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
7051. The winding where dummy coils are used is sometimes called______________?
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A. triplex winding

B. none of the above

C. duplex winding

D. forced winding
7052. The time taken by the machine to attain 0.632 of its final steady temperature rise is called_____________?
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A. cooling time constant

B. heating time constant

C. none of the above

D. either A. or B.

7053. The cold rolled grain oriented steel has _________ permeability in the direction of the grain orientation?
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A. maximum

B. minimum

C. none of the above

D. nil

7054. Which of the following is the commonly used type of electromagnets ?
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A. All of the above

B. Horse shoe type

C. Flat-faced armature type

D. Flat-faced plunger type

7055. The operation of a D.C. machine with large air gap lengths is comparatively_____________?
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A. quiet

B. either of the above

C. noisy

D. none of the above

7056. The stator of a D.C. machine comprises of_____________?
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A. interpoles

B. frame

C. main poles

D. all of the above
7057. is usually used for brush rockers____________?
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A. Aluminium

B. Cast-iron

C. Mild steel

D. Copper

7058. By which of the following methods motor rating for variable load drives can be determined ?
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A. Equivalent power method

B. Equivalent torque method

C. Equivalent current method

D. Method of average losses

E. All of the above
7059. In D.C. machines, the ________ in field mmf results in increase in size and cost of machines?
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A. either of the above

B. decrease

C. increase

D. none of the above

7060. Which of the following is the basic consideration in the design of insulation ?
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A. Electrical considerations

B. Thermal considerations

C. All of the above

D. Mechanical considerations

7061. Cylindrical windings using circular conductors, employed in transformers, are_____________?
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A. double layered

B. single layered

C. none of the above

D. multi-layered
7062. Which of the following brushes can be used for high values of current density ?
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A. Electro-graphitic brushes

B. Natural graphite brushes

C. Hard carbon brushes

D. Metal graphite brushes
7063. The resistivity of water should not be less than_____________?
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A. 2000 Q m

B. 10 Q m

C. 1000 Q m

D. 100 Q m

7064. Which of the following is the major consideration to evolve a good design?
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A. Cost

B. Durability

C. Compliance with performance criteria as laid down in specifications

D. All of the above
7065. In transformers using hot rolled steel, the cross-section of the yoke is made about __________ greater than that of the core?
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A. 5 percent

B. 30 percent

C. 15 percent

D. 10 percent

E. none of the above

7066. Power transformers have rating_______________?
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A. none of the above

B. equal to 100 kVA

C. equal to 50 kVA

D. above 200 kVA
7067. In induction motors, the length of air gap in kept as small as mechanically possible is order to have____________?
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A. any of the above

B. high power factor

C. low power factor

D. high over load capacity

7068. ____________are used for construction of core of electromagnets?
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A. None of the above

B. Soft magnetic materials

C. Either A. or B.

D. Hard magnetic materials

7069. The density of hydrogen is __________ times the density of air?
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A. 2.5

B. 0.07

C. 3.5

D. 1.5

7070. Which of the following methods may be adopted to reduce the effects of armature reaction ?
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A. Increasing reluctance of pole tips

B. Increase in length of air gap at pole tips

C. All of the above

D. Interpoles

E. Compensating windings

7071. Power transformers should be designed to have maximum efficiency________________?
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A. any of the above

B. at or near full load

C. at one-half load

D. at one-fourth load

7072. The cylindrical windings using circular conductors are used for current rating of____________?
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A. upto 20 A

B. upto 80 A

C. upto 40 A

D. upto 60 A

7073. The forced oil and air circulation method is usual one for transformers of capacities____________?
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A. upto 5 MVA

B. upto 10 MVA

C. 30 MVA upwards

D. upto 20 MVA

7074. The change in flux linkages can be caused in which of the following ways ?
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A. The flux is constant with respect to time and is stationary and the coil moves through it

B. The coil is stationary with respect to flux and the flux varies in magnitude with respect to time

C. Both the changes mentioned above occur together, i.e., the coil moves through a time varying field

D. All of the above
7075. Hydrogen has a heat transfer co-efficient __________ times that of air?
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A. 3.5

B. 4.5

C. 2.5

D. 1.5
7076. ____________ is the common method of applying brushes to the commntator?
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A. Reaction

B. Trailing

C. Radial

D. All of the above
7077. In direct cooled system using hydrogen both stator and rotor conductors are made____________?
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A. solid

B. hollow

C. perforated

D. any ofthe above

7078. Multi-layer helical windings are commonly used in the transformers as high voltage windings_______________?
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A. upto 80 kV

B. upto 20 kV

C. upto 50 kV

D. for 110 kV and above
7079. The mcrease in heat dissipation by air blasts is due to increase in______________?
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A. any ofthe above

B. convection

C. conduction

D. radiation

7080. The heated parts of an electrical machine dissipate heat into their surroundings by which of the following modes of heat dissipation ?
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A. Conduction

B. All of the above

C. Radiation

D. Convection

7081. electromagnets generally function as holding magnets ?
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A. None of the above

B. Portative

C. Either of the above

D. Tractive

7082. The design of mechanical parts is particularly important in case of __________ speed machines?
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A. any of the above

B. high

C. medium

D. low

7083. Multiple inlet system of air cooling of turbo-alternators can be used for machines of rating upto_______________?
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A. 60 MW

B. 10 MW

C. 150 MW

D. 30 MW

7084. cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall______________?
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A. Indirect

B. Any of the above

C. Direct

D. Conventional

7085. ___________ brushes are fragile and cause excessive wear of commutator?
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A. Electro graphitic

B. Hard carbon

C. Natural graphite

D. Metal graphite

7086. D.C. servomotors are used in______________?
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A. purely D.C. control systems

B. purely AC. control systems

C. both D.C. and AC. control systems

D. none of the above

7087. In self cooled motors the cooling time constant is about ___________ than the heating time constant because cooling conditions are worse at standstill?
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A. 4 to 5 times greater

B. none of the above

C. 3 to 4 times greater

D. 2 to 3 times greater
7088. The efficiency of a machine should be as ____________ as possible to reduce the operating cost?
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A. high

B. none of the above

C. either of the above

D. low

7089. Aluminium when adopted as a conductor material in __________ transformers, decreases the overall cost of the transformer?
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A. large size

B. any of the above size

C. medium size

D. small size
7090. For large power transformers, self oil cooled type or air blast type which of the following values of current density may be used?
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A. 2.2 to 3.2 A/mm2

B. 1.5 to 2.0 A/mm2

C. 3.2 to 4.2 A/mm2

D. 1.0 to 1.2 A/mm2

7091. Dummy coil should not be used in_________________?
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A. small machines

B. none of the above

C. large machines

D. either A. or B.

7092. The usual values of maximum flux densities for distribution transformers using hot rolled silicon steel are______________?
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A. 0.8 to 1.0 Wb/m2

B. 0.5 to 0.8 Wb/m2

C. 1.4 to 1.8 Wb/m2

D. 1.1 to 1.35 Wb/m2
7093. Which of the following is the major consideration to evolve a good design ?
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A. Durability

B. All of the above

C. Compliance with performance criteria as laid down in specifications

D. Cost

7094. The thermal conductivity of hydrogen is _____________ times that of air?
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A. 5

B. 7

C. 2

D. 3

7095. Which of the following materials is used in the manufacture of resistance grids to be used in the starters of large motors ?
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A. Aluminium

B. Cast-iron

C. Copper

D. Steel

7096. _______________is universally used for windings of electrical machines because it is easily workable without any possibility of fracture?
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A. Aluminium

B. Silver

C. Steel

D. Copper
7097. In a D.C. machine, the value of peripheral speed should not, normally, exceed___________?
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A. 10 m/s

B. 20 m/s

C. 40 m/s

D. 30 m/s
7098. Which of the following is an advantage of hydrogen cooling ?
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A. Smaller size of coolers

B. Increase in efficiency

C. Increase in life

D. All of the above

E. Increase in ratings

7099. For a cell to work, which of the following condition(s) become necessary ___________?
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A. Two electrodes of different metas should be inserted in the electrolyte, not touching each other

B. All above three conditions are necessary

C. Electrolyte must chemically react with one of the electrodes

D. Electrolyte liquid or paste should be conducting

7100. Cell short circuit results in_________?
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A. reduced gassing on charge

B. abnormal high temperature

C. low sp. gravity electrolyte

D. all above