MCQOPTIONS
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MCQOPTIONS
This section includes 76 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A rotary converter combines the function of |
| A. | an induction motor and a D.C. generator |
| B. | a synchronous motor and a D.C. generator |
| C. | a D. |
| D. | none of the above |
| Answer» C. a D. | |
| 2. |
The efficiency of the copper oxide rectifier seldom exceeds |
| A. | 90 to 95% |
| B. | 85 to 90% |
| C. | 80 to 85% |
| D. | 65 to 75% |
| Answer» E. | |
| 3. |
Which of the following rectifiers are primarily used for charging of low voltage batteries from AC. supply? |
| A. | Mechanical rectifiers |
| B. | Copper oxide rectifiers |
| C. | Selenium rectifiers |
| D. | Electrolytic rectifiers |
| Answer» E. | |
| 4. |
In a rotary converter I2R losses as compared to a D.C. generator of the same size will be |
| A. | same |
| B. | less |
| C. | double |
| D. | three times |
| Answer» C. double | |
| 5. |
Which of the following mercury arc rectifier will deliver least undulating current? |
| A. | Six-phase |
| B. | Three-phase |
| C. | Two-phase |
| D. | Single-phase |
| Answer» B. Three-phase | |
| 6. |
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. |
| A. | accelerates |
| B. | decelerates |
| C. | any of the above |
| D. | none of the above |
| Answer» B. decelerates | |
| 7. |
A rotary converter is a single machine with |
| A. | one armature and one field |
| B. | two armatures and one field |
| C. | one armature and two fields |
| D. | none of the above |
| Answer» B. two armatures and one field | |
| 8. |
The efficiency of an electrolytic rectifier is nearly |
| A. | 80% |
| B. | 70% |
| C. | 60% |
| D. | 40% |
| Answer» D. 40% | |
| 9. |
A rotary converter operates at a |
| A. | low power factor |
| B. | high power factor |
| C. | zero power factor |
| D. | none of the above |
| Answer» C. zero power factor | |
| 10. |
Which of the following is reversible in action? |
| A. | Motor generator set |
| B. | Motor converter |
| C. | Rotary converter |
| D. | Any of the above |
| E. | None of the above |
| Answer» D. Any of the above | |
| 11. |
Selenium rectifier can be operated at temperatures as high as |
| A. | 25°C |
| B. | 40°C |
| C. | 60°C |
| D. | 75°C |
| Answer» E. | |
| 12. |
Which of the following is the loss within the mercury arc rectifier chamber? |
| A. | Voltage drop in arc |
| B. | Voltage drop at the anode |
| C. | Voltage drop at the cathode |
| D. | All of the above |
| Answer» E. | |
| 13. |
Normally, which of the following is used, when a large-scale conversion from AC. to D.C. power is required? |
| A. | Motor-generator set |
| B. | Motor converter |
| C. | Rotary converter |
| D. | Mercury arc rectifier |
| Answer» E. | |
| 14. |
It is the_______of the transformer on which the magnitude of angle of overlap depends. |
| A. | resistance |
| B. | capacitance |
| C. | leakage reactance |
| D. | any of the above |
| Answer» D. any of the above | |
| 15. |
Mercury, in arc rectifiers, is chosen for cathode because |
| A. | Its ionization potential is relatively low |
| B. | Its atomic weight is quite high |
| C. | Its boiling point and specific heat are low |
| D. | All of the above |
| Answer» E. | |
| 16. |
A rotary converter operates at a%! |
| A. | low power factor |
| B. | high power factor |
| C. | zero power factor |
| D. | none of the above |
| Answer» C. zero power factor | |
| 17. |
Which of the following is reversible in action?%! |
| A. | Motor generator set |
| B. | Motor converter |
| C. | Rotary converter |
| D. | Any of the above |
| E. | None of the above |
| Answer» D. Any of the above | |
| 18. |
Selenium rectifier can be operated at temperatures as high as%! |
| A. | 25°C |
| B. | 40°C |
| C. | 60°C |
| D. | 75°C |
| Answer» E. | |
| 19. |
Which of the following is the loss within the mercury arc rectifier chamber?%! |
| A. | Voltage drop in arc |
| B. | Voltage drop at the anode |
| C. | Voltage drop at the cathode |
| D. | All of the above |
| Answer» E. | |
| 20. |
*$_Which of the following is the loss within the mercury arc rectifier chamber?? |
| A. | Voltage drop in arc |
| B. | Voltage drop at the anode |
| C. | Voltage drop at the cathode |
| D. | All of the above |
| Answer» E. | |
| 21. |
*$_Which of the following mercury arc rectifier will deliver least undulating current?? |
| A. | Six-phase |
| B. | Three-phase |
| C. | Two-phase |
| D. | Single-phase |
| Answer» B. Three-phase | |
| 22. |
*$_A rotary converter combines the function of? |
| A. | an induction motor and a D.C. generator |
| B. | a synchronous motor and a D.C. generator |
| C. | a D. |
| D. | none of the above |
| Answer» C. a D. | |
| 23. |
*/*_Normally, which of the following is used, when a large-scale conversion from AC. to D.C. power is required?? |
| A. | Motor-generator set |
| B. | Motor converter |
| C. | Rotary converter |
| D. | Mercury arc rectifier |
| Answer» E. | |
| 24. |
%_Normally, which of the following is used, when a large-scale conversion from AC. to D.C. power is required?_% |
| A. | Motor-generator set |
| B. | Motor converter |
| C. | Rotary converter |
| D. | Mercury arc rectifier |
| Answer» E. | |
| 25. |
_ In a grid control of mercury arc rectifiers when the grid is made positive relative to cathode, then it the electrons on their may to anode.$? |
| A. | accelerates |
| B. | decelerates |
| C. | any of the above |
| D. | none of the above |
| Answer» B. decelerates | |
| 26. |
_ The efficiency of the copper oxide rectifier seldom exceeds$? |
| A. | 90 to 95% |
| B. | 85 to 90% |
| C. | 80 to 85% |
| D. | 65 to 75% |
| Answer» E. | |
| 27. |
__It is the_______of the transformer on which the magnitude of angle of overlap depends.__ |
| A. | resistance |
| B. | capacitance |
| C. | leakage reactance |
| D. | any of the above |
| Answer» D. any of the above | |
| 28. |
_A rotary converter is a single machine with$? |
| A. | one armature and one field |
| B. | two armatures and one field |
| C. | one armature and two fields |
| D. | none of the above |
| Answer» B. two armatures and one field | |
| 29. |
_Which of the following rectifiers are primarily used for charging of low voltage batteries from AC. supply?$? |
| A. | Mechanical rectifiers |
| B. | Copper oxide rectifiers |
| C. | Selenium rectifiers |
| D. | Electrolytic rectifiers |
| Answer» E. | |
| 30. |
Mercury, in arc rectifiers, is chosen for cathode because$? |
| A. | Its ionization potential is relatively low |
| B. | Its atomic weight is quite high |
| C. | Its boiling point and specific heat are low |
| D. | All of the above |
| Answer» E. | |
| 31. |
Mercury, in arc rectifiers, is chosen for cathode because? |
| A. | Its ionization potential is relatively low |
| B. | Its atomic weight is quite high |
| C. | Its boiling point and specific heat are low |
| D. | All of the above |
| Answer» E. | |
| 32. |
The efficiency of an electrolytic rectifier is nearly? |
| A. | 80% |
| B. | 70% |
| C. | 60% |
| D. | 40% |
| Answer» D. 40% | |
| 33. |
In a rotary converter I2R losses as compared to a D.C. generator of the same size will be? |
| A. | same |
| B. | less |
| C. | double |
| D. | three times |
| Answer» C. double | |
| 34. |
In which of the following equipment direct current is needed? |
| A. | Telephones |
| B. | Relays |
| C. | Time switches |
| D. | All of the above |
| Answer» E. | |
| 35. |
The voltage drop at anode, in a mercury arc rectifier is due to |
| A. | self restoring property of mercury |
| B. | high ionization potential |
| C. | energy spent in overcoming the electrostatic field |
| D. | high temperature inside the rectifier |
| Answer» D. high temperature inside the rectifier | |
| 36. |
Ageing of a selenium rectifier may change the output voltage by |
| A. | 5 to 10 per cent |
| B. | 15 to 20 per cent |
| C. | 25 to 30 per cent |
| D. | none of the above |
| Answer» B. 15 to 20 per cent | |
| 37. |
In a three-phase mercury arc rectifiers each anode conducts for |
| A. | One-third of a cycle |
| B. | One-fourth of a cycle |
| C. | One-half a cycle |
| D. | Two-third of a cycle |
| Answer» B. One-fourth of a cycle | |
| 38. |
A commutating rectifier consists of commutator driven by |
| A. | An induction motor |
| B. | A synchronous motor |
| C. | A D.C. series motor |
| D. | A D.C. shunt motor |
| Answer» C. A D.C. series motor | |
| 39. |
In a mercury arc rectifier characteristic blue luminosity is due to |
| A. | colour of mercury |
| B. | ionization |
| C. | high temperature |
| D. | electron streams |
| Answer» C. high temperature | |
| 40. |
In a mercury arc rectifier______ flow from anode to cathode |
| A. | ions |
| B. | electrons |
| C. | ions and electrons |
| D. | any of the above |
| Answer» B. electrons | |
| 41. |
The ionization potential of mercury is approximately |
| A. | 5.4 V |
| B. | 8.4 V |
| C. | 10.4 V |
| D. | 16.4 V |
| Answer» D. 16.4 V | |
| 42. |
Which of the following rectifiers have been used extensively in supplying direct current for electroplating? |
| A. | Copper oxide rectifiers |
| B. | Selenium rectifiers |
| C. | Mercury arc rectifiers |
| D. | Mechanical rectifiers |
| E. | None of the above |
| Answer» C. Mercury arc rectifiers | |
| 43. |
With a motor converter it is possible to obtain D.C. voltage only upto |
| A. | 200-100 V |
| B. | 600-800 V |
| C. | 1000-1200 V |
| D. | 1700-2000 V |
| Answer» E. | |
| 44. |
The metal rectifiers are preferred to valve rectifiers due to which of the following advantages ? |
| 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 |
| Answer» D. None of the above | |
| 45. |
In a rotary converter armature currents are |
| A. | d.c. only |
| B. | a.c. only |
| C. | partly a.c. and partly d.c. |
| D. | none of the above |
| Answer» D. none of the above | |
| 46. |
A mercury arc rectifier possesses ________ regulation characteristics |
| A. | straight line |
| B. | curved line |
| C. | exponential |
| D. | none of the above |
| Answer» E. | |
| 47. |
In a single phase rotary converter the number of slip rings will be |
| A. | two |
| B. | three |
| C. | four |
| D. | six |
| Answer» B. three | |
| 48. |
On which of the following factors the number of phases for which a rectifier should be designed depends? |
| A. | The voltage regulation of the rectifier should be low |
| B. | In the output circuit there should be no harmonics |
| C. | The power factor of the system should be high |
| D. | All of the above |
| Answer» E. | |
| 49. |
The applications of selenium rectifiers are usually limited to potential of |
| A. | 10 V |
| B. | 30 V |
| C. | 60 V |
| D. | 100 V |
| E. | 200 V |
| Answer» E. 200 V | |
| 50. |
The cathdde voltage drop, in a mercury arc rectifier, is due to |
| A. | expenditure of energy in ionization |
| B. | surface resistance |
| C. | expenditure of energy in overcoming the electrostatic field |
| D. | expenditure of energy in liberating electrons from the mercury |
| Answer» E. | |