electrical engineering MCQs – Page 42

Practise multiple-choice questions from electrical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

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
821. Which of the following load normally needs starting torque more than the rated torque?
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A. Centrifugal pumps

B. Air compressors

C. Conveyors

D. Blowers

822. The hysteresis loss in a D.C. machine least depends on____________?
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A. Frequency of magnetic reversals

B. Rate of flow of ventilating air

C. Maximum value of flux density

D. Volume and grade of iron

823. The terminal voltage of a D.C. shunt generator drops on load because of all of the following reasons except:_____________?
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A. field weakening due to armature reaction and armature

B. armature resistance drop

C. armature reaction

D. commutation
824. In D.C. shunt motors as load is reduced__________________?
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A. the speed will increase abruptly

B. the speed will remain almost/constant

C. the speed will reduce

D. the speed will increase in proportion to reduction in load

825. The rapid wear of brushes takes place due to____________?
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A. rough commutator bars

B. all of the above factors

C. excessive spring pressure

D. high mica insulation between com-mutation bars

E. abrasion from dust

826. In D.C. machines the residual magnetism is of the order of_________________?
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A. 20 to 25 per cent

B. 50 to 75 per cent

C. 10 to 15 per cent

D. 2 to 3 per cent
827. In Ward-Leonard control the lower limit of speed is imposed by________?
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A. core losses of motor

B. all of the above

C. residual magnetism of the generator

D. mechanical losses of motor and generator together

828. Which of the following motors is usually used in house-hold refrigerators ?
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A. D.C. series motor

B. Synchronous motor

C. D.C. shunt motor

D. Reluctance motor

E. Single phase induction motor (split phase start or induction run motor)
829. Open circuited armature coil of a D.C. machine is________________?
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A. identified by the scarring of the commutator segment to which open circuited coil is connected

B. indicated by a spark completely around the commutator

C. both A. and (b)

D. none of the above

830. In D.C. generators on no-load, the air gap flux distribution in space is______________?
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A. pulsating

B. triangular

C. sinusoidal

D. flat topped
831. The resistance of armature winding depends on
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A. all of the above

B. length of conductor

C. number of conductors

D. cross-sectional area of the conductor

832. Sparking at the commutator of a D.C. motor may result in____________?
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A. damage to commutator segments

B. damage to commutator insulation

C. increased power consumption

D. all of the above
833. The frame of an induction motor is usually made of____________?
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A. cast iron

B. bronze

C. silicon steel

D. aluminium

834. D.C. motor is to drive a load which has certain minimum value for most of the time and some peak value for short duration. We will select the________________?
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A. shunt motor

B. compound motor

C. series motor

D. any of the above

835. If the field of a D.C. shunt motor gets opened while motor is running______________?
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A. the motor will attain dangerously high speed 1

B. the speed of motor will be reduced %

C. the motor will continue to nuvat constant speed

D. the armature current will reduce

836. Armature reaction in a generator results in_____________?
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A. damagnetising the center of all poles

B. demagnetisation of trailing pole tip and magnetisation of leading pole tip

C. magnetising the center of all poles

D. demagnetisation of leading pole tip and magnetisation of trailing pole tip
837. In case-the conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be______________?
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A. 100%

B. less than 50%

C. anywhere between 75% and 90%

D. around 90%

838. The number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is______________?
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A. 6

B. 8

C. 2

D. 4
839. In a four-pole D.C. machine____________?
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A. all the four poles are south poles

B. alternate poles are north and south

C. two north poles follow two south poles

D. all the four poles are north poles

840. A 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be_____________?
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A. 220 V

B. about 50 V

C. about 2 V

D. zero