MCQOPTIONS
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MCQOPTIONS
This section includes 34 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. |
In the transformer the function of a conservator is to~! |
| A. | Provide fresh air for cooling the transformer |
| B. | Supply cooling oil to transformer in time of need |
| C. | Protect the transformer from damage when oil expends due to heating |
| D. | None of the above |
| Answer» D. None of the above | |
| 2. |
A three-phase ‚à Ü-connected generator is driving a balanced load such that each phase current is 12 A in magnitude. When I Œ∏a = 12 ‚à †30¬∞ A, what are the polar expressions for the other phase currents?~! |
| A. | I Œ∏b = 12 ‚à †150¬∞ A, I Œ∏c = 12 ‚à †-90¬∞ A |
| B. | I Œ∏b = 12 ‚à †120¬∞ A, I Œ∏c = 12 ‚à †30¬∞ A |
| C. | I Œ∏b = 12 ‚à †30¬∞ A, I Œ∏c = 12 ‚à †120¬∞ A |
| D. | I Œ∏b = 12‚à †90¬∞ A, I Œ∏c = 12 ‚à †90¬∞ A |
| Answer» B. I ≈í‚àèb = 12 ‚Äö√ ‚Ä 120¬¨‚àû A, I ≈í‚àèc = 12 ‚Äö√ ‚Ä 30¬¨‚àû A | |
| 3. |
A simple three-phase generator consists of three conductive loops separated by 120°.%! |
| A. | True |
| B. | False |
| Answer» B. False | |
| 4. |
A three-phase generator is connected to three 90 Ω load resistors. Each coil generates 120 V ac. A common neutral line exists. How much current flows through the common neutral line?%! |
| A. | 0 A |
| B. | 1.33 A |
| C. | 3.99 A |
| D. | 2.66 A |
| Answer» B. 1.33 A | |
| 5. |
The term 'squirrel-cage' applies to a type of three-phase ac generator.%! |
| A. | True |
| B. | False |
| Answer» B. False | |
| 6. |
A two-phase generator is connected to two 90 Ω load resistors. Each coil generates 120 V ac. A common neutral line exists. How much current flows through the common neutral line?%! |
| A. | 1.33 A |
| B. | 1.88 A |
| C. | 2.66 A |
| D. | 1.77 A |
| Answer» E. | |
| 7. |
A single-phase sinusoidal voltage of 120 V is connected to a 90 Ω load. Current in the circuit is%! |
| A. | 13.3 mA |
| B. | 133 mA |
| C. | 1.33 A |
| D. | 6.2 A |
| Answer» D. 6.2 A | |
| 8. |
Power is measured in a three-phase load by using an ammeter.%! |
| A. | True |
| B. | False |
| Answer» C. | |
| 9. |
A constant load power means a uniform conversion of%! |
| A. | Mechanical to electrical energy |
| B. | Electrical to mechanical energy |
| C. | Current to voltage |
| D. | Voltage to current |
| Answer» C. Current to voltage | |
| 10. |
In a Y-connected generator, there is a 120° difference between each line voltage and the nearest phase voltage.%! |
| A. | True |
| B. | False |
| Answer» C. | |
| 11. |
A balanced load is one in which all the impedances are equal.%! |
| A. | True |
| B. | False |
| Answer» B. False | |
| 12. |
In a ‚à Ü-connected generator, there is a 120¬∞ difference between each line current and the nearest phase current.%! |
| A. | True |
| B. | False |
| Answer» C. | |
| 13. |
An alternator is an electromechanical ac generator.%! |
| A. | True |
| B. | False |
| Answer» C. | |
| 14. |
Compare the total copper cross sections in terms of current-carrying capacity for a single-phase and a three-phase 120 V system with effective load resistance of 15 Ω.%! |
| A. | Single-phase 32 A; three-phase 16 A |
| B. | Single-phase 16 A; three-phase 8 A |
| C. | Single-phase 8 A; three-phase 4 A |
| D. | Single-phase 16 A; three-phase 0 A |
| Answer» C. Single-phase 8 A; three-phase 4 A | |
| 15. |
In a Y-connected circuit, between each line voltage and the nearest phase voltage, there is a phase angle of%! |
| A. | 0° |
| B. | 30° |
| C. | 60° |
| D. | 120° |
| Answer» C. 60¬¨‚àû | |
| 16. |
The stator is the rotating assembly in a generator or motor.%! |
| A. | True |
| B. | False |
| Answer» C. | |
| 17. |
In a Y-connected source feeding a ‚Äö√ √ú-connected load,%! |
| A. | Each phase of the load has one-third of the full line voltage across it |
| B. | Each phase of the load has two-thirds of the full line voltage across it |
| C. | Each phase of the load has the full line voltage across it |
| D. | Each phase of the load has a voltage across it equal to ‚à ö3 |
| Answer» D. Each phase of the load has a voltage across it equal to ‚Äö√ √∂3 | |
| 18. |
In a balanced three-phase load, each phase has%! |
| A. | An equal amount of power |
| B. | One-third of total power |
| C. | Two-thirds of total power |
| D. | A power consumption equal to (‚à ö3VL) IL |
| Answer» B. One-third of total power | |
| 19. |
In a ‚Äö√ √ú-connected source feeding a Y-connected load%! |
| A. | Each phase voltage equals the difference of the corresponding load voltages |
| B. | Each phase voltage equals the corresponding load voltage |
| C. | Each phase voltage is one-third the corresponding load voltage |
| D. | Each phase voltage is 60° Ωut of phase with the corresponding load voltage |
| Answer» B. Each phase voltage equals the corresponding load voltage | |
| 20. |
A simple two-phase generator consists of two conductive loops separated by 90°, rotating in a magnetic field.%! |
| A. | True |
| B. | False |
| Answer» B. False | |
| 21. |
Polyphase is characterized by two or more sinusoidal voltages, each having a different phase angle.%! |
| A. | True |
| B. | False |
| Answer» B. False | |
| 22. |
In a certain three-wire Y-connected generator, the phase voltages are 2 kV. The magnitudes of the line voltages are%! |
| A. | 2,000 V |
| B. | 6,000 V |
| C. | 666 V |
| D. | 3,464 V |
| Answer» E. | |
| 23. |
If in a Y-connected ac generator, each phase voltage has a magnitude of 90 VRMS, what is the magnitude of each line voltage?%! |
| A. | 0 V |
| B. | 90 V |
| C. | 156 V |
| D. | 180 V |
| Answer» D. 180 V | |
| 24. |
Polyphase generators produce simultaneous multiple sinusoidal voltages that are separated by%! |
| A. | Certain constant phase angles |
| B. | Certain constant frequencies |
| C. | Certain constant voltages |
| D. | Certain constant currents |
| Answer» B. Certain constant frequencies | |
| 25. |
In a certain Y-Y system, the source phase currents each have a magnitude of 9 A. The magnitude of each load current for a balanced load condition is%! |
| A. | 3 A |
| B. | 6 A |
| C. | 9 A |
| D. | 27 A |
| Answer» D. 27 A | |
| 26. |
In a three-phase system, the voltages are separated by%! |
| A. | 45° |
| B. | 90° |
| C. | 120° |
| D. | 180° |
| Answer» D. 180¬¨‚àû | |
| 27. |
In a Y-connected circuit, the magnitude of each line current is%! |
| A. | One-third the phase current |
| B. | Three times the corresponding phase current |
| C. | Equal to the corresponding phase current |
| D. | Zero |
| Answer» D. Zero | |
| 28. |
In a ‚Äö√ √ú-connected generator, all of the phase voltages are%! |
| A. | Zero |
| B. | Equal in magnitude |
| C. | One-third of total |
| D. | One-sixth of total |
| Answer» C. One-third of total | |
| 29. |
*$_In a ‚Äö√ √ú-connected generator, all of the phase voltages are? |
| A. | Zero |
| B. | Equal in magnitude |
| C. | One-third of total |
| D. | One-sixth of total |
| Answer» C. One-third of total | |
| 30. |
%_The most common type of ac motor is the_% |
| A. | Single-phase induction motor |
| B. | Two-phase induction motor |
| C. | Three-phase induction motor |
| D. | Two-phase squirrel-cage motor |
| Answer» D. Two-phase squirrel-cage motor | |
| 31. |
_In a three-phase system, when the loads are perfectly balanced, the neutral current is$? |
| A. | Zero |
| B. | One-third of maximum |
| C. | Two-thirds of maximum |
| D. | At maximum |
| Answer» B. One-third of maximum | |
| 32. |
In a Y-Y source/load configuration, the$? |
| A. | Phase current, the line current, and the load current are all equal in each phase |
| B. | Phase current, the line current, and the load current are 120° Ωut of phase |
| C. | Phase current and the line current are in phase, and both are 120° Ωut of phase with the load current |
| D. | Line current and the load current are in phase, and both are out of phase with the phase current |
| Answer» B. Phase current, the line current, and the load current are 120¬¨‚àû ≈í¬©ut of phase | |
| 33. |
In a Y-Y source/load configuration, the? |
| A. | Phase current, the line current, and the load current are all equal in each phase |
| B. | Phase current, the line current, and the load current are 120° Ωut of phase |
| C. | Phase current and the line current are in phase, and both are 120° Ωut of phase with the load current |
| D. | Line current and the load current are in phase, and both are out of phase with the phase current |
| Answer» B. Phase current, the line current, and the load current are 120¬¨‚àû ≈í¬©ut of phase | |
| 34. |
In a ‚Äö√ √ú-connected source driving a ‚Äö√ √ú-connected load, the$ |
| A. | Load voltage and line voltage are one-third the source voltage for a given phase |
| B. | Load voltage and line voltage are two-thirds the source voltage for a given phase |
| C. | Load voltage and line voltage cancel for a given phase |
| D. | Load voltage, line voltage, and source phase voltage are all equal for a given phase |
| Answer» E. | |