MCQOPTIONS
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MCQOPTIONS
This section includes 657 Mcqs, each offering curated multiple-choice questions to sharpen your Testing Subject knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
The direction of rotation of an hysteresis motor is determined by |
| A. | interchanging the supply leads |
| B. | position of shaded pole with respect to main pole |
| C. | retentivity of the rotor material |
| D. | none of these |
| Answer» C. retentivity of the rotor material | |
| 2. |
Direction of rotation of a split phase motor can be reversed by reversing the connection of |
| A. | running winding only |
| B. | starting winding only |
| C. | either (A) or (B) |
| D. | both (A) and (B) |
| Answer» D. both (A) and (B) | |
| 3. |
For which of the applications a reluctance motor is preferred ? |
| A. | Electric shavers |
| B. | Refrigerators |
| C. | Signalling and timing devices |
| D. | Lifts and hoists |
| Answer» D. Lifts and hoists | |
| 4. |
The rotor developed by a single-phase motor at starting is |
| A. | more than rated torque |
| B. | rated torque |
| C. | less than the rated torque |
| D. | zero |
| Answer» E. | |
| 5. |
The shaded pole motor is used for |
| A. | high starting torque |
| B. | low starting torque |
| C. | medium starting torque |
| D. | very high starting torque |
| Answer» C. medium starting torque | |
| 6. |
The power factor of a single-phase induction motor is usually |
| A. | lagging |
| B. | always leading |
| C. | unity |
| D. | unity to 0.8 leading |
| Answer» B. always leading | |
| 7. |
In split-phase motor auxiliary winding is of |
| A. | thick wire placed at the bottom of the slots |
| B. | thick wire placed at the top of the slots |
| C. | thin wire placed at the top of the slots |
| D. | thin wire placed at the bottom of the slots |
| Answer» D. thin wire placed at the bottom of the slots | |
| 8. |
The speed control of universal motor used for sewing machines is by |
| A. | friction |
| B. | varying the resistance |
| C. | tapping the field |
| D. | centrifugal mechanism |
| Answer» C. tapping the field | |
| 9. |
In case of high speed universal motor which of the following needs more attention ? |
| A. | End play |
| B. | Air gap |
| C. | Insulation in rotor |
| D. | Balancing of rotor |
| Answer» E. | |
| 10. |
Which of the following single-phase motors is suitable for timing and control purposes ? |
| A. | Reluctance motor |
| B. | Series motor |
| C. | Repulsion motor |
| D. | Universal motor |
| Answer» B. Series motor | |
| 11. |
Short-circuiter is used in |
| A. | Repulsion induction motor |
| B. | Repulsion motor |
| C. | Repulsion start induction run motor |
| D. | None of the above |
| Answer» D. None of the above | |
| 12. |
In a capacitor start single-phase motor, when capacitor is replaced by a resistance |
| A. | torque will increase |
| B. | the motor will consume less power |
| C. | motor will run in reverse direction |
| D. | motor will continue to run in same direction |
| Answer» E. | |
| 13. |
The value of starting capacitor of a fractional horse power motor will be |
| A. | 100 uF |
| B. | 200 uF |
| C. | 300 uF |
| D. | 400 uF |
| Answer» D. 400 uF | |
| 14. |
Which of the following statements regarding repulsion-start induction motor is incorrect ? |
| A. | It requires more maintenance of commutator and other mechanical devices |
| B. | It makes quite a bit of noise on starting |
| C. | In fractional horse power motors, it has replaced the capacitor motors |
| D. | It is not easily reversed |
| Answer» D. It is not easily reversed | |
| 15. |
In a ceilingfan employing capacitor run motor |
| A. | secondary winding surrounds the primary winding |
| B. | primary winding surrounds the secondary winding |
| C. | both are usual arrangements |
| D. | none of the above |
| Answer» B. primary winding surrounds the secondary winding | |
| 16. |
Burning out of winding is due to |
| A. | short circuited capacitor |
| B. | capacitor value hiving changed |
| C. | open circuiting of capacitor |
| D. | none of the above |
| Answer» B. capacitor value hiving changed | |
| 17. |
In split phase motor main winding is of |
| A. | thin wire placed at the top of the slots |
| B. | thin wire placed at the bottom of the slots |
| C. | thick wire placed at the bottom of the slots |
| D. | thick wire placed at the top of the? slots |
| Answer» D. thick wire placed at the top of the? slots | |
| 18. |
A shaded pole motor can be used for |
| A. | toys |
| B. | hair dryers |
| C. | circulators |
| D. | any of the above |
| Answer» E. | |
| 19. |
Which of the following motors has highest starting torque ? |
| A. | Repulsion motor |
| B. | Shaped pole motor |
| C. | Capacitor-start motor |
| D. | Split-phase motor |
| Answer» D. Split-phase motor | |
| 20. |
A universal motor can run on |
| A. | D.C. only |
| B. | D.C. only |
| C. | either A.C. or D.C. |
| D. | none of the above |
| Answer» D. none of the above | |
| 21. |
A shaded pole motor does not possess |
| A. | centrifugal switch |
| B. | capacitor |
| C. | commutator |
| D. | all of the above |
| Answer» E. | |
| 22. |
In a A.C. series motor armature coils are usually connected to commutator |
| A. | through resistance |
| B. | through reactances |
| C. | through capacitors |
| D. | solidly |
| Answer» B. through reactances | |
| 23. |
Which of the following statements regarding reluctance-start motor is incorrect ? |
| A. | It is similar to reluctance motor |
| B. | It is basically an induction motor and not a synchronous one |
| C. | So far as its basic working principle is concerned, it is similar to shaded pole motor |
| D. | the air-gap between rotor and salient poles is non- uniform |
| Answer» B. It is basically an induction motor and not a synchronous one | |
| 24. |
The speed of a universal motor is usually reduced by using |
| A. | gearing |
| B. | belts |
| C. | brakes |
| D. | chains |
| Answer» B. belts | |
| 25. |
In a shaded pole motor, the shading coil usually consist of |
| A. | a single turn of heavy wire which is in parallel with running winding |
| B. | a single turn of heavy copper wire which is short-circuited and carries only induced current |
| C. | a multilayer fine gauge copper wire in parallel with running winding |
| D. | none of the above |
| Answer» C. a multilayer fine gauge copper wire in parallel with running winding | |
| 26. |
After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on |
| A. | running winding |
| B. | rotor winding |
| C. | field winding |
| D. | compensating winding |
| Answer» B. rotor winding | |
| 27. |
Which of the following motor will have relatively higher power factor ? |
| A. | Capacitor run motor |
| B. | Shaded pole motor |
| C. | Capacitor start motor |
| D. | Split phase motor |
| Answer» B. Shaded pole motor | |
| 28. |
As hysteresis motors are free from mechanical and magnetic vibrations therefore these are considered as suitable for |
| A. | fans |
| B. | blowers |
| C. | sound equipment |
| D. | mixer grinders |
| Answer» D. mixer grinders | |
| 29. |
The starting winding of a single-phase motor is placed in |
| A. | Armature |
| B. | Field |
| C. | Rotor |
| D. | Stator |
| Answer» E. | |
| 30. |
Which of the following motors is used in a situation where load increases with speed ? |
| A. | Induction motor |
| B. | Three-phase series motor |
| C. | Schrage motor |
| D. | Hysteresis motor |
| Answer» C. Schrage motor | |
| 31. |
The wattage of motor for driving domestic sewing machine will be around |
| A. | 100 to 150 W |
| B. | 40 to 75 W |
| C. | 10 to 30 W |
| D. | 5 to 10 W |
| Answer» B. 40 to 75 W | |
| 32. |
If a D.C. series motor is operated on A.C. supply, it will |
| A. | spark excessively |
| B. | have poor efficiency |
| C. | have poor power factor |
| D. | all of the above |
| Answer» E. | |
| 33. |
A hysteresis motor works on the principle of |
| A. | hysteresis loss |
| B. | magnetisation of rotor |
| C. | eddy current loss |
| D. | electromagnetic induction |
| Answer» B. magnetisation of rotor | |
| 34. |
Which of the following statements regarding a reluctance motor is incorrect ? |
| A. | It cannot be reversed, ordinarily |
| B. | It requires no D.C. field excitation for its operation |
| C. | It is nothing else but a single-phase, salient pole synchronous-induction motor |
| D. | Its squirrel cage-rotor is of unsym-metrical magnetic construction in order to vary reluc-tance path between stator and rotor |
| Answer» B. It requires no D.C. field excitation for its operation | |
| 35. |
In a split phase motor |
| A. | the starting winding is connected through a centrifugal switch |
| B. | the running winding is connected through a centrifugal switch |
| C. | both starting and running windings are connected through a centrifugal switch |
| D. | centrifugal switch is used to control supply voltage |
| Answer» B. the running winding is connected through a centrifugal switch | |
| 36. |
A.C. series motor as compared to D.C. series motor has |
| A. | smaller brush width |
| B. | less number of field turns |
| C. | more number of armature turns |
| D. | less air gap |
| E. | all of the above |
| Answer» F. | |
| 37. |
If the centrifugal switch does not open at 70 to 80 percent of synchronous speed of motor, it would result in |
| A. | Damage to the starting winding |
| B. | Damage to the centrifugal switch |
| C. | Overloading of running winding |
| D. | None of the above |
| Answer» B. Damage to the centrifugal switch | |
| 38. |
In a split phase motor, the running winding should have |
| A. | high resistance and low inductance |
| B. | low resistance and high inductance |
| C. | high resistance as well as high inductance |
| D. | low resistance as well as low inductiance |
| Answer» C. high resistance as well as high inductance | |
| 39. |
Single phase induction motor usually operates on |
| A. | 0.6 power factor lagging |
| B. | 0.8 power factor lagging |
| C. | 0.8 power factor leading |
| D. | unity power factor |
| Answer» B. 0.8 power factor lagging | |
| 40. |
Which of the following motors will operate at high power factor ? |
| A. | Shaped pole motor |
| B. | Split phase motor |
| C. | Capacitor start motor |
| D. | Capacitor run motor |
| Answer» E. | |