electrical engineering MCQs – Page 331

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 Review each marked answer and report any item that may be outdated or unclear.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 generation 2. analog electronics 3. solid state switching circuits 4. parallel circuits 5. switchgear and protection 6. op amp circuits 7. transistor audio power amplifiers 8. electrostatics 9. heating and welding 10. multi stage transistor amplifiers 11. passive filters 12. network theorems 13. regulated d c power supply 14. a c fundamentals circuits and circuit theory 15. electromagnetic induction 16. power electronics 17. magnetism and electromagnetism 18. transformers 19. modulation and demodulation 20. d c generators 21. semiconductor theory 22. single phase induction motors 23. semiconductor diode 24. hybrid parameters 25. digital electronics 26. oscillators 27. earthing or grounding 28. single stage transistor amplifiers 29. d c motors 30. transistor biasing 31. amplifiers with negative feedback 32. basic electrical 33. electronic instruments 34. synchronous motors 35. field effect transistors fet 36. magnetic circuit 37. control systems 38. industrial drives 39. power generation 40. series parallel circuits 41. transistor tuned amplifiers 42. electrical engineering materials 43. rectifiers and converters 44. integrated circuits 45. scr silicon controlled rectifiers 46. cables 47. polyphase induction motors 48. measurement and instrumentation 49. transistors 50. electrical machine design 51. electrolysis and storage of batteries 52. electric traction 53. transmission and distribution

6601. A rotary converter operates at a______________?
0

A. high power factor

B. low power factor

C. none of the above

D. zero power factor

6602. Which of the following AC. motors is usually used in large motor-generator sets?
0

A. Squirrel cage induction motor

B. Any of the above

C. Slip ring induction motor

D. Synchronous motor

6603. The efficiency of an electrolytic rectifier is nearly____________?
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A. 70%

B. 80%

C. 40%

D. 60%

6604. Mercury, in arc rectifiers, is chosen for cathode because________________?
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A. all of the above

B. its ionization potential is relatively low

C. it remains in liquid state at ordinary temperature

D. its atomic weight is quite high

E. its boiling point and specific heat are low

6605. A mercury arc rectifier possesses __________ regulation characteristics
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A. curved line

B. exponential

C. none of the above

D. straight line

6606. In a mercury pool rectifier, the voltage drop across its electrodes___________?
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A. is almost independent of load current

B. varies exponentially with the load current

C. is directly proportional to load

D. is inversely proportional to load

6607. In a grid control of mercury arc rectifiers when the grid is made positive relative to cathode, then it the electrons on their may to anode.
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A. decelerates

B. any of the above

C. none of the above

D. accelerates

6608. Which of the following rectifiers are primarily used for charging of low voltage batteries from AC supply ?
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A. Selenium rectifiers

B. Copper oxide rectifiers

C. Electrolytic rectifiers

D. Mercury arc rectifiers

E. Mechanical rectifiers

6609. It is the_________of the transformer on which the magnitude of angle of overlap depends?
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A. leakage reactance

B. resistance

C. capacitance

D. any of the above

6610. Ageing of a selenium rectifier may change the output voltage by__________?
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A. 5 to 10 per cent

B. none of the above

C. 15 to 20 per cent

D. 25 to 30 per cent

6611. The internal efficiency of a mercury arc rectifier depends on___________?
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A. voltage only

B. current only

C. none of the above

D. voltage and current

E. r.m.s. value of current

6612. Which of the following is the loss within the mercury arc rectifier chamber ?
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A. Voltage drop at the cathode

B. Voltage drop at the anode

C. Voltage drop in arc

D. All of the above

6613. If cathode and anode connections in a mercury arc rectifier are inter changed_____________?
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A. the rectifier will not operate

B. internal losses will be reduced

C. both ion and electron streams will move in the same direction

D. the rectifier will operate at reduced efficiency

6614. In a single phase rotary converter the number of slip rings will be_____________?
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A. three

B. none

C. two

D. four

E. six

6615. A rotary converter combines the function of____________?
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A. none of the above

B. a D.C. series motor and a D.C. generator

C. an induction motor and a D.C. generator

D. a synchronous motor and a D.C. generator

6616. Which of the following rectifiers have been used extensively in supplying direct current for electroplating ?
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A. Copper oxide rectifiers

B. None of the above

C. Mercury arc rectifiers

D. Mechanical rectifiers

E. Selenium rectifiers

6617. Glass rectifiers are usually made into units capable of D.C. output (maximum continuous rating) of _____________?
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A. 400 A at 400 V

B. 500 A at 500 V

C. 200 A at 200 V

D. 100 A at 100 V

E. 300 A at 300 V

6618. In a three-phase mercury arc rectifiers each anode conducts for____________?
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A. one-half a cycle

B. one-fourth of a cycle

C. one-third of a cycle

D. two-third of a cycle

6619. Normally, which of the following is used, when a large-scale conversion from AC. to D.C. power is required ?
0

A. Mercury arc rectifier

B. Motor converter

C. Rotary converter

D. Motor-generator set

6620. The cathdde voltage drop, in a mercury arc rectifier, is due to_____________?
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A. expenditure of energy in ionization

B. expenditure of energy in overcoming the electrostatic field

C. surface resistance

D. expenditure of energy in liberating electrons from the mercury

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