electrical engineering Mcqs
1. economics of power generation2. analog electronics3. solid state switching circuits4. parallel circuits5. switchgear and protection6. op amp circuits7. transistor audio power amplifiers8. electrostatics9. heating and welding10. multi stage transistor amplifiers11. passive filters12. network theorems13. regulated d c power supply14. a c fundamentals circuits and circuit theory15. electromagnetic induction16. power electronics17. magnetism and electromagnetism18. transformers19. modulation and demodulation20. d c generators21. semiconductor theory22. single phase induction motors23. semiconductor diode24. hybrid parameters25. digital electronics26. oscillators27. earthing or grounding28. single stage transistor amplifiers29. d c motors30. transistor biasing31. amplifiers with negative feedback32. basic electrical33. electronic instruments34. synchronous motors35. field effect transistors fet36. magnetic circuit37. control systems38. industrial drives39. power generation40. series parallel circuits41. transistor tuned amplifiers42. electrical engineering materials43. rectifiers and converters44. integrated circuits45. scr silicon controlled rectifiers46. cables47. polyphase induction motors48. measurement and instrumentation49. transistors50. electrical machine design51. electrolysis and storage of batteries52. electric traction53. transmission and distribution
1101. Burning out of winding is due to___________?
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A. none of the above

B. short circuited capacitor

C. open circuiting of capacitor

D. capacitor value hiving changed

1102. Insertion of resistance in the stator of an induction motor___________?
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A. none of the above

B. decreases the starting torque

C. increases the starting torque

D. increases the load torque

1103. What will happen if the relative speed between the rotating flux of stator and rotor of the induction motor is zero ?
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A. The rotor will run at very high speed

B. The torque produced will be very large

C. The rotor will not run

D. The slip of the motor will be 5%

1104. Slip of an induction motor is negative when_____________?
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A. magnetic field and rotor rotate in opposite direction

B. rotor speed is more than the synchronous speed of the field and are in the same direction

C. rotor speed is less than the synchronous speed of the field and are in the same direction

D. none of the above

1105. In case of a shaded pole motor the direction of rotation of the motor is__________?
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A. from main pole to shaded pole

B. either of the above depending on voltage

C. either of the above depending on power factor

D. from shaded pole to main pole

1106. The speed of a squirrel-cage induction motor can be controlled by all of the following except_____________?
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A. changing supply frequency

B. reducing supply voltage

C. changing winding resistance

D. changing number of poles

1107. In a three-phase induction motor__________?
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A. power factor at starting is low as compared to that while running

B. power factor at starting in the same as that while running

C. power factor at starting is high as compared to that while running

1108. Which of the following motors is used for unity power factor ?
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A. Hysteresis motor

B. Schrage motor

C. Reluctance motor

D. Universal motor

1109. Which of the following motors can be used for unity power factor ?
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A. Shaded pole motor

B. Schrage motor

C. Capacitor run motor

D. Hysteresis motor

1110. In a two value capacitor motor, the capacitor used for running purposes is_______________?
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A. air capacitor

B. paper spaced oil filled type

C. ceramic type

D. a.c. electrolytic type

1111. To reverse the direction of rotation of acapacitor start motor while it is running we should___________?
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A. reverse the direction of connection of the auxiliary winding and after motor comes to rest then connect auxiliary winding to the supply

B. disconnect motor from supply and immediately reconnect it to supply with reversed connections of the main winding

C. disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of main or auxiliary winding

D. reverse the direction of connections of the auxiliary winding and immediately connect it to supply

1112. The crawling in an induction motor is caused by___________?
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A. high loads

B. low voltage supply

C. improper design of machine

D. harmonics developed in the motor
1113. The number of slip rings on a squirrel cage induction motor is usually____________?
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A. two

B. four

C. none

D. three

1114. The injected e.m.f. in the rotor of induction motor must have__________?
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A. zero frequency

B. the same phase as the rotor e.m.f.

C. high value for the satisfactory speed control

D. the same frequency as the slip frequency
1115. Stepless speed control of induction motor is possible by which of the following methods ?
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A. e.m.f. injection in rotor eueuit

B. None of the above

C. Cascade operation

D. Changing the number of poles
1116. Which of the following resistances can be measured by conducting insulation resistance test on a synchronous motor ?
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A. Stator winding to earthed frame

B. Rotor winding to earthed shaft

C. Phase to phase winding resistance

D. All of the above
1117. DOL starting of induction motors is usually restricted to_____________?
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A. high horsepower motors

B. variable speed motors

C. high speed motors

D. low horsepower motors
1118. The motor used for the compressors is____________?
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A. shaded pole motor

B. d.c. series motor

C. capacitor-start capacitor-run motor

D. reluctance motor

1119. Which of the following motor will give relatively high starting torque ___________?
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A. Split phase motor

B. Capacitor start motor

C. Capacitor run motor

D. Shaded pole motor

1120. In squirrel cage induction motors, the rotor slots are usually given slight skew in order to__________?
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A. reduce eddy currents

B. reduce accumulation of dirt and dust

C. reduce windage losses

D. reduce magnetic hum
1121. Two-value capacitor motor finds increased application as compressor motor in small home air-conditioners because_____________?
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A. it is comparatively cheaper

B. it has almost non-destructible capacitor

C. it has low starting as well as running currents at relatively high power factor

D. it is quiet in operation

1122. In split phase motor main winding is of _____________?
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A. thin wire placed at the top of the slots

B. thick wire placed at the top of the slots

C. thick wire placed at the bottom of the slots

D. thin wire placed at the bottom of the slots

1123. If the capacitor of a single-phase motor is short-circuited_________?
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A. the motor will run

B. the motor will not start

C. the motor will run in reverse direction

D. the motor will run in the same direction at reduced r.p.m

1124. If one-phase of a 3-phase synchronous motor is short-circuited, motor will ______________?
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A. will refuse to start

B. will overheat in spots

C. will fail to pull into step

D. will not come upto speed

1125. The power factor of a synchronous motor is better than that of induction motor because
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A. mechanical load on the motor can be adjusted

B. stator supply is relieved of responsibility of producing magnetic field

C. synchronous motor has large air gap

D. synchronous motor runs at synchronous speed

1126. Which of the following motors is used in tape-recorders ____________?
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A. Capacitor-run motor

B. Reluctance motor

C. Universal motor

D. Hysteresis motor
1127. Centrifugal switch disconnects the auxiliary winding of the motor at about ______ percent of synchronous speed?
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A. 30 to 40

B. 80 to 90

C. 70 to 80

D. 100

1128. The speed control of universal motor used for sewing machines is by____________?
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A. centrifugal mechanism

B. friction

C. tapping the field

D. varying the resistance
1129. For which motor the speed can be controlled from rotor side ?
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A. Squirrel-cage induction motor

B. Slip-ring induction motor

C. Both A. and (b)

D. None of the above

1130. In the circle diagram for induction motor, the diameter of the circle represents____________?
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A. line voltage

B. rotor current

C. slip

D. running torque

1131. Direction of rotation of a split phase motor can be reversed by reversing the connection of__________?
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A. running winding only

B. starting winding only

C. either A. or (b)

D. both A. and (b)

1132. While starting a synchronous motor by induction motor action, field winding is usually_____________?
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A. none of the above

B. connected to D.C. supply

C. short-circuited by low resistance

D. kept open-circuited

1133. The speed characteristics of an induction motor closely resemble the speedload characteristics of which of the following machines?
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A. D.C. shunt motor

B. none of the above

C. D.C. series motor

D. universal motor

1134. Which of the following statements regarding hysteresis motor is in incorrect?
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A. It is extremely sensitive to fluctuations in supply voltage

B. It accelerates from rest to full-speed almost instantaneously

C. It is extremely quiet in operation

D. Its high starting torque is due to its high rotor hysteresis loss

1135. When a 3-phase synchronous generator is supplying a zero power factor lagging load, the armature field affects the main field in the following way
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A. directly opposes it

B. cross-magnetises it

C. augments it directly

D. none of the above

1136. Which of the following methods is easily applicable to control the speed of the squirrel-cage induction motor _____________?
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A. Rotor rheostat control

B. By injecting e.m.f. in the rotor circuit

C. By changing the number of stator poles

D. By operating two motors in cascade

1137. The rotor slots, in an induction motor, are usually not quite parallel to the shaft because it_____________?
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A. improves the efficiency

B. improves the power factor

C. helps the rotor teeth to remain under the stator teeth

D. helps in reducing the tendency of the rotor teeth to remain under the stator teeth
1138. The rotor of a hysteresis motor is made of___________?
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A. aluminium

B. chrome steel

C. copper

D. cast iron

1139. Which of the following single-phase motors is suitable for timing and control purposes ?
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A. Reluctance motor

B. Repulsion motor

C. Series motor

D. Universal motor

1140. It is advisable to avoid line-starting of induction motor and use starter because__________?
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A. starting torque is very high

B. it will pick-up very high speed and may go out of step

C. motor takes five to seven times its full load current

D. it will run in reverse direction

1141. Insertion of resistance in the rotor of an induction motor to develop a given torque?
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A. increases the rotor current

B. decreases the rotor current

C. rotor current becomes zero

D. rotor current rernains same
1142. The complete circle diagram of induetion motor can be drawn with the help of data found from__________?
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A. blocked rotor test

B. stator resistance test

C. noload test

D. all of the above
1143. An induction motor is identical to_________?
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A. asynchronous motor

B. D.C. compound motor

C. synchronous motor

D. D.C. series motor

1144. The good power factor of an induction motor can be achieved if the average flux density in the air gap is___________?
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A. large

B. absent

C. small

D. infinity

1145. Which type of load is offered by cranes and hoists ?
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A. Reversing, heavy start

B. Reversing, light start

C. Gradually varying load

D. Non-reversing, no-load start

1146. In repulsion motor, maximum torque is developed when____________?
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A. brush axis is at 45 electrical to the field axis

B. none of the above

C. brush axis is at 90 electrical to the field axis

D. brush axis coincides with the field axis

1147. A three-phase synchronous motor will have_____________?
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A. no slip-rings

B. three slip-rings

C. two slip-rings

D. one slip-ring

1148. A 3-phase slip ring motor has____________?
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A. wound rotor

B. short-circuited rotor

C. double cage rotor

D. any of the above

1149. Lubricant used for ball bearing is usually___________?
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A. mineral oil

B. molasses

C. graphite

D. grease
1150. In medium sized induction motors, the slip is generally around___________?
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A. 0.40%

B. 14%

C. 0.04%

D. 4%