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
1151. Which of the following statements regarding a reluctance motor is incorrect ?
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A. Its squirrel cage-rotor is of unsym-metrical magnetic construction in order to vary reluctance path between stator and rotor

B. It is nothing else but a single-phase, salient pole synchronous-induction motor

C. It cannot be reversed, ordinarily

D. It requires no D.C. field excitation for its operation

1152. Which of the following single-phase induction motors is generally used in time phonographs ?
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A. Resistance start

B. Shaded pole

C. Capacitor start capacitor run

D. Universal

1153. Which is of the following data is required to draw the circle diagram for an induction motor ?
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A. Block rotor test only

B. No load test only

C. Block rotor test and no-load test

D. Block rotor test, no-load test and stator resistance test
1154. The rotor copper losses, in a synchronous motor, are met by____________?
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A. motor input

B. armature input

C. d.c. source

D. supply lines

1155. The motor used on small lathes is usually_________?
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A. D.C. shunt motor

B. single-phase capacitor run motor

C. universal motor

D. 3-phase synchronous motor

1156. In a A.C. series motor armature coils are usually connected to commutator____________?
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A. through capacitors

B. solidly

C. through resistance

D. through reactances

1157. The capacitors used in single-phase capacitor motors have no__________?
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A. definite value

B. dielectric medium

C. polarity marking

D. voltage rating

1158. As load on an induction motor goes on increasing______________?
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A. its power factor remains constant

B. its power factor goes on decreasing

C. its power factor goes on increasing even after full load

D. its power factor goes on increasing up to full load and then it falls again
1159. Blocked rotor test on induction motors is used to find out?
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A. leakage reactance

B. all of the above

C. power factor on short circuit

D. short-circuit current under rated voltage

1160. Slip ring motor is preferred over squirrel cage induction motor where___________?
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A. load torque is heavy

B. all of the above

C. high starting torque is required

D. heavy pull out torque is required

1161. In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will_____________?
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A. fall out of synchronism and come to stand still

B. draw excessive armature current and may burn out

C. become unstable

D. run as induction motor
1162. When the equivalent circuit diagram of doouble squirrel-cage induction motor is constructed the two cages can be considered__________?
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A. in parallel with stator

B. in parallel

C. in series

D. in series-parallel

1163. Star-delta starting of motors is not possible in case of____________?
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A. low horse power motors

B. high speed motors

C. variable speed motors

D. single phase motors
1164. An induction motor with 1000 r.p.m. speed will have____________?
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A. 6 poles

B. 4 poles

C. 8 poles

D. 2 poles

1165. The power factor of a single-phase induction motor is usually?
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A. unity

B. lagging

C. unity to 0.8 leading

D. always leading

1166. The cogging of an induction motor can be avoided by____________?
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A. proper ventilation

B. using DOL starter

C. auto-transformer starter

D. having number of rotor slots more or less than the number of stator slots (not equal)
1167. Which of the following applications always have some load whenever switched on ?
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A. Fan motors

B. Pistol drills

C. All of the above

D. Vacuum cleaners

1168. A synchronous motor connected to infinite bus-bars has at constant full load, 100% excitation and unity power factor. On changing the excitation only, the armature current will have_____________?
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A. leading power factor with under-excitation

B. lagging power factor with over-excitation

C. no change of power factor

D. leading power factor with over-excitation
1169. A.C. series motor as compared to D.C. series motor has__________?
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A. more number of armature turns

B. less air gap

C. less number of field turns

D. all of the above

E. smaller brush width

1170. Which of the following motors has highest starting torque ?
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A. Capacitor-start motor

B. Split-phase motor

C. Shaped pole motor

D. Repulsion motor

1171. An over-excited synchronous motor takes__________?
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A. leading current

B. lagging current

C. both A. and (b)

D. none of the above

1172. In a three-phase induction motor, the number of poles in the rotor winding is always__________?
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A. more than the number of poles in stator

B. zero

C. less than number of poles in stator

D. equal to number of poles in stator
1173. The effect of increasing the load on a synchronous motor running with normal excitation is to___________?
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A. decrease both armature current and power factor

B. decrease armature current but increase power factor

C. increase armature current but decrease power factor

D. increase both its armature current and power factor

1174. Single phase induction motor usually operates on__________?
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A. 0.8 power factor lagging

B. 0.6 power factor lagging

C. unity power factor

D. 0.8 power factor leading

1175. The efficiency of an induction motor can be expected to be nearly____________?
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A. 99%

B. 60 to 90%

C. 80 to 90%

D. 95 to 98%

1176. In the squirrel-cage induction motor the rotor slots are usually given slight skew__________?
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A. to increase the tensile strength of the rotor bars

B. none of the above

C. to ensure easy fabrication

D. to reduce the magnetic hum and locking tendency of the rotor
1177. Which of the following statements regarding single-phase induction motors correct?
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A. It can rotate in one direction only

B. It is self-starting

C. It is not self-starting

D. It requires only one winding

1178. The speed of a universal motor is usually reduced by using____________?
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A. chains

B. belts

C. brakes

D. gearing
1179. The mechanical displacement of the rotor with respect to the stator, in polyphase multipolar synchronous motors running at full load, is of the order of_____________?
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A. two degrees

B. five degrees

C. zero degree

D. ten degrees

1180. The crawling in the induction motor is caused by____________?
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A. high loads

B. improper design of the machine

C. low voltage supply

D. none of the above

E. harmonics develped in the motor
1181. When /?2 is the rotor resistance, .X2 the rotor reactance at supply frequency and s the slip, then the condition for maximum torque under running conditions will be_____________?
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A. R2 = s2X2

B. R2 = sX2

C. sR2 = X2

D. sR2X2 = 1

1182. A shaded pole motor does not possess___________?
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A. capacitor

B. all of the above

C. commutator

D. centrifugal switch

1183. Which of the following motors is non-self starting ?
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A. Squirrel cage induction motor

B. Wound round induction motor

C. D.C. series motor

D. synchronous motor
1184. Speed torque characteristic of a repulsion induction motor is similar to that of a D.C____________?
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A. compound motor

B. separately excited motor

C. shunt motor

D. series motor

1185. Which type of bearing is provided in small induction motors to support the rotor shaft ?
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A. Cast iron bearings

B. Bush bearings

C. None of the above

D. Ball bearings
1186. The direction of rotation of an hysteresis motor is determined by____________?
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A. position of shaded pole with respect to main pole

B. none of these

C. interchanging the supply leads

D. retentivity of the rotor material

1187. Which motor is preferred for use in mines where explosive gases exist ?
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A. Synchronous motor

B. D.C. shunt motor

C. Air motor

D. Induction motor

1188. Which of the following motors is used in mixies ?
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A. Hysteresis motor

B. Repulsion motor

C. Reluctance motor

D. Universal motor
1189. After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on ______________?
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A. compensating winding

B. field winding

C. running winding

D. rotor winding

1190. In case the air gap in an induction motor is increased____________?
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A. the power factor will decrease

B. speed of motor will increase

C. the magnetising current of the rotor will decrease

D. the windage losses will increase

1191. Hunting in a synchronous motor cannot be due to___________?
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A. variable frequency

B. variable supply voltage

C. windage friction

D. variable load

1192. The power developed by a synchronous motor will be maximum when the load angle is____________?
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A. 45

B. 120

C. zero

D. 90
1193. Riunting in a synchronous motor takes place___________?
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A. when load varies

B. when supply voltage fluctuates

C. motor is under loaded

D. when power factor is unity

1194. Which of the following plants is almost inevitably used as base load plant?
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A. Pumped storage plant

B. Gas turbine plant

C. Diesel engine plant

D. Nuclear power plant
1195. The torque angle, in a synchronous motor, is the angle between_______________?
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A. none of the above

B. the supply voltage and the back e.m.f.

C. the rotating stator flux and rotor poles

D. magnetising current and back e.m.f.

1196. Which of the following, in a thermal power plant, is not a fixed cost?
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A. Fuel cost

B. Depreciation

C. Insurance charges

D. Interest on capital

1197. Which of the following generating station has minimum running cost ?
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A. Diesel

B. Nuclear

C. Thermal

D. Hydro
1198. If the field of a synchronous motor is underexcited, the power factor will be_____________?
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A. lagging

B. zero

C. unity

D. leading

1199. ___________ will offer the least load.
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A. Hair dryer

B. Electric shaver

C. Television

D. Vacuum cleaner

1200. A capacitor is generally a____________?
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A. bilateral and active component

B. non-linear and active component

C. linear and bilateral component

D. active, passive, linear and nonlinear component