MCQOPTIONS
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MCQOPTIONS
This section includes 80 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 synchronous speed of a linear induction motor does not depend on |
| A. | Width of pole pitch |
| B. | Number of poles |
| C. | Supply frequency |
| D. | Any of the above |
| Answer» C. Supply frequency | |
| 2. |
When load is removed, .......motor will run at the highest speed. |
| A. | Shunt |
| B. | Cumulative – compound |
| C. | Differential compound |
| D. | Series |
| Answer» E. | |
| 3. |
The Ta/Ia graph of a dc series motor is a |
| A. | Parabola from no load to overload |
| B. | Straight line throughout |
| C. | Parabola throughout |
| D. | Parabola upto full load and a straight line at overloads |
| Answer» E. | |
| 4. |
A series motor is best suited for driving |
| A. | Lathes |
| B. | Cranes and hoists |
| C. | Shears and punches |
| D. | Machine tools |
| Answer» C. Shears and punches | |
| 5. |
A dc motor can be looked upon as dc generator with the power flow |
| A. | Reduced |
| B. | Reversed |
| C. | Increased |
| D. | Modified |
| Answer» C. Increased | |
| 6. |
The induced emf in the armature conductors of a dc motor is |
| A. | Sinusoidal |
| B. | Trapezoidal |
| C. | Rectangular |
| D. | Alternating |
| Answer» B. Trapezoidal | |
| 7. |
The Eb/V ratio of a dc motor is an indication of its |
| A. | Efficiency |
| B. | Speed regulation |
| C. | Starting torque |
| D. | Running Torque |
| Answer» B. Speed regulation | |
| 8. |
The counter emf of dc motor |
| A. | Often exceeds the supply voltage |
| B. | Aids the applied voltage |
| C. | Helps in energy conversion |
| D. | Regulates its armature voltage |
| Answer» D. Regulates its armature voltage | |
| 9. |
In a DC motor, unidirectional torque is produced with the help of |
| A. | Brushes |
| B. | Commutator |
| C. | End-plates |
| D. | Both a and b |
| Answer» E. | |
| 10. |
Regarding Ward-Leonard system of speed control which statement is false? |
| A. | It is usually used where wide and very sensitive speed control is required |
| B. | It is used for motors having ratings from 750kW to 4000Kw |
| C. | Capital outlay involved in the system is right since it uses two extra machines |
| D. | It gives a speed range of 10:1 but in one direction only |
| Answer» E. | |
| 11. |
The speed of a dc motor can be controlled by varying |
| A. | its flux per pole |
| B. | resistance of armature circuit |
| C. | applied voltage |
| D. | all of the above |
| Answer» E. | |
| 12. |
If a transformer primary is energised from a square wave voltage source, its output voltage will be |
| A. | A square wave. |
| B. | A sine wave |
| C. | A triangular wave. |
| D. | A pulse wave. |
| Answer» B. A sine wave | |
| 13. |
The generation voltage in India is usually |
| A. | between 11 KV and 33 KV |
| B. | between 132 KV and 400 KV. |
| C. | between 400 KV and 700 KV. |
| D. | None of the above. |
| Answer» B. between 132 KV and 400 KV. | |
| 14. |
The power factor of a squirrel cage induction motor is |
| A. | low at light load only |
| B. | low at heavy load only. |
| C. | low at light and heavy load both |
| D. | low at rated load only. |
| Answer» B. low at heavy load only. | |
| 15. |
In a 3 – phase induction motor the maximum torque |
| A. | is proportional to rotor resistance r2 . |
| B. | does not depend on r2 . |
| C. | is proportional to square root of r2 . |
| D. | is proportional to square of r2 . |
| Answer» C. is proportional to square root of r2 . | |
| 16. |
The current from the stator of an alternator is taken out to the external load circuit throu |
| A. | slip rings. |
| B. | commutator segments. |
| C. | solid connections. |
| D. | carbon brushes. |
| Answer» D. carbon brushes. | |
| 17. |
The ‘sheath’ is used in cable to |
| A. | provide strength to the cable. |
| B. | provide proper insulation |
| C. | prevent the moisture from entering the cable. |
| D. | avoid chances of rust on strands |
| Answer» B. provide proper insulation | |
| 18. |
stepper motor is |
| A. | a dc motor. |
| B. | a single-phase ac motor. |
| C. | a multi-phase motor. |
| D. | a two phase motor. |
| Answer» E. | |
| 19. |
In case of a universal motor, torque pulsation is minimized by _________. |
| A. | load inertia |
| B. | rotor inertia |
| C. | both rotor and load inertia |
| D. | none of the above |
| Answer» D. none of the above | |
| 20. |
In a capacitor start single-phase induction motor, the capacitor is connected |
| A. | in series with main winding |
| B. | in series with auxiliary winding. |
| C. | in series with both the windings. |
| D. | in parallel with auxiliary winding. |
| Answer» C. in series with both the windings. | |
| 21. |
The size of the feeder is determined primarily by |
| A. | the current it is required to carry. |
| B. | the percent variation of voltage in the feede |
| C. | the voltage across the feeder |
| D. | the distance of transmission. |
| Answer» B. the percent variation of voltage in the feede | |
| 22. |
The size of a conductor used in power cables depends on the |
| A. | operating voltage. |
| B. | power factor. |
| C. | current to be carried. |
| D. | type of insulation used |
| Answer» D. type of insulation used | |
| 23. |
The most suitable servomotor for low power applications is |
| A. | a dc series motor |
| B. | a dc shunt motor |
| C. | an ac two-phase induction motor. |
| D. | an ac series motor |
| Answer» C. an ac two-phase induction motor. | |
| 24. |
A motor which can conveniently be operated at lagging as well as leading power factors is the |
| A. | squirrel cage induction motor. |
| B. | wound rotor induction motor. |
| C. | synchronous motor |
| D. | DC shunt motor |
| Answer» D. DC shunt motor | |
| 25. |
The current from the stator of an alternator is taken out to the external load circuit through |
| A. | slip rings |
| B. | commutator segments. |
| C. | solid connections. |
| D. | carbon brushes. |
| Answer» D. carbon brushes. | |
| 26. |
The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be |
| A. | 3.6 V. |
| B. | 2.5 V |
| C. | 3.0 V. |
| D. | 6.0 V. |
| Answer» D. 6.0 V. | |
| 27. |
In a transformer the voltage regulation will be zero when it operates at |
| A. | unity p.f. |
| B. | leading p.f. |
| C. | lagging p.f. |
| D. | zero p.f. leading |
| Answer» C. lagging p.f. | |
| 28. |
In a D.C. machine, the armature mmf is |
| A. | stationary w.r.t. armature. |
| B. | rotating w.r.t. field. |
| C. | stationary w.r.t. field |
| D. | rotating w.r.t. brushes |
| Answer» D. rotating w.r.t. brushes | |
| 29. |
If a transformer primary is energized from a square wave voltage source, its output voltage will be |
| A. | A square wave. |
| B. | A sine wave. |
| C. | A triangular wave |
| D. | A pulse wave |
| Answer» B. A sine wave. | |
| 30. |
A hysteresis motor |
| A. | is not a self-starting motor |
| B. | is a constant speed motor. |
| C. | needs dc excitation. |
| D. | can not be run in reverse speed |
| Answer» C. needs dc excitation. | |
| 31. |
When a synchronous motor is running at synchronous speed, the damper winding produces |
| A. | damping torque |
| B. | eddy current torque |
| C. | torque aiding the developed torque |
| D. | no torque. |
| Answer» E. | |
| 32. |
The generation voltage is usually |
| A. | between 11 KV and 33 KV |
| B. | between 132 KV and 400 KV |
| C. | between 400 KV and 700 KV. |
| D. | None of the above |
| Answer» B. between 132 KV and 400 KV | |
| 33. |
In a stepper motor the angular displacement |
| A. | can be precisely controlled |
| B. | it cannot be readily interfaced with micro computer based controller |
| C. | the angular displacement cannot be precisely controlled. |
| D. | it cannot be used for positioning of work tables and tools in NC machines. |
| Answer» E. | |
| 34. |
Out of the following methods of heating the one which is independent of supply frequency is |
| A. | electric arc heating |
| B. | induction heating |
| C. | electric resistance heating |
| D. | dielectric heating |
| Answer» D. dielectric heating | |
| 35. |
The D.C. series motor should always be started with load because |
| A. | at no load, it will rotate at dangerously high speeD. |
| B. | it will fail to start |
| C. | it will not develop high starting torque. |
| D. | all are true |
| Answer» B. it will fail to start | |
| 36. |
The two windings of a transformer is |
| A. | conductively linked |
| B. | inductively linked. |
| C. | not linked at all |
| D. | electrically linked. |
| Answer» C. not linked at all | |
| 37. |
The frequency of the rotor current in a 3 phase 50 Hz, 4 pole induction motor at full load speed is about |
| A. | 50 Hz |
| B. | 20 Hz |
| C. | 2 Hz. |
| D. | Zero. |
| Answer» C. 2 Hz. | |
| 38. |
The emf induced in the primary of a transformer |
| A. | is in phase with the flux. |
| B. | lags behind the flux by 90 degree |
| C. | leads the flux by 90 degree |
| D. | is in phase opposition to that of flux |
| Answer» D. is in phase opposition to that of flux | |
| 39. |
A salient pole synchronous motor is running at no loaD. Its field current is switched off. The motor will |
| A. | come to stop. |
| B. | continue to run at synchronous speeD. |
| C. | continue to run at a speed slightly more than the synchronous speeD |
| D. | continue to run at a speed slightly less than the synchronous speeD. |
| Answer» C. continue to run at a speed slightly more than the synchronous speeD | |
| 40. |
A 220V, 15kW,1000rpm shunt motor with armature resistance of 0.25Ω, has a rated line current of 68A and a rated field current of 2.2A. The change in field flux required to obtain a speed of 1600 rpm while drawing a line current of 52.8A and a field current of 1.8A is [GATE2012] |
| A. | 18.18% increase |
| B. | 18.18% decrease |
| C. | 36.36% increase |
| D. | 36.36% decrease |
| Answer» E. | |
| 41. |
The locked rotor current in a 3-phase, star connected 15kW, 4-pole, 230V, 50Hz induction motor at rated conditions is 50A. Neglecting losses and magnetizing current, the approximate locked rotor line current drawn when the motor is connected to a 236V, 57Hz supply is [GATE2012] |
| A. | 58.5A |
| B. | 45.0A |
| C. | 45.7A |
| D. | 55.6A |
| Answer» C. 45.7A | |
| 42. |
A single phase 10kVA, 50 Hz transformer with 1kV primary winding draws 0.5A and 55W, at rated voltage and frequency, on no loaD. A second transformer has a core with all its linear √2 times the corresponding dimensions of the first transformer. The core material and lamination thickness are the same in both transformers. The primary windings of both the transformers have the same number of turns. If a rated voltage of 2kV at 50Hz is applied to the primary of the second transformer, then the no load current and power, respectively, are [GATE2012] |
| A. | 0.7 A,77.8W |
| B. | 0.7A,155.6 W |
| C. | 1A,110W |
| D. | 1A,220W |
| Answer» C. 1A,110W | |
| 43. |
A field excitation of 20A in a certain alternator results in an armature current of 400A in short circuit and a terminal voltage of 2000V on open circuit. The magnitude of the internal voltage drop within the machine at a load current of 200A is [GATE2009] |
| A. | 1V |
| B. | 10V |
| C. | 100V |
| D. | 1000V |
| Answer» E. | |
| 44. |
When load on a synchronous motor is increased its armature current is increased provided it is |
| A. | normally excited |
| B. | over excited |
| C. | under exciter |
| D. | all of the above |
| Answer» E. | |
| 45. |
In a synchronous machine when the rotor speed becomes more than the synchronous speed during hunting, the damping bars develop |
| A. | synchronous motor torque |
| B. | dc motor torque |
| C. | induction motor torque |
| D. | induction generator torque |
| Answer» E. | |
| 46. |
The angle between the synchronous rotating stator flux and rotor poles of a synchronous motor is |
| A. | Synchronizing angle |
| B. | Torque angle |
| C. | Power factor angle |
| D. | Slip angle |
| Answer» C. Power factor angle | |
| 47. |
The maximum value of torque angle a in a synchronous motor is.......degrees electrical |
| A. | 45 |
| B. | 90 |
| C. | between 45 and 90 |
| D. | below 60 |
| Answer» C. between 45 and 90 | |
| 48. |
A synchronous motor connected to infinite busbars has at constant full-load, 100% excitation and unity pf. On changing the excitation only, the armature current will have |
| A. | leading pf with under-excitation |
| B. | leading pf with over excitation |
| C. | . lagging pf with over excitation |
| D. | no change of pf |
| Answer» C. . lagging pf with over excitation | |
| 49. |
The direction of rotation of a synchronous motor can be reversed by reversing |
| A. | Current to the field winding |
| B. | Supply phase sequence |
| C. | Polarity of rotor poles |
| D. | None of the above |
| Answer» C. Polarity of rotor poles | |
| 50. |
If the field of a synchronous motor is under excited, the power factor will be |
| A. | Lagging |
| B. | Leading |
| C. | Unity |
| D. | More than unity |
| Answer» B. Leading | |