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
1001. In an induction motor, no-load the slip is generally____________?
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A. 2%

B. 4%

C. less than 1%

D. 1.50%

1002. If starting winding of a single-phase induction motor is left in the circuit, it will____________?
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A. draw excessive current and overheat

B. run faster

C. run slower

D. spark at light loads

1003. The electric motor used in portable drills is__________?
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A. capacitor run motor

B. universal motor

C. hysteresis motor

D. repulsion motor

1004. In a split phase motor, the running winding should have?
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A. high resistance and low inductance

B. low resistance as well as low inductiance

C. high resistance as well as high inductance

D. low resistance and high inductance
1005. In a capacitor start single-phase motor, when capacitor is replaced by a resistance____________?
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A. torque will increase

B. the motor will consume less power

C. motor will run in reverse direction

D. motor will continue to run in same direction
1006. In capacitor start single-phase motors____________?
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A. none of the above

B. current in the starting winding lags the voltage

C. current in the starting winding leads the voltage

D. current in the starting winding is in phase with voltage in running winding

1007. The purpose of stator winding in the compensated repulsion motor is to_____________?
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A. provide mechanical balance

B. eliminate armature reaction

C. improve power factor and provide better speed regulation

D. prevent hunting in the motor

1008. The armature current of the synchronous motor
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A. any of the above

B. has large values for low and high excitation

C. has large values for high excitation only

D. has large values for low excitation i niy

1009. The shaded pole motor is used for__________?
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A. very high starting torque

B. medium starting torque

C. low starting torque

D. high starting torque

1010. Short-circuiter is used in_____________?
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A. repulsion induction motor

B. none of the above

C. repulsion start induction run motor

D. repulsion motor

1011. In case the air gap in an induction motor is increased?
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A. the windage losses will increase

B. speed of motor will increase

C. the power factor will decrease

D. the magnetising current of the rotor will decrease

1012. The speed of a universal motor is generally reduced by using_________?
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A. gear trains

B. brakes

C. chains

D. V-belts

1013. A 500 kW, 3-phase, 440 volts, 50 Hz, A.C. induction motor has a speed of 960 r.p.m. on full load. The machine has 6 poles. The slip of the machine will be__________?
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A. 0.04

B. 0.01

C. 0.03

D. 0.02

1014. Starting winding of a single phase motor of a refrigerator is disconnected from the circuit by means of a___________?
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A. none of the above

B. magnetic relay

C. thermal relay

D. centrifugal switch

1015. If a single phase induction motor runs slower than normal, the most likely defect is_____________?
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A. worn bearings

B. none of the above

C. short-circuit in the winding

D. open-circuit in the winding

1016. Short-circuit test on an induction motor cannot be used to determine___________?
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A. power scale of circle diagram

B. windage losses

C. copper losses

D. transformation ratio

1017. In repulsion motor direction of rotation of motor____________?
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A. is opposite to that of brush shift

B. is independent of brush shift

C. is the same as that of brush shift
1018. A pump induction motor is switched on to a supply 30% lower than its rated voltage. The pump runs. What will eventually happen ? It will____________?
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A. stall after sometime

B. get heated and subsequently get damaged

C. stall immediately

D. continue to run at lower speed without damage

1019. A 3-phase induction motor delta connected is carrying too heavy load and one of its fuses blows out. Then the motor______________?
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A. will continue running burning its one phase

B. will stop and carry heavy current causing permanent damage to its winding

C. will continue running burning its two phase

D. will continue running without any harm to the winding

1020. The purpose of using short-circuit gear is___________?
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A. none of the above

B. to short circuit the stator phase of motor to form star

C. to short circuit the starting resistances in the starter

D. to short circuit the rotor at slip rings
1021. A synchronous motor will always stop when:______________?
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A. excitation winding gets disconnected

B. load in motor varies

C. supply voltage frequency changes

D. supply voltage fluctuates

1022. In repulsion motor, zero torque is developed when___________?
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A. brush axis is 45 electrical to field axis

B. brush axis coincides with the field axis

C. brush axis is 90 electrical to field axis

D. both B. and (c)
1023. In a split phase motor____________?
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A. the starting winding is connected through a centrifugal switch

B. the running winding is connected through a centrifugal switch

C. both starting and running windings are connected through a centrifugal switch

D. centrifugal switch is used to control supply voltage

1024. An important advantage of a synchronous motor over wound round induction motor is that
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A. its speed may be controlled more easily

B. its speed is independent of supply frequency

C. its power factor may be varied at will

D. none of the above

1025. The maximum value of torque that a synchronous motor can develop without losing its synchronism, is known as_____________?
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A. breaking torque

B. slip torque

C. synchronising torque

D. pull-out torque

1026. In a shaded pole single-phase motor, the revolving field is produced by the use of_________?
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A. inductor

B. capacitor

C. shading coils

D. resistor

1027. A squirrel cage induction motor is not selected when___________?
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A. higher starting torque is the main consideration

B. all above considerations are involved

C. maintenance cost is to be kept low

D. initial cost is the main consideration

1028. In a capacitor start motor, the phase displacement between starting and running winding can be nearly__________?
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A. 60

B. 30

C. 10

D. 90
1029. The circle diagram for an induction motor cannot be used to determine____________?
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A. frequency

B. efficiency

C. power factor

D. output

1030. 5 H.P., 50-Hz, 3-phase, 440 V, induction motors are available for the following r.p.m. Which motor will be the costliest ?
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A. 2880 r.p.m.

B. 1440 r.p.m.

C. 730 r.p.m.

D. 960 r.p.m.

1031. The range of efficiency for shaded pole motors is______________?
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A. 50% to 75%

B. 95% to 99%

C. 80% to 90%

D. 5% to 35%
1032. Size of a high speed motor as compared to low speed motor for the same H.P. will be__________?
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A. any of the above

B. bigger

C. same

D. smaller
1033. Rotor rheostat control method of speed control is used for____________?
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A. squirrel-cage induction motors only

B. slip ring induction motors only

C. both A. and (b)

D. none of the above

1034. In a shaded pole motor, the shading coil usually consist of___________?
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A. a multilayer fine gauge copper wire in parallel with running winding

B. none of the above

C. a single turn of heavy wire which is in parallel with running winding

D. a single turn of heavy copper wire which is short-circuited and carries only induced current
1035. As hysteresis motors are free from mechanical and magnetic vibrations therefore these are considered as suitable for__________?
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A. mixer grinders

B. fans

C. blowers

D. sound equipment
1036. In a single phase motor the centrifugal switch____________?
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A. reconnects the main winding the motor

B. reconnects the auxiliary winding of the motor

C. disconnects main winding of the motor

D. disconnects auxiliary winding of the motor
1037. In case of 3-phase induction motors, plugging means__________?
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A. pulling the motor directly on line without a starter

B. interchanging two supply phases for quick stopping

C. starting the motor on load which is more than the rated load

D. locking of rotor due to harmonics

1038. A schrage motor can run on___________?
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A. zero slip

B. all of the above

C. positive slip

D. negative slip

1039. The value of starting capacitor of a fractional horse power motor will be__________?
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A. 200 uF

B. 400 uF

C. 300 uF

D. 100 uF

1040. For V-curves for a synchronous motor the graph is drawn between:_______________?
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A. terminal voltage and load factor

B. armature current and power factor

C. field current and armature current

D. power factor and field current

1041. A synchronous motor develops maximum power when load angle is____________?
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A. 60

B. 90

C. 45

D. 120

1042. The torque of a rotor in an induction motor under running condition is maximum__________?
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A. at the value of the slip which makes rotor reactance per phase equal to the resistance per phase

B. at the value of the slip which makes the rotor reactance half of the rotor

C. at the zero value of slip

D. at the unit value of slip

1043. A universal motor is one which______________?
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A. runs at dangerously high speed on no-load

B. can be operated either on D.C. or A.C. supply at approximately the same speed and output

C. can be marketed internationally

1044. Which of the following motors has two separate windings on the motor ?
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A. Repulsion start induction run motor

B. Repulsion induction motor

C. Repulsion motor

D. None of the above

1045. The starting torque of a 3-phase squirrel cage induction motor is____________?
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A. 1.5 times the full load torque

B. twice the full load torque

C. equal to full load torque

1046. In split-phase motor auxiliary winding is of___________?
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A. thick wire placed at the top of the slots

B. thin wire placed at the bottom of the slots

C. thick wire placed at the bottom of the slots

D. thin wire placed at the top of the slots
1047. If the centrifugal switch does not open at 70 to 80 percent of synchronous speed of motor, it would result in_________?
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A. damage to the starting winding

B. none of the above

C. overloading of running winding

D. damage to the centrifugal switch

1048. In a universal motor, the most common cause of brush sparking is___________?
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A. high commutator mica

B. shorted armature winding

C. open armature winding

D. all of the above

E. shorted field winding

1049. Which of the following component is usually fabricated out of silicon steel ?
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A. None of the above

B. Shaft

C. Statorcore

D. Bearings

1050. For which of the applications a reluctance motor is preferred ?
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A. Refrigerators

B. Electric shavers

C. Signalling and timing devices

D. Lifts and hoists