electrical engineering MCQs – Page 330

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 Review each marked answer and report any item that may be outdated or unclear.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
6581. For germanium the forbidden energy gap is_______________?
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A. 0.15 eV

B. 0.7eV

C. 0.25 eV

D. 0.5eV

6582. The metal having the lowest temperature coefficient of resistance is_________________?
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A. aluminium

B. gold

C. copper

D. kanthal

6583. Carbon rods are used in wet and dry cells because_____________?
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A. carbon rod serves as conductor

B. carbon can resist the attack of battery acid

C. both (A) and (B)

D. either (A) or (B)

6584. Carbon electrodes are not used in_______________?
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A. electric arc furnace

B. GLS lamps

C. dry cells

D. cinema projectors

6585. Which of the following materials is the best conductor of electricity ?
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A. Carbon

B. Copper

C. Tungsten

D. Aluminium

6586. In a rotary converter I2R losses as compared to a D.C. generator of the same size will be___________?
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A. three times

B. less

C. double

D. same

6587. In a mercury arc rectifier characteristic blue luminosity is due to_____________?
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A. electron streams

B. high temperature

C. colour of mercury

D. ionization
6588. Selenium rectifier can be operated at temperatures as high as____________?
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A. 25C

B. 60C

C. 75C

D. 40C

6589. In a mercury arc rectifier, the anode is usually made of_____________?
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A. copper

B. tungsten

C. aluminium

D. graphite

E. silver

6590. A commutating rectifier consists of commutator driven by___________?
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A. a D.C. series motor

B. a synchronous motor

C. an induction motor

D. a D.C. shunt motor

6591. A rotary converter in general construction and design, is more or less like___________?
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A. an alternator

B. any D.C. machine

C. a transformer

D. an induction motor

6592. In which of the following appUcations, direct current is absolutely essential ?
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A. Variable speed operation

B. Electrolysis

C. Illumination

D. Traction

6593. In a mercury arc rectifier________ flow from anode to cathode
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A. ions

B. any of the above

C. ions and electrons

D. electrons

6594. The ionization potential of mercury is approximately_____________?
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A. 5.4 V

B. 10.4 V

C. 16.4 V

D. 8.4 V

6595. In mercury arc rectifiers having grid, the arc can be struck between anode and cathode only when the grid attains a certain potential, this potential being known as______________?
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A. maximum grid voltage

B. critical grid voltage

C. none of the above

D. any of the above

6596. The efficiency of the copper oxide rectifier seldom exceeds____________?
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A. 80 to 85%

B. 90 to 95%

C. 85 to 90%

D. 65 to 75%
6597. To produce cathode spot in a mercury arc rectifier______________?
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A. low mercury vapour pressures are used

B. anode is heated

C. an auxiliary electrode is used

D. tube is evacuated

6598. In a glass bulb mercury arc rectifier the maximum current rating is restricted to___________?
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A. 1500 A

B. 500 A

C. 2000 A

D. 1000 A

6599. The applications of selenium rectifiers are usually limited to potential of_____________?
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A. 200 V

B. 10 V

C. 30 V

D. 100 V

E. 60 V

6600. With a motor converter it is possible to obtain D.C. voltage only upto__________?
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A. 200-100 V

B. 10001200 V

C. 17002000 V

D. 600800 V