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
6801. Which of the following methods is easily applicable to control the speed of the squirrel-cage induction motor _____________?
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A. By injecting e.m.f. in the rotor circuit

B. Rotor rheostat control

C. By changing the number of stator poles

D. By operating two motors in cascade

6802. 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. absent

B. large

C. small

D. infinity

6803. The shape of the torque/slip curve of induction motor is__________?
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A. rectangular parabola

B. straigth line

C. parabola

D. hyperbola

6804. The starting torque of a 3-phase squirrel cage induction motor is____________?
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A. twice the full load torque

B. 1.5 times the full load torque

C. equal to full load torque

6805. 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

6806. 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. smaller

C. bigger

D. same

6807. A 3-phase slip ring motor has____________?
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A. double cage rotor

B. wound rotor

C. any of the above

D. short-circuited rotor

6808. Short-circuit test on an induction motor cannot be used to determine___________?
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A. copper losses

B. transformation ratio

C. windage losses

D. power scale of circle diagram

6809. In a squirrel cage motor the induced e.m.f. is___________?
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A. dependent on the shaft loading

B. dependent on the number of slots

C. slip times the stand still e.m.f. induced in the rotor

D. none of the above

6810. Which motor is preferred for use in mines where explosive gases exist ?
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A. Induction motor

B. Air motor

C. Synchronous motor

D. D.C. shunt motor

6811. The speed of a squirrel-cage induction motor can be controlled by all of the following except_____________?
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A. changing winding resistance

B. changing number of poles

C. reducing supply voltage

D. changing supply frequency

6812. 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, no-load test and stator resistance test

B. Block rotor test and no-load test

C. Block rotor test only

D. No load test only

6813. The circle diagram for an induction motor cannot be used to determine____________?
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A. efficiency

B. power factor

C. output

D. frequency

6814. 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

6815. The efficiency of an induction motor can be expected to be nearly____________?
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A. 80 to 90%

B. 60 to 90%

C. 99%

D. 95 to 98%

6816. Insertion of reactance in the rotor circuit_______?
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A. increases starting torque but maxi-mum torque decreases

B. increases starting torque as well as maximum torque

C. reduces starting torque as well as maximum torque

D. increases starting torque but maxi-mum torque remains unchanged

6817. The torque of an induction motor is___________?
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A. proportional to the square of the slip

B. directly proportional to slip

C. inversely proportional to slip

D. none of the above

6818. The frame of an induction motor is usually made of____________?
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A. cast iron

B. aluminium

C. silicon steel

D. bronze

6819. The cogging of an induction motor can be avoided by____________?
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A. auto-transformer starter

B. having number of rotor slots more or less than the number of stator slots (not equal)

C. using DOL starter

D. proper ventilation

6820. The torque developed by a 3-phase induction motor least depends on__________?
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A. shaft diameter

B. rotor power factor

C. rotor current

D. rotor e.m.f.

6821. If a 3-phase supply is given to the stator and rotor is short circuited rotor will move___________?
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A. in the opposite direction as the direction of the rotating field

B. in any direction depending upon phase squence of supply

C. in the same direction as the direction of the field
6822. In a three-phase induction motor_______________?
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A. iron losses in motor will be negligible as compared to that in rotor

B. iron losses in stator will be more than that in rotor

C. iron losses in stator will be negligible as compared to that in rotor

D. iron losses in stator will be less than that in rotor

6823. In squirrel cage induction motors, the rotor slots are usually given slight skew in order to__________?
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A. reduce magnetic hum

B. reduce eddy currents

C. reduce accumulation of dirt and dust

D. reduce windage losses

6824. 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
6825. 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. locking of rotor due to harmonics

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

6826. 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 torque produced will be very large

B. The slip of the motor will be 5%

C. The rotor will run at very high speed

D. The rotor will not run
6827. The torque of a rotor in an induction motor under running condition is maximum__________?
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A. at the unit value of slip

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

C. at the value of the slip which makes rotor reactance per phase equal to the resistance per phase

D. at the zero value of slip

6828. In case the air gap in an induction motor is increased?
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A. the magnetising current of the rotor will decrease

B. the power factor will decrease

C. speed of motor will increase

D. the windage losses will increase

6829. Lubricant used for ball bearing is usually___________?
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A. graphite

B. mineral oil

C. grease

D. molasses

6830. 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
6831. In three-phase squirrel-cage induction motors____________?
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A. rotor conductors are connected to insulation

B. rotor conductors are kept open

C. rotor conductors are short-circuited through end rings

D. rotor conductor ends are short-circuited through slip rings

6832. Slip ring motor is recommended where____________?
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A. frequent starting, stopping and reversing is required

B. high starting torque is needed

C. speed control is required

D. all above features are required
6833. Which type of bearing is provided in small induction motors to support the rotor shaft ?
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A. Ball bearings

B. Cast iron bearings

C. None of the above

D. Bush bearings

6834. Less maintenance troubles are experienced in case of___________?
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A. slip ring induction motor

B. squirrel cage induction motor

C. both A. and (b)

D. none of the above

6835. In the circle diagram for induction motor, the diameter of the circle represents____________?
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A. rotor current

B. running torque

C. line voltage

D. slip

6836. In medium sized induction motors, the slip is generally around___________?
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A. 0.04%

B. 4%

C. 0.40%

D. 14%

6837. An induction motor is identical to_________?
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A. synchronous motor

B. D.C. compound motor

C. D.C. series motor

D. asynchronous motor
6838. An induction motor with 1000 r.p.m. speed will have____________?
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A. 2 poles

B. 6 poles

C. 8 poles

D. 4 poles

6839. The power factor of an induction motor under no-load conditions will be closer to_____________?
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A. 0.2 lagging

B. 0.5 leading

C. unity

D. 0.2 leading

6840. Star-delta starting of motors is not possible in case of____________?
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A. single phase motors

B. high speed motors

C. low horse power motors

D. variable speed motors

6841. The complete circle diagram of induetion motor can be drawn with the help of data found from__________?
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A. stator resistance test

B. noload test

C. all of the above

D. blocked rotor test

6842. Wattmeter cannot be designed on the principle of_________________?
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A. moving iron instrument

B. thermocouple instrument

C. electrostatic instrument

D. electrodynamic instrument

6843. A moving-coil permanent-magnet instrument can be used as ____________by using a low resistance shunt?
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A. voltmeter

B. ammeter

C. flux-meter

D. ballistic galvanometer

6844. The desirable static characteristics of a measuring system are______________?
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A. accuracy and reproducibility

B. accuracy, sensitivity and reproducibility

C. static error

D. drift and dead zone

6845. If an instrument has cramped scale for larger values, then it follows________________?
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A. none of the above

B. logarithmic law

C. square law

D. uniform law

6846. A multirangq instrument has________________?
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A. variable turns of coil

B. any of the above

C. multicoii arrangement

D. multiple shunt or series resistances inside the meter

E. multi range meters inside the measurement system

6847. Commonly used standard capacitor is______________?
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A. concentric cylindrical type

B. electrostatic type

C. multilayer parallel plate type

D. spherical type

6848. A phase shifting transformer is used in conjunction with_______________?
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A. Crompton potentiometer

B. D.C. potentiometer

C. A.C. co-ordinate potentiometer

D. Drysdale potentiometer
6849. A moving-coil permanent-magnet instrument can be used as flux-meter_____________?
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A. by eliminating the control springs

B. by making control springs of large moment of inertia

C. by using a low resistance shunt

D. by using a high series resistance

6850. The ratio of maximum displacement deviation to full scale deviation of the instrument is called_______________?
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A. linearity

B. dynamic deviation

C. static sensitivity

D. precision or accuracy