. load
C. load angle
D. all of the above
Answer» D. all of the above
Discussion
109.

In a synchronous motor, the magnitude of stator back e.m.f. & depends on_______________?
A. d.c. excitation only
B. speed of the motor
C. load on the motor
D. both the speed and rotor flux
Answer» B. speed of the motor
Discussion
110.

The shaft of synchronous motor is made of____________?
A. mild steel
B. chrome steel
C. alnico
D. stainless steel
Answer» B. chrome steel
Discussion
111.

A synchronous motor can be made self starting by providing?
A. damper winding on rotor poles
B. damper winding on stator
C. damper winding on stator as well as rotor poles
D. none of the above
Answer» E.
Discussion
112.

The maximum power developed in a synchronous motor occurs at a coupling angle of____________?
A. 30°
B. 60°
C. 90°
D. 180°
Answer» D. 180°
Discussion
113.

The operating speed of a synchronous motor can be changed to new fixed value by___________?
A. changing the load
B. changing the supply voltage
C. changing frequency
D. using brakes
Answer» D. using brakes
Discussion
114.

In which of the following motors the stator and rotor magnetic field rotate at the same speed?
A. Universal motor
B. Synchronous motor
C. Induction motor
D. Reluctance motor
Answer» C. Induction motor
Discussion
115.

A synchronous motor running with normal excitation adjusts to load increases essentially by increase in______________?
A. back e.m.f.
B. armature current
C. power factor
D. torque angle
Answer» C. power factor
Discussion
116.

The efficiency of a properly designed synchronous motor will usually fall in range___________?
A. 60 to 70%
B. 75 to 80%
C. 85 to 95%
D. 99 to 99.5%
Answer» D. 99 to 99.5%
Discussion
117.

The armature current of the synchronous motor has higher values for_____________?
A. high excitation only
B. low excitation only
C. both A. and (b)
D. none of the above
Answer» D. none of the above
Discussion
118.

The synchronous motor is not inherently self-starting because_______________?
A. the force required to accelerate the rotor to the synchronous speed in an instant is absent
B. the starting device to accelerate the rotor to near synchronous speed is absent
C. a rotating magnetic field does not have enough poles
D. the rotating magnetic field is produced by only 50 Hz frequency currents
Answer» B. the starting device to accelerate the rotor to near synchronous speed is absent
Discussion
119.

A synchronous motor working at leading power factor can be used as____________?
A. voltage booster
B. phase advancer
C. noise generator
D. mechanical synchronizer
Answer» C. noise generator
Discussion
120.

An over-excited synchronous motor takes__________?
A. leading current
B. lagging current
C. both A. and (b)
D. none of the above
Answer» B. lagging current
Discussion
121.

Power factor of a synchronous motor is unity when_____________?
A. the armature current is maximum
B. the armature current is minimum
C. the armature current is zero
D. none of the above
Answer» C. the armature current is zero
Discussion
122.

A three-phase synchronous motor will have_____________?
A. no slip-rings
B. one slip-ring
C. two slip-rings
D. three slip-rings
Answer» D. three slip-rings
Discussion