MCQOPTIONS
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MCQOPTIONS
This section includes 354 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
To have an induced emf in the d.c. generator, there should be relative motion between the conductor and flux. The plane of rotation and plane of flux |
| A. | Should be parallel to each other |
| B. | Should not be parallel to each other |
| C. | Both (a) & (b) |
| D. | None of these |
| Answer» C. Both (a) & (b) | |
| 52. |
The Y - axis and X - axis in a circle diagram represents |
| A. | Voltage and current |
| B. | Current and power |
| C. | Power and voltage |
| D. | Current and voltage |
| Answer» B. Current and power | |
| 53. |
The wound rotor induction motor gives |
| A. | high stating torque |
| B. | moderate starting torque |
| C. | reduced starting torque |
| D. | all of these |
| Answer» B. moderate starting torque | |
| 54. |
The value of slip for motoring, generating and braking region respectively are |
| A. | S > 1, 0 = s = 1, s < 0 |
| B. | S < 0, 0 = s = 1, s > 1 |
| C. | 0 = s = 1, s > 1, s < 1 |
| D. | 0 = s = 1, s < 0, s > 1 |
| Answer» E. | |
| 55. |
The value of load angle δ and the internal machine angle ∅ for maximum power developed in synchronous motor is equal to |
| A. | 0°electrical, 0° electrical |
| B. | 0° electrical, 90° electrical |
| C. | 90° electrical, 0° electrical |
| D. | 90° electrical, 90° electrical |
| Answer» E. | |
| 56. |
The torque produced in the induction motor depends on the following factors 1. The part of rotating magnetic field which reacts with rotor and is responsible for producing emf. 2. The magnitude of rotor current in running condition. 3. The power factor of the rotor circuit in running condition. Which of the above statement is true? |
| A. | Only 1 |
| B. | 1 & 2 |
| C. | 2 & 3 |
| D. | 1, 2 and 3 |
| Answer» E. | |
| 57. |
The torque produced in a three phase induction motor is |
| A. | Directly proportional to the square of the induced emf in rotor |
| B. | Directly proportional to the induced emf in rotor |
| C. | Inversely proportional to the square of the induced emf in rotor |
| D. | Inversely proportional to the induced emf in rotor |
| Answer» B. Directly proportional to the induced emf in rotor | |
| 58. |
The torque equation of single phase induction motor contains a constant term superimposed over by a pulsating torque. The pulsating frequency is |
| A. | Equal to the supply frequency |
| B. | Twice of the supply frequency |
| C. | Half of the supply frequency |
| D. | None of these |
| Answer» C. Half of the supply frequency | |
| 59. |
The torque developed in d.c. shunt motor is |
| A. | Directly proportional to the armature current |
| B. | Directly proportional to the square of the armature current |
| C. | Inversely proportional to the armature current |
| D. | Inversely proportional to the square of armature current |
| Answer» B. Directly proportional to the square of the armature current | |
| 60. |
The tooth or slot harmonics in an induction motor is caused due to |
| A. | Variation of air gap reluctance |
| B. | Leakage flux |
| C. | Non sinusoidal nature of input voltage |
| D. | None of these |
| Answer» B. Leakage flux | |
| 61. |
The test which can be performed on the d.c. series motor is |
| A. | Brake test |
| B. | Hokinson’s test |
| C. | Swinburne’s test |
| D. | Field test |
| Answer» E. | |
| 62. |
The synchronous reactance of an alternator is equal to |
| A. | Leakage reactance of armature |
| B. | Armature reaction reactance |
| C. | Sum of leakage reactance and armature reaction reactance |
| D. | Difference of leakage reactance and armature reaction reactance |
| Answer» D. Difference of leakage reactance and armature reaction reactance | |
| 63. |
The synchronous motor as a synchronous condenser is used to |
| A. | Improve power factor |
| B. | Reduce hunting |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» B. Reduce hunting | |
| 64. |
The synchronous generator supplies leading power factor and lagging power factor respectively when it is |
| A. | Over excited, under excited |
| B. | Over excited, over excited |
| C. | Under excited, under excited |
| D. | Under excited, over excited |
| Answer» E. | |
| 65. |
The synchronous generator is loaded for obtaining zero power characteristics by using |
| A. | D.C. motor |
| B. | Lamp load |
| C. | Synchronous motor |
| D. | All of these |
| Answer» D. All of these | |
| 66. |
The stator of split phase induction motor has two windings, main winding and auxiliary winding. These windings are displaced in space by |
| A. | 30 electrical degrees |
| B. | 90 electrical degrees |
| C. | 120 electrical degrees |
| D. | 180 electrical degrees |
| Answer» C. 120 electrical degrees | |
| 67. |
The starting torque developed in the d.c. series motor and in d.c. shunt motor is |
| A. | High, low |
| B. | High, moderate |
| C. | Moderate, low |
| D. | Moderate, high |
| Answer» C. Moderate, low | |
| 68. |
The speed of permanent magnet d.c. motor cannot be controlled by |
| A. | Flux control method |
| B. | Rheostatic control method |
| C. | Electronic circuits |
| D. | None of these |
| Answer» B. Rheostatic control method | |
| 69. |
The speed in d.c. machine can be measured by using |
| A. | Anemometer |
| B. | Tachometer |
| C. | Voltmeter |
| D. | Ammeter |
| Answer» C. Voltmeter | |
| 70. |
The speed armature current characteristics of a d.c. series motor is |
| A. | Rectangular hyperbola |
| B. | Linear |
| C. | Parabolic |
| D. | Parabolic till saturation and then linear |
| Answer» B. Linear | |
| 71. |
The slip ring or wound rotor induction motor find its applications in |
| A. | lifts, cranes |
| B. | lathes |
| C. | drilling machines |
| D. | printing machines |
| Answer» B. lathes | |
| 72. |
The skin effect in a deep bar induction motor is maximum when rotor is |
| A. | At standstill |
| B. | Running at its maximum speed |
| C. | Running at no load |
| D. | Running at half load |
| Answer» B. Running at its maximum speed | |
| 73. |
The rotor resistance per phase on standstill and rotor reactance per phase on standstill of induction motor is |
| A. | Slip times the rotor resistance at standstill and slip times rotor reactance at standstill |
| B. | Same as rotor resistance at standstill and slip times rotor reactance at standstill |
| C. | Same as rotor resistance at standstill and same as rotor reactance at standstill |
| D. | Slip times the rotor resistance at standstill and same as rotor reactance at standstill |
| Answer» C. Same as rotor resistance at standstill and same as rotor reactance at standstill | |
| 74. |
The rotor frequency of a three phase induction motor is |
| A. | Slip times the supply frequency |
| B. | 1 / slip times the supply frequency |
| C. | Equal to the supply frequency |
| D. | None of these |
| Answer» B. 1 / slip times the supply frequency | |
| 75. |
The rotational or stray losses includes |
| A. | Iron losses only |
| B. | Iron losses, friction and windage losses |
| C. | Iron losses, copper losses, friction and windage losses |
| D. | None of these |
| Answer» D. None of these | |
| 76. |
The rotational losses in d.c. machines is equal to the |
| A. | Kinetic energy of armature |
| B. | Half of the kinetic energy of armature |
| C. | Square of the kinetic energy of armature |
| D. | Rate of change of kinetic energy |
| Answer» E. | |
| 77. |
The reluctance offered to the mmf wave is lowest when |
| A. | It is aligned with the field pole axis |
| B. | It is oriented at 90 degree to the field pole axis |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» B. It is oriented at 90 degree to the field pole axis | |
| 78. |
The prime movers which are used to drive non projected type rotors are |
| A. | I.C. engines |
| B. | Electric motors |
| C. | Steam turbines |
| D. | Both (b) & (c) |
| Answer» E. | |
| 79. |
The prime movers used to drive projected pole type alternator is |
| A. | Water turbines |
| B. | I.C. engines |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» D. None of these | |
| 80. |
The plot of power factor against the field current of synchronous motor is known as |
| A. | V-curves |
| B. | Inverted V-curves |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» C. Both (a) and (b) | |
| 81. |
The phasor addition of stator and rotor mmfs is possible in a smooth cylindrical synchronous generator because |
| A. | Mmfs of stator and rotor are stationary with respect to each other |
| B. | Mmf of stator is stationary and that of rotor is rotating |
| C. | Mmf of stator is rotating and that of rotor is stationary |
| D. | None of these |
| Answer» B. Mmf of stator is stationary and that of rotor is rotating | |
| 82. |
The performance of induction motor is effected by the harmonics in the |
| A. | Space variation of impressed voltage |
| B. | Time variation of impressed voltage |
| C. | Space variation of impressed current |
| D. | Time variation of impressed current |
| Answer» C. Space variation of impressed current | |
| 83. |
The output voltage of constant voltage transformer contains excessive harmonics which can be filtered out by using |
| A. | RC filter |
| B. | RL filter |
| C. | LC filter |
| D. | None of these |
| Answer» D. None of these | |
| 84. |
The open circuit voltage and short circuit current of a 3 phase, star connected alternator are 1050 V and 250 A respectively. Its field current is 12 A. Then the synchronous impedance of alternator will be |
| A. | 1.34 ohm |
| B. | 1.69 ohm |
| C. | 2.42 ohm |
| D. | 2.85 ohm |
| Answer» D. 2.85 ohm | |
| 85. |
The number of windings on the field of permanent magnet d.c. motor is |
| A. | More compared to shunt motor |
| B. | Less compared to shunt motor |
| C. | Absent |
| D. | None of these |
| Answer» D. None of these | |
| 86. |
The NO contact and NC contact of D.O.L. starter is normally |
| A. | Open, closed |
| B. | Closed, open |
| C. | Open, open |
| D. | Closed, closed |
| Answer» B. Closed, open | |
| 87. |
The most common method used to check for shorted windings is to perform |
| A. | Field test |
| B. | Drop test |
| C. | Regenerative test |
| D. | Brake test |
| Answer» C. Regenerative test | |
| 88. |
The method which can be used for the speed control of induction motor from stator side is |
| A. | V / f control |
| B. | Controlling number of stator poles to control Ns |
| C. | Adding rheostats in stator circuit |
| D. | All of these |
| E. | None of these |
| Answer» E. None of these | |
| 89. |
The method used for starting synchronous motor is/are |
| A. | Using pony motors |
| B. | Using damper windings |
| C. | As a slip ring induction motor |
| D. | All of the above |
| Answer» E. | |
| 90. |
The load carried by V - V connection is |
| A. | 47.7% of the original load |
| B. | 57.7% of the original load |
| C. | 67.7% of the original load |
| D. | 87.7% of the original load |
| Answer» C. 67.7% of the original load | |
| 91. |
The leakage flux in the armature of alternator makes the armature winding |
| A. | Inductive in nature |
| B. | Capacitive in nature |
| C. | Resistive in nature |
| D. | All of these |
| Answer» B. Capacitive in nature | |
| 92. |
The induction generator is |
| A. | Self exciting |
| B. | Separately exciting |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» C. Both (a) and (b) | |
| 93. |
The increase in mechanical torque in case of alternator will |
| A. | Increase the armature current and reduce the power factor |
| B. | Increase the armature current and improve the power factor |
| C. | Decrease the armature current and improve the power factor |
| D. | Decrease the armature current and reduce the power factor |
| Answer» C. Decrease the armature current and improve the power factor | |
| 94. |
The hysteresis loss in a transformer is minimized by using |
| A. | Laminated sheets of steel |
| B. | Special grade of heat treated grain oriented silicon steel |
| C. | Bracing of transformer assemblies |
| D. | Proper design of winding |
| Answer» C. Bracing of transformer assemblies | |
| 95. |
The hysteresis motor are mainly used in tape recorders because |
| A. | Of its extremely steady torque |
| B. | Constant speed |
| C. | Reduced initial current |
| D. | None of these |
| Answer» B. Constant speed | |
| 96. |
The high leakage impedance transformers are suitable for the applications of |
| A. | Arc welding |
| B. | Personal computers |
| C. | Street lights |
| D. | Electric lamp |
| Answer» B. Personal computers | |
| 97. |
The globules of water present in oil may result directly in a breakdown. This can be prevented by |
| A. | Proper insulation |
| B. | Isolation of oil from air by using an inert gas |
| C. | Heating the tank |
| D. | None of these |
| Answer» C. Heating the tank | |
| 98. |
The generating action and motoring action in d.c. motor is determined by |
| A. | Fleming’s left hand rule, Fleming’s right hand rule |
| B. | Both by Fleming’s left hand rule |
| C. | Both by Fleming’s right hand rule |
| D. | Fleming’s right hand rule, Fleming’s left hand rule |
| Answer» E. | |
| 99. |
The flux under the unshaded pole of shaded pole induction motor |
| A. | Is in equal phase of flux under the shaded pole |
| B. | Lags the flux under the shaded pole |
| C. | Leads the flux under the shaded pole |
| D. | None of these |
| Answer» D. None of these | |
| 100. |
The factor by which there is reduction in the emf due to distribution of coils is called distribution factor. It is given by |
| A. | sin (β / 2m) / msin(β / 2) |
| B. | sin(β / m) / msin(mβ / 2) |
| C. | sin(m β/2) / msin(β / 2) |
| D. | msin(β / 2) / sin(m β / 2) |
| Answer» D. msin(β / 2) / sin(m β / 2) | |