MCQOPTIONS
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MCQOPTIONS
This section includes 252 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
What kind of motor employs the skein winding made use of? |
| A. | maximum horse power single phase induction motor |
| B. | fractional horse power single phase induction motor |
| C. | minimum horse power single phase induction motor |
| D. | zero horse power single phase induction motor |
| Answer» C. minimum horse power single phase induction motor | |
| 52. |
How many steps are involved in the construction of single phase induction motor? |
| A. | 3 |
| B. | 4 |
| C. | 5 |
| D. | 6 |
| Answer» D. 6 | |
| 53. |
In DC machines the residual magnetism is present. The order of residual magnetism is |
| A. | 2 to 3 per cent |
| B. | 10 to 15 per cent |
| C. | 20 to 25 per cent |
| D. | 50 to 75 per cent |
| Answer» B. 10 to 15 per cent | |
| 54. |
The armature shaft of a DC motor must be able to withstand |
| A. | bending moment due to weight of the armature. |
| B. | any unbalanced magnetic pull on the armature core. |
| C. | twisting stains due to transmission of torque. |
| D. | bending moment, unbalanced magnetic pull and twisting stains |
| Answer» E. | |
| 55. |
Which power is mentioned on a name plate of a motor? |
| A. | gross power |
| B. | power drawn in kva |
| C. | power drawn in kw |
| D. | output power available at the shaft |
| Answer» E. | |
| 56. |
In DC motor, which of the following part can sustain the maximum temperature rise? |
| A. | field winding |
| B. | commutator |
| C. | slip rings |
| D. | armature winding |
| Answer» B. commutator | |
| 57. |
What will happen if DC shunt motor is connected across AC supply? |
| A. | will run at normal speed |
| B. | will not run |
| C. | will run at lower speed |
| D. | burn due to heat produced in the field winding |
| Answer» E. | |
| 58. |
Load torques can be classified into how many types? |
| A. | three |
| B. | two |
| C. | four |
| D. | five |
| Answer» C. four | |
| 59. |
For a 100 hp 250 V, compound dc motor with compensating winding has a field current of 5 A to produce a voltage of 250 V at 1200 rpm. What will be the shunt field current of this machine at no load? |
| A. | 5 a |
| B. | 5.6 a |
| C. | 4 a |
| D. | 0 a |
| Answer» B. 5.6 a | |
| 60. |
The speed torque of the differential compound dc motor is shown below. What conclusions can be made? |
| A. | this is an unstable machine |
| B. | there is regenerative increment in the speed |
| C. | this is impractical to be used |
| D. | all of the mentioned |
| Answer» E. | |
| 61. |
A student is given a differential compound motor and he has been asked to make it start. How will he try? |
| A. | by shorting series field at start |
| B. | to run as shunt motor at start |
| C. | by making rated current at start |
| D. | all of the mentioned |
| Answer» E. | |
| 62. |
Choose the best option which identifies about the below characteristics. |
| A. | (1)series motor (2) cumulative compound motor (3) shunt motor |
| B. | (1)cumulative compound motor (2) series motor (3) shunt motor |
| C. | (1)cumulative compound motor (2) shunt motor (3) series motor |
| D. | (1)shunt motor (2) series motor (3) cumulative compound motor |
| Answer» B. (1)cumulative compound motor (2) series motor (3) shunt motor | |
| 63. |
The flux and the internally generated voltage of a dc machine is a                  function of its magneto-motive force. |
| A. | non-linear |
| B. | linear |
| C. | constant |
| D. | inverse |
| Answer» B. linear | |
| 64. |
Second lowest order harmonic present in 3-Φ fully controlled rectifier is |
| A. | 5th |
| B. | 7th |
| C. | 3rd |
| D. | 2nd |
| Answer» C. 3rd | |
| 65. |
Calculate the value of THD if the distortion factor is .8. |
| A. | 76 % |
| B. | 75 % |
| C. | 74 % |
| D. | 73 % |
| Answer» C. 74 % | |
| 66. |
1 Btu/h is equal to |
| A. | .641 |
| B. | .334 |
| C. | .293 |
| D. | .417 |
| Answer» D. .417 | |
| 67. |
Which test is used to determine the conditions where electric motors are being used? |
| A. | thermography |
| B. | geography |
| C. | seismography |
| D. | anthropology |
| Answer» B. geography | |
| 68. |
Calculate the resonant frequency if the values of the capacitor and inductor are 4 F and 4 H. |
| A. | .25 rad/sec |
| B. | .26 rad/sec |
| C. | .28 rad/sec |
| D. | .29 rad/sec |
| Answer» B. .26 rad/sec | |
| 69. |
circuit |
| A. | only the negative cycle can be controlled |
| B. | only the positive cycle can be controlled |
| C. | both the cycles can be controlled |
| D. | none of the mentioned |
| Answer» D. none of the mentioned | |
| 70. |
The below given controller circuit is a |
| A. | half wave controller |
| B. | full wave controller |
| C. | none of the mentioned |
| D. | will depend upon the firing angle |
| Answer» C. none of the mentioned | |
| 71. |
The below shown controller circuit is a |
| A. | half wave controller |
| B. | full wave controller |
| C. | none of the mentioned |
| D. | will depend upon the firing angle |
| Answer» B. full wave controller | |
| 72. |
consists of |
| A. | one scr is parallel with one diode |
| B. | one scr is anti parallel with one diode |
| C. | two scrs in parallel |
| D. | two scrs in anti parallel |
| Answer» C. two scrs in parallel | |
| 73. |
In the principle of phase control |
| A. | the load is on for some cycles and off for some cycles |
| B. | control is achieved by adjusting the firing angle of the devices |
| C. | control is achieved by adjusting the number of on off cycles |
| D. | control cannot be achieved |
| Answer» C. control is achieved by adjusting the number of on off cycles | |
| 74. |
 applications. |
| A. | power generation |
| B. | electric heating |
| C. | conveyor belt motion |
| D. | power transmission |
| Answer» C. conveyor belt motion | |
| 75. |
 devices were used for voltage control applications. |
| A. | cycloconverters |
| B. | vacuum tubes |
| C. | tap changing transformer |
| D. | induction machine |
| Answer» D. induction machine | |
| 76. |
AC voltage controllers convert |
| A. | fixed ac to fixed dc |
| B. | variable ac to variable dc |
| C. | fixed ac to variable ac |
| D. | variable ac to fixed ac |
| Answer» D. variable ac to fixed ac | |
| 77. |
Calculate the total heat dissipated in a resistor of 44 Ω when 0 A current flows through it. |
| A. | 0 w |
| B. | 2 w |
| C. | 1.5 w |
| D. | .3 w |
| Answer» B. 2 w | |
| 78. |
The value of slip at which maximum torque occurs |
| A. | r2÷x2 |
| B. | 4r2÷x2 |
| C. | 2r2÷x2 |
| D. | r2÷3x2 |
| Answer» B. 4r2÷x2 | |
| 79. |
KW. |
| A. | 8 sec |
| B. | 4 sec |
| C. | 7 sec |
| D. | 3 sec |
| Answer» C. 7 sec | |
| 80. |
If induction motor air gap power is 1.8 KW and gross developed power is .1 KW, then |
| A. | s |
| B. | s2 |
| C. | s3 |
| D. | s4 |
| Answer» B. s2 | |
| 81. |
relationship between voltage and current is a straight line. |
| A. | .16 Ω |
| B. | .26 Ω |
| C. | .25 Ω |
| D. | .44 Ω |
| Answer» B. .26 Ω | |
| 82. |
synchronous speed changing technique. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 83. |
phase with the main voltage then speed will |
| A. | increase |
| B. | decrease |
| C. | remain unchanged |
| D. | first increases then decrease |
| Answer» C. remain unchanged | |
| 84. |
Calculate the average value of the sinusoidal waveform x(t)=848sin(1.65πt+2π÷0.68). |
| A. | 0 |
| B. | 78 v |
| C. | 15 v |
| D. | 85 v |
| Answer» B. 78 v | |
| 85. |
The rotor injection method is a part of the slip changing technique. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 86. |
frequency of the rotor current of the motor in Hz is 2. |
| A. | 9.98 |
| B. | 9.71 |
| C. | 9.12 |
| D. | 9.37 |
| Answer» E. | |
| 87. |
R.M.S value of the periodic square waveform of amplitude 72 V. |
| A. | 72 v |
| B. | 56 v |
| C. | 12 v |
| D. | 33 v |
| Answer» B. 56 v | |
| 88. |
an external voltage source is in phase with the main voltage then speed will |
| A. | increase |
| B. | decrease |
| C. | remain unchanged |
| D. | first increases then decrease |
| Answer» B. decrease | |
| 89. |
Calculate the active power in a 788 ω resistor with 178 A current flowing through it. |
| A. | 24.96 mw |
| B. | 24.44 mw |
| C. | 24.12 mw |
| D. | 26.18 mw |
| Answer» B. 24.44 mw | |
| 90. |
Calculate the active power in a 487 H inductor. |
| A. | 2482 w |
| B. | 1545 w |
| C. | 4565 w |
| D. | 0 w |
| Answer» E. | |
| 91. |
rotor? |
| A. | 30 revolution per minute |
| B. | 40 revolution per minute |
| C. | 60 revolution per minute |
| D. | 50 revolution per minute |
| Answer» E. | |
| 92. |
In an induction motor, when the number of stator slots is equal to an integral number of rotor slots |
| A. | there may be a discontinuity in torque slip characteristics |
| B. | a high starting torque will be available |
| C. | the maximum torque will be high |
| D. | the machine may fail to start |
| Answer» E. | |
| 93. |
The slope of the V-I curve is 5°. Calculate the value of resistance. Assume the relationship between voltage and current is a straight line. |
| A. | .3254 Ω |
| B. | .3608 Ω |
| C. | .3543 Ω |
| D. | .3443 Ω |
| Answer» E. | |
| 94. |
The frame of an induction motor is made of |
| A. | aluminum |
| B. | silicon steel |
| C. | cast iron |
| D. | stainless steel |
| Answer» D. stainless steel | |
| 95. |
A 50 Hz, 4poles, a single phase induction motor is rotating in the clockwise direction at a speed of 1425 rpm. The slip of motor in the direction of rotation & opposite direction of the motor will be respectively. |
| A. | 0.05, 0.95 |
| B. | 0.04, 1.96 |
| C. | 0.05, 1.95 |
| D. | 0.05, 0.02 |
| Answer» D. 0.05, 0.02 | |
| 96. |
Calculate the moment of inertia of the thin spherical shell having a mass of 73 kg and diameter of 36 cm. |
| A. | 1.56 kgm2 |
| B. | 1.47 kgm2 |
| C. | 1.38 kgm2 |
| D. | 1.48 kgm2 |
| Answer» B. 1.47 kgm2 | |
| 97. |
Calculate the phase angle of the sinusoidal waveform z(t)=78sin(456πt+2π÷78). |
| A. | π÷39 |
| B. | 2π÷5 |
| C. | π÷74 |
| D. | 2π÷4 |
| Answer» B. 2π÷5 | |
| 98. |
An 8-pole, 3-phase, 50 Hz induction motor is operating at a speed of 720 rpm. The frequency of the rotor current of the motor in Hz is |
| A. | 2 |
| B. | 4 |
| C. | 3 |
| D. | 1 |
| Answer» B. 4 | |
| 99. |
TOPIC 5.1 SPEED CONTROL OF THREE PHASE INDUCTION MOTOR |
| A. | slip frequency |
| B. | supply frequency |
| C. | the frequency corresponding to rotor speed |
| D. | zero |
| Answer» B. supply frequency | |
| 100. |
control method is |
| A. | high initial cost |
| B. | high maintenance cost |
| C. | low efficiency at high loads |
| D. | high cost, high maintenance and low efficiency |
| Answer» E. | |