MCQOPTIONS
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MCQOPTIONS
This section includes 14 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Machines knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A_UNIFORMLY_DISTRIBUTED_WINDING_ON_THE_STATOR_HAS_THREE_FULL_PITCHED_COILS,_EACH_COIL_HAVING_N_TURNS_AND_EACH_TURN_CARRYING_A_CURRENT_I._THE_MMF_PRODUCED_BY_THE_WINDING_IS?$ |
| A. | sinusoidal in waveform with an amplitude 3Ni |
| B. | sinusoidal in waveform with an amplitude 3Ni/2 |
| C. | trapezoidal in waveform with an amplitude of 3Ni |
| D. | trapezoidal in waveform with an amplitude of 3Ni/2 |
| Answer» E. | |
| 2. |
A winding of 20 full pitched series turns, distributed over a band of 60° under each pole, carries a current of 3A. The winding produces a uniform current sheet of density (in AT’s per electrical radiangs) of$# |
| A. | 180/Π |
| B. | 120/Π |
| C. | 90/Π |
| D. | 60/Π |
| Answer» B. 120/‚âà√≠‚Äö√тĆ | |
| 3. |
MMF_produced_by_one_N-turn_coil_carrying_a_current_i_is_____________$ |
| A. | rectangular of amplitude Ni/2 |
| B. | trapezoidal of amplitude Ni/2 |
| C. | rectangular of amplitude Ni |
| D. | trapezoidal of amplitude Ni |
| Answer» B. trapezoidal of amplitude Ni/2 | |
| 4. |
The armature MMF wave in a DC machine is triangluar and |
| A. | rotates with respect to stator |
| B. | is stationary with respect to stator |
| C. | rotates with respect to armature |
| D. | is stationary with respect to armature |
| Answer» E. | |
| 5. |
In a DC machine, z,p,Ia and a are respectively the number of conductors, number of poles, armature current and number of parallel paths. The peak value of fundamental component of armature MMF wave is ____________ |
| A. | 8/Π[(z/2p)(I<sub>a</sub>/a)]. |
| B. | 8/Π<sup>2</sup>[(z/p)(I<sub>a</sub>/a)]. |
| C. | 4/Π[(z/2p)(I<sub>a</sub>/a)]. |
| D. | 8/Π<sup>2</sup>[(z/p)(I<sub>a</sub>/a)]. |
| Answer» E. | |
| 6. |
A_sinusoidal_current_sheet_in_a_rotating_electrical_machine_has_peak_value_along_q-axis._The_peak_value_of_sinusoidal_MMF_would_be |
| A. | in phase with current peak |
| B. | 90° lagging the current peak |
| C. | 90° leading the current peak |
| D. | may lag or lead depending upon the type of machine |
| Answer» D. may lag or lead depending upon the type of machine | |
| 7. |
A current sheet with sinusoidal current produces? |
| A. | sinusoidal MMF wave lagging it by 90° |
| B. | sinusoidal MMF wave leading it by 90° |
| C. | trapezoidal MMF wave leading it by 90° |
| D. | trapezoidal MMF wave lagging it by 90° |
| Answer» C. trapezoidal MMF wave leading it by 90¬¨¬®‚Äö√†√ª | |
| 8. |
Which of the following statements are correct regarding the current sheet? |
| A. | it is a thin strip of conducting material carrying the current in the dot |
| B. | it is wrapped around stator or rotor |
| C. | it develops MMF identical to that produced by the winding it replaces |
| D. | Any of the mentioned |
| Answer» E. | |
| 9. |
The armature MMF wave in a DC machine is ____________ |
| A. | sinusoidal and depends on the speed |
| B. | square and independent of speed |
| C. | triangular and depends on speed |
| D. | triangular and independent of speed |
| Answer» E. | |
| 10. |
Peak value of fundamental component of MMF produced by one N-turn coil carrying a current ‘i’ is ____________$ |
| A. | 4/Π(Ni) |
| B. | 2/Π(Ni) |
| C. | 1/Π(Ni) |
| D. | 1/2Π(Ni) |
| Answer» C. 1/‚âà√≠‚Äö√тĆ(Ni) | |
| 11. |
If the current in a coil is AC, the amplitude of MMF |
| A. | varies with time but not with space |
| B. | varies with space but not with time |
| C. | varies with both space and time |
| D. | doesn’t vary with both space and time |
| Answer» B. varies with space but not with time | |
| 12. |
If the current in the coil is DC, then MMF doesn’t vary with ____________$ |
| A. | space |
| B. | time |
| C. | both space and time |
| D. | None of the mentioned |
| Answer» D. None of the mentioned | |
| 13. |
A knowledge of the air gap flux distribution in a machine helps in determining the |
| A. | generated EMF waveform and its magnitude |
| B. | electrical torque |
| C. | winding MMF |
| D. | both generated EMF waveform and electrical torque |
| Answer» E. | |
| 14. |
The winding MMF in rotating machines depends on |
| A. | winding arrangement |
| B. | winding current |
| C. | air gap length,slot openings etc |
| D. | both winding arrangement and winding current |
| Answer» E. | |