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
6601. A rotary converter operates at a______________?
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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?
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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 ?
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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
6621. Which of the following are the applications of D.C. system ?
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A. Arc lamps for search lights

B. Arc welding

C. Electrolytic and electro-chemical processes

D. All of the above

E. Battery charging work

6622. The advantage of mercury arc rectifier is that________________?
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A. it is comparatively noiseless

B. it is light in weight and occupies small floor space

C. it has high efficiency

D. it has high overload capacity

E. all of the above
6623. In which of the following equipment direct current is needed ?
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A. Relays

B. All of the above

C. Telephones

D. Time switches

6624. On which of the following factors the number of phases for which a rectifier should be designed depend ?
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A. In the output circuit there should be no harmonics

B. all of the above

C. The voltage regulation of the rectifier should be low

D. The power factor of the system should be high

E. The rectifier supply transformer should be utilized to the best ad-vantage

6625. Which of the following statement is incorrect ?
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A. Copper oxide rectifier is not stable during early life

B. Copper oxide rectifier is not a perfect rectifier

C. Copper oxide rectifier finds use in control circuits

D. Copper oxide rectifier has a low efficiency

E. Copper oxide rectifier is a linear device
6626. In a rotary converter armature currents are______________?
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A. a.c. only

B. d.c. only

C. partly a.c. and partly d.c.
6627. When a rectifier is loaded which of the following voltage drops take place ?
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A. Arc voltage drop

B. All of the above

C. Voltage drop in resistance of transformer and smoothing chokes

D. Voltage drop in transformer reactance

6628. In a mercury arc rectifier positive ions are attracted towards______________?
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A. mercury pool

B. shell bottom

C. anode

D. cathode
6629. The voltage drop at anode, in a mercury arc rectifier is due to_____________?
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A. high ionization potential

B. self restoring property of mercury

C. energy spent in overcoming the electrostatic field

D. high temperature inside the rectifier

6630. Which of the following methods may be used to convert A.C. system to D.C ?
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A. Motor-generator sets

B. Rotary converters

C. All of the above

D. Rectifiers

E. Motor converters

6631. Which of the following is reversible in action ?
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A. Rotary converter

B. Any of the above

C. None of the above

D. Motor generator set

E. Motor converter

6632. A synchronous converter can be started______________?
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A. from AC. side as induction motor

B. from D.C. side as D.C. motor

C. by means of a small auxiliary motor

D. any of the above methods

E. none of the above methods

6633. A rotary converter is a single machine with______________?
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A. one armature and one field

B. two armatures and one field

C. one armature and two fields

D. none of the above

6634. In phase-shift control method the control is carried out by varying the of grid voltage
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A. none of the above

B. phase

C. any of the above

D. magnitude

E. polarity

6635. The potential drop in the arc, in a mercury arc rectifier, varies_____________?
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A. 0.05 V to 0.2 V per cm length of the arc

B. 2 V to 3.5 V per cm length of the arc

C. none of the above

D. 0.5 V to 1.5 V per cm length of the arc

6636. The ignited or auxiliary anode in mercury arc rectifier is made of____________?
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A. aluminium

B. copper

C. graphite

D. boron carbide
6637. Which of the following mercury arc rectifier will deliver least undulating current?
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A. Three-phase

B. Two-phase

C. Six-phase

D. Single-phase

6638. The metal rectifiers are preferred to valve rectifiers due to which of the following advantages ?
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A. They are mechanically strong

B. They do not require any voltage for filament heating

C. Both (A) and (B)

D. None of the above

6639. In selenium rectifiers efficiencies ranging from _______ to _______ percent are attainable?
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A. 25, 35

B. 40, 50

C. 60, 70

D. 75, 85
6640. The voltage drop between the anode and cathode, of a mercury arc rectifier comprises of the following_____________?
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A. anode drop, cathode drop and arc drop

B. anode drop and cathode drop

C. anode drop and arc drop

D. cathode drop and arc drop

6641. Copper oxide rectifier is usually designed not to operate above___________?
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A. 20C

B. 30C

C. 10C

D. 45C
6642. Which of the following metals is generally manufactured by electrolysis process ?
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A. Copper

B. Zinc

C. Aluminium

D. None of the above

E. Load

6643. In a phase-shift control method, the phase shift between anode and grid voltages can be achieved by means of______________?
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A. synchronous generator

B. induction regulator

C. synchronous motor

D. shunt motor

6644. An audio amplifier is an example of _________________?
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A. Digital IC

B. Linear IC

C. Both digital and linear IC

D. None of the above

6645. ICs are generally made of ________________?
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A. Copper

B. None of the above

C. Silicon

D. Germanium

6646. We use _____________ ICs in computers?
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A. Digital

B. Linear

C. Both digital and linear

D. None of the above

6647. Which of the following is most difficult to fabricate in an IC ?
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A. Capacitor

B. Transistor

C. Diode

D. FET

6648. _________________cannot be fabricated on an IC?
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A. Large inductors and transformers

B. Transistors

C. Resistors

D. Diodes

6649. The SiO2 layer in an IC acts as ________________?
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A. Mechanical output

B. An insulating layer

C. None of the above

D. A resistor

6650. An IC has _______________size?
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A. Very large

B. Extremely small

C. Large

D. None of the above