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
1051. Which of the following motors is preferred for tape-recorders ?
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A. Two value capacitor motor

B. Hysteresis motor

C. Universal motor

D. Shaded pole motor

1052. . In a synchronous motor which loss varies with load ?
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A. Bearing friction loss

B. Windage loss

C. Copper loss

D. Core loss

1053. An induction motor is__________?
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A. self-starting with low torque

B. non-self starting

C. self-starting with high torque

D. self-starting with zero torque

1054. In induction motor, percentage slip depends on__________?
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A. none of the above

B. copper losses in motor

C. supply voltage

D. supply frequency

1055. In a synchronous motor, the magnitude of stator back e.m.f. Eb depends on___________?
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A. load on the motor

B. d.c. excitation only

C. both the speed and rotor flux

D. none of the above

1056. The angle between the rotating stator flux and rotor poles is called _________ angle.
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A. power factor

B. torque

C. obtuse

D. synchronizing

1057. Most of the fractional horsepower motors have either___________?
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A. hard and annealed bearings

B. ball or roller bearings

C. soft and porous bearings

D. plain or sleeve bearings
1058. When V is the applied voltage, then the breakdown torque of a synchronous motor varies as_________?
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A. V312

B. V

C. V2

D. 1/V

1059. Insertion of reactance in the rotor circuit_______?
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A. increases starting torque but maxi-mum torque remains unchanged

B. increases starting torque but maxi-mum torque decreases

C. reduces starting torque as well as maximum torque

D. increases starting torque as well as maximum torque

1060. In three-phase induction motors sometimes copper bars are placed deep in the rotor to___________?
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A. improve efficiency

B. improve power factor

C. reduce copper losses

D. improve starting torque
1061. Change of D.C. excitation of a synchronous motor changes:
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A. all of the these

B. applied voltage of the motor

C. motor speed

D. power factor of power drawn by the motor

E. none of the these

1062. Hysteresis motor is particularly useful for high-quality record players and tape-recorders because___________?
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A. it revolves synchronously

B. it is not subject to any magnetic or mechanical vibrations

C. it can be easily manufactured in extremely small sizes of up to 1 W output

D. it develops hysteresis torque which is extremely steady both in amplitude and phase
1063. In A.C. series motor compensating winding is employed to_____________?
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A. none of the above

B. reduce sparking at the brushes

C. reduce the effects of armature reaction

D. increase the torque

1064. A universal motor can run on___________?
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A. either A.C. or D.C.

B. A.C. only

C. D.C. only

D. none of the above

1065. The speed of a synchronous motor:
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A. increases as the load increases

B. always remains constant

C. decreases as the load decreases

D. none of the above

1066. Which of the following motors will operate at high power factor ?
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A. Capacitor run motor

B. Capacitor start motor

C. Shaped pole motor

D. Split phase motor

1067. A shaded pole motor can be used for_____________?
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A. any of the above

B. circulators

C. hair dryers

D. toys

1068. The maximum speed variation in a 3-phase synchronous motor is____________?
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A. 4 per cent

B. 6 per cent

C. 2. per cent

D. 10 per cent

E. zero
1069. The armature current of the synchronous motor has higher values for_____________?
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A. high excitation only

B. low excitation only

C. both A. and (b)

D. none of the above

1070. The running winding of a single phase motor on testing with meggar is found to be ground. Most probable location of the ground will be___________?
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A. anywhere on the winding inside a slot

B. at the end terminals

C. at the slot edge where coil enters or comes out of the slot

D. at the end connections

1071. Which of the following statements regarding reluctance-start motor is incorrect ?
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A. So far as its basic working principle is concerned, it is similar to shaded pole motor

B. the air-gap between rotor and salient poles is non- uniform

C. It is basically an induction motor and not a synchronous one

D. It is similar to reluctance motor
1072. If a D.C. series motor is operated on A.C. supply, it will____________?
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A. have poor power factor

B. all of the above

C. spark excessively

D. have poor efficiency

1073. The maximum torque in an induction motor depends on___________?
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A. square of supply voltage

B. rotor inductive reactance

C. all of the above

D. frequency

1074. A synchronous motor working at leading power factor can be used as____________?
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A. voltage booster

B. phase advancer

C. noise generator

D. mechanical synchronizer

1075. It is advisable to avoid line starting of induction motor and use starter because____________?
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A. motor takes five to seven times its full load current

B. it will run in reverse direction

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

D. starting torque is very high

1076. If the centrifugal switch of a two-value capacitor motor using two capacitors fails to open then____________?
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A. motor will not come up to speed

B. motor will not carry the load

C. electrolytic capacitor will, in all probability, suffer break down

D. current drawn by the motor will be excessively high

1077. Which of the following statements regarding repulsion-start induction motor is incorrect ?
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A. In fractional horse power motors, it has replaced the capacitor motors

B. It requires more maintenance of commutator and other mechanical devices

C. It makes quite a bit of noise on starting

D. It is not easily reversed

1078. In Ns is the synchronous speed and s the slip, then actual running speed of an induction motor will be___________?
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A. (l-s)Ns

B. s.N,

C. Ns

D. (Ns-l)s

1079. In case of a double cage induction motor, the inner cage has__________?
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A. high inductance arid low resistance

B. low inductance and low resistance

C. low inductance and high resistance

D. high inductance and high resistance

1080. The stating torque of the slip ring induction motor can be increased by adding__________?
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A. external inductance to the rotor

B. external resistance to the rotor

C. external capacitance to the rotor

D. both resistance and inductance to rotor

1081. In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to_______________?
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A. reduce fluctuations in torque

B. increase overload capacity

C. to improve torque

D. improve power factor
1082. Slip rings are usually made of___________?
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A. copper

B. carbon

C. aluminium

D. phospor bronze
1083. In a synchronous motor, the maximum power developed depends on all of the following except:
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A. direction of rotation

B. rotor excitation

C. supply voltage

D. maximum value of coupling angle

1084. When the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop_________________?
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A. inductor motor torque

B. synchronous motor torque

C. induction generator torque

D. d.c. motor toque

E. none of the above

1085. Locked rotor current of a shaded pole motor is____________?
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A. slightly more than full load current

B. several times the full load current

C. equal to full load current

D. less than full load current

1086. The auto-starters (using three auto transformers) can be used to start cage induction motor of the following type__________?
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A. delta connected only

B. star connected only

C. A. and B. both

D. none of the above

1087. A hysteresis motor works on the principle of__________?
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A. magnetisation of rotor

B. hysteresis loss

C. electromagnetic induction

D. eddy current loss

1088. Reduced voltage starter can be used with_____________?
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A. squirrel cage induction motor only but not with slip ring motor

B. none of the above

C. squirrel cage as well as slip ring induction motor

D. slip ring motor only but not with squirrel cage induction motor

1089. If a 3-phase supply is given to the stator and rotor is short circuited rotor will move___________?
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A. in any direction depending upon phase squence of supply

B. in the same direction as the direction of the field

C. in the opposite direction as the direction of the rotating field

1090. Torque developed by a single phase induction motor at starting is_____________?
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A. none of the above

B. uniform

C. nil

D. pulsating

1091. Which motor is normally free from mechanical and magnetic vibrations ?
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A. Universal motor

B. Split phase motor

C. Hysteresis motor

D. Shaded pole motor

1092. The duration of sudden snort-circuit test on a synchronous motor is usually about_____________?
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A. one hour

B. one second

C. none of the above

D. one minute

1093. The starting torque of a three phase induction motor can be increased by__________?
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A. increasing slip

B. increasing current

C. both A. and (b)

D. none of the above

1094. If an induction motor with certain ratio of rotor to stator slots, runs at 1/7 of the normal speed, the phenomenon will be termed as____________?
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A. humming

B. crawling

C. cogging

D. hunting

1095. If any two phases for an induction motor are interchanged_______?
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A. the motor will run in reverse direction

B. the motor will run at reduced speed

C. the motor will burn

D. the motor will not run

1096. Exciters of synchronous machines are______________?
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A. any of the above

B. d.c. compound machines

C. d.c. series machines

D. d.c. shunt machines
1097. Speed control of a universal motor is achieved by__________?
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A. applying variable voltage by means of variable auto-transformer

B. applying variable voltage by means of silicon controlled rectifier

C. all of the above methods

D. connecting rheostat in series

E. varying field flux with tapped field windings

1098. In an induction motor the relationship between stator slots and rotor slots is that_____________?
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A. stator slots are equal to rotor slots

B. stator slots are exact multiple of rotor slots

C. stator slots are not exact multiple of rotor slots

D. none of the above

1099. The magnitude of field flux in a 3-phase synchronous motor?
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A. varies with power factor

B. remains constant at all loads

C. varies with speed

D. varies with the load

1100. A change of 4% of supply voltage to an induction motor will produce a change of approximately ________?
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A. 16% in the rotor torque

B. 4% in the rotor torque

C. 12% in the rotor torque

D. 8% in the rotor torque