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. |
The selection of an electric motor for any application depends on which of the following factors ? |
| A. | Electrical characteristics |
| B. | Mechanical characteristics |
| C. | Size and rating of motors |
| D. | All of the above |
| Answer» E. | |
| 2. |
For a particular application the type of electric-and control gear are determined by which of the following considerations ? |
| A. | Starting torque |
| B. | Conditions of environment |
| C. | Limitation on starting current |
| D. | All of the above |
| Answer» E. | |
| 3. |
While selecting an electric motor for a floor mill, which electrical characteristics will be of least significance ? |
| A. | Running characteristic |
| B. | Starting characteristics |
| C. | Efficiency |
| D. | Braking |
| Answer» E. | |
| 4. |
In squirrel cage induction motors which of the following methods of starting cannot be used ? |
| A. | Resistance in rotor circuit |
| B. | Resistance in stator circuit |
| C. | Auto transformer starting |
| D. | Start Delta starting |
| Answer» B. Resistance in stator circuit | |
| 5. |
Introduction of automation in production process has become possible only because of the use of |
| A. | An electric drive |
| B. | Group drives |
| C. | Individual and multi motor drives |
| D. | Individual Drive |
| Answer» D. Individual Drive | |
| 6. |
Choose the correct one. (* stands for multiplication, J represents the moment of inertia, w represents angular spee(D). |
| A. | J*d(w)/dt = Load torque Motor torque |
| B. | J*d(w)/dt = Load torque + Motor torque |
| C. | J*d(w)/dt = Motor torque Load torque |
| D. | J*d(w)/dt = Load torque * Motor torque |
| Answer» D. J*d(w)/dt = Load torque * Motor torque | |
| 7. |
The characteristics of drive for crane hoisting and lowering are which of the following ? |
| A. | Precise control |
| B. | Smooth movement |
| C. | Fast speed control |
| D. | All of the above |
| Answer» E. | |
| 8. |
Which of the following motors is preferred when quick speed reversal is the main consideration? |
| A. | Squirrel cage induction motor |
| B. | Wound rotor induction motor |
| C. | Synchronous motor |
| D. | D.C. motor |
| Answer» E. | |
| 9. |
While selecting motor for an air conditioner which of the following characteristics is of great importance ? |
| A. | Type of bearings |
| B. | Type of enclosure |
| C. | Noise |
| D. | Arrangement for power transmis sion |
| Answer» D. Arrangement for power transmis sion | |
| 10. |
The diameter of the rotor shaft for an electric motor depends on which of the following ? |
| A. | r.p.m. only |
| B. | Horse power only |
| C. | Horse power and r.p.m. |
| D. | Horse power, r.p.m. and power factor |
| Answer» D. Horse power, r.p.m. and power factor | |
| 11. |
In series motor which of the following methods can be used for changing the flux per pole? |
| A. | Tapped field control |
| B. | Diverter field control |
| C. | Series-parallel control |
| D. | Any of the above |
| Answer» E. | |
| 12. |
Which feature while selecting a motor for centrifugal pump will be of least significance? |
| A. | Starting characteristics |
| B. | Operating speed |
| C. | Horse power |
| D. | Speed control |
| Answer» E. | |
| 13. |
Besides a constant speed a synchronous rotor possesses which of the following advantages ? |
| A. | Lower cost |
| B. | Better efficiency |
| C. | High power factor |
| D. | All of the above |
| Answer» D. All of the above | |
| 14. |
While selecting an electric motor for a floor Mill, which electrical characteristics will be of least significance ? |
| A. | Running characteristics |
| B. | Starting characteristics |
| C. | Efficiency |
| D. | Breaking |
| Answer» E. | |
| 15. |
As compared to squirrel cage induction motor, a wound rotor induction motor is preferred when the major consideration is |
| A. | high starting torque |
| B. | low windage losses |
| C. | slow speed operation |
| D. | all of the above. |
| Answer» B. low windage losses | |
| 16. |
Wound rotor and squirrel-cage motors with high slip which develop maximum torque at stand still are used for |
| A. | machine tools |
| B. | presses and punches |
| C. | elevators |
| D. | all of the above. |
| Answer» C. elevators | |
| 17. |
In method of staging three phase induction motors the starting voltage is not reduced. |
| A. | auto-transformer |
| B. | star-delta |
| C. | slip ring |
| D. | any of the above |
| Answer» D. any of the above | |
| 18. |
In a centrifugal pump if the liquid to be pumped has density twice that of water, then the horse power required (as compared to that while pumping water) will be |
| A. | half |
| B. | same |
| C. | double |
| D. | four times. |
| Answer» D. four times. | |
| 19. |
Which of the following is an advantage of electric traction over other methods of traction ? |
| A. | Faster acceleration |
| B. | No pollution problems |
| C. | Better braking action |
| D. | All of the above |
| Answer» B. No pollution problems | |
| 20. |
Which of the following is the disadvantage of electric traction over other systems of traction ? |
| A. | Corrosion problems in the under-ground pipe work |
| B. | Short time power failure interrupts traffic for hours |
| C. | High capital outlay in fixed instal-lations beside route limitation |
| D. | Interference with communication lines |
| Answer» D. Interference with communication lines | |
| 21. |
Which of the following methods is used to control speed of 25 kV, 50 Hz single phase traction ? |
| A. | Reduced current method |
| B. | Tap changing control of transformer |
| C. | Series parallel operation of motors |
| D. | All of the above |
| Answer» C. Series parallel operation of motors | |
| 22. |
Speed-time curve of main line service differs from those of urban and suburban services on following account |
| A. | it has longer free running period |
| B. | it has longer coasting period |
| C. | accelerating and braking periods are comparatively smaller |
| D. | all of the above |
| Answer» E. | |
| 23. |
Calculate the useful power developed by a motor using the given data: P = 3000 W, I = 60 A, R = .4 . Assume frictional losses are 200 W and windage losses are 400 W. |
| A. | 970 W |
| B. | 960 W |
| C. | 980 W |
| D. | 990 W |
| Answer» C. 980 W | |
| 24. |
When a bogie negotiates a curve, reduction in adhesion occurs resulting in sliding. Thus sliding is acute when |
| A. | wheel base of axles is more |
| B. | degree of curvature is more |
| C. | both (A) and (B) |
| D. | none of the above |
| Answer» D. none of the above | |
| 25. |
The rate of acceleration on suburban orurban services is restricted by the consideration of |
| A. | Engine power |
| B. | Track curves |
| C. | Passenger Discomfort |
| D. | Track size |
| Answer» E. | |
| 26. |
The turn-o times of the devices in increasing order is ___________I. MOSFETII. BJTIII. IGBTIV. Thyristor |
| A. | I, III, II, IV |
| B. | I, II, III, IV |
| C. | III, I, II, IV |
| D. | III, II, IV, I |
| Answer» B. I, II, III, IV | |
| 27. |
Which of the following devices should be used as a switch for high power and high voltage application? |
| A. | GTO |
| B. | MOSFET |
| C. | TRIAC |
| D. | Thyristor |
| Answer» E. | |
| 28. |
In India, electrification of railway track was done for the first time in which of the following years ? |
| A. | 1820 1825 |
| B. | 1880 1885 |
| C. | 1925 1932 |
| D. | 1947 1954 |
| Answer» D. 1947 1954 | |
| 29. |
The conduction loss versus device current characteristic of a power MOSFET is best approximated by a ________ |
| A. | Straight line |
| B. | Rectangular hyperbola |
| C. | Parabola |
| D. | Exponential decaying functions |
| Answer» D. Exponential decaying functions | |
| 30. |
For which of the following locomotives the maintenance requirements are the least? |
| A. | Steam locomotives |
| B. | Diesel locomotives |
| C. | Electric locomotives |
| D. | Equal in all of the above |
| Answer» C. Electric locomotives | |
| 31. |
A pole changing type squirrel cage motor used in derricks has four, eight and twenty four poles. In this the lowest speed is used for |
| A. | lifting |
| B. | hoisting |
| C. | lowering |
| D. | landing the load. |
| Answer» E. | |
| 32. |
When smooth and precise speed control over a wide range is desired, the motor preferred is |
| A. | synchronous motor |
| B. | squirrel cage induction motor |
| C. | wound rotor induction motor |
| D. | dc motor. |
| Answer» E. | |
| 33. |
The characteristics of drive for crane hoisting and lowering are which off the following? |
| A. | Precise control |
| B. | Smooth movement |
| C. | Fast speed control |
| D. | All of the above |
| Answer» E. | |
| 34. |
Which feature, while selecting a.motor for centrifugal pump, will be of least significance ? |
| A. | Starting characteristics |
| B. | Operating speed |
| C. | Horse power |
| D. | Speed control |
| Answer» E. | |