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.
| 201. |
Braking time in the dynamic braking is the function of |
| A. | system inertia |
| B. | load torque |
| C. | motor rating |
| D. | all- system inertia, load torque and motor rating |
| Answer» E. | |
| 202. |
Which of the following is dynamic braking? |
| A. | reversal of field connections |
| B. | reversal of armature connections |
| C. | addition of equal and opposite field |
| D. | removal of armature circuit from current machine circuit |
| Answer» E. | |
| 203. |
Plugging is used in |
| A. | small motors only |
| B. | small and medium powered |
| C. | only in large heavy machines |
| D. | everywhere |
| Answer» B. small and medium powered | |
| 204. |
Plugging is applied in a motor, if we don’t make the switch OFF what will happen? |
| A. | motor will come to rest as a result of plugging |
| B. | motor will come to rest and will start rotating in another direction |
| C. | motor will burn |
| D. | nothing will happen |
| Answer» C. motor will burn | |
| 205. |
Electrical braking of any variety becomes less effective as |
| A. | speed increases |
| B. | speed decreases |
| C. | independent of speed |
| D. | depends on supply voltage |
| Answer» C. independent of speed | |
| 206. |
Which of the following is correct formula for braking torque in plugging? |
| A. | n (ka2/rb) |
| B. | n2 (ka2/rb) |
| C. | n-1 (ka2/rb) |
| D. | (ka2/rb) |
| Answer» B. n2 (ka2/rb) | |
| 207. |
Which of the following is the plugging method of braking? |
| A. | reversal of field connections |
| B. | reversal of armature connections |
| C. | addition of equal and opposite field |
| D. | removal of field circuit from current machine circuit |
| Answer» C. addition of equal and opposite field | |
| 208. |
Which of the following is not the method of electrical braking? |
| A. | plugging or counter-current |
| B. | dynamic or rheostatic |
| C. | regenerative |
| D. | eddy current |
| Answer» E. | |
| 209. |
DC motor is still widely used in tractions due to its excellent braking properties. |
| A. | true |
| B. | false |
| Answer» C. | |
| 210. |
Which of the following is the best braking method? |
| A. | friction |
| B. | electromechanical action |
| C. | eddy-currents |
| D. | electric braking |
| Answer» E. | |
| 211. |
Choose the correct one. (* stands for multiplication, J represents the moment of inertia, w represents angular speed). |
| A. | j*d(w)/dt = load torque – motor torque |
| B. | j*d(w)/dt = load torque + motor torque |
| C. | j*d(w)/dt = motor torque – load torque |
| D. | j*d(w)/dt = load torque * motor torque |
| Answer» D. j*d(w)/dt = load torque * motor torque | |
| 212. |
What is the condition for the steady-state operation of the motor? |
| A. | load torque > motor torque |
| B. | load torque <<<< motor torque |
| C. | load torque = motor torque |
| D. | load torque < motor torque |
| Answer» D. load torque < motor torque | |
| 213. |
Among the following which one exhibits linearly rising load torque characteristics? |
| A. | elevators |
| B. | rolling mills |
| C. | fan load |
| D. | separately excited dc generator connected to the resistive load |
| Answer» E. | |
| 214. |
Passive torques always oppose the motion of the driven machine. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 215. |
What is the relationship between torque and speed in constant type loads? |
| A. | torque is independent of speed |
| B. | torque linearly increases with increase in speed |
| C. | torque non-linearly increases with an increase in speed |
| D. | torque non-linearly decreases with an increase in speed |
| Answer» B. torque linearly increases with increase in speed | |
| 216. |
What type of force handles for active torques? |
| A. | strong nuclear forces |
| B. | weak nuclear forces |
| C. | gravitational forces |
| D. | electrostatic forces |
| Answer» D. electrostatic forces | |
| 217. |
Torque inversely varies with the speed in the windage load torque component. |
| A. | true |
| B. | false |
| Answer» C. | |
| 218. |
Rolling mills exhibit what type of load torque characteristics? |
| A. | constant torque characteristics |
| B. | linearly rising torque characteristics |
| C. | non-linearly rising torque characteristics |
| D. | non-linearly decreasing torque characteristics |
| Answer» E. | |
| 219. |
b) position, then the |
| A. | motor will draw large current |
| B. | motor will not start |
| C. | motor will burn |
| D. | all of the mentioned |
| Answer» E. | |
| 220. |
many types? |
| A. | three |
| B. | two |
| C. | four |
| D. | five |
| Answer» C. four | |
| 221. |
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 | |
| 222. |
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. | |
| 223. |
It is impossible to start a differential compounded dc motor. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 224. |
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. | |
| 225. |
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 | |
| 226. |
to protect them from dust and contamination. |
| A. | enclosures |
| B. | open environment |
| C. | moisturizing environment |
| D. | hot environment |
| Answer» B. open environment | |
| 227. |
-Φ fully controlled rectifier is |
| A. | 5th |
| B. | 7th |
| C. | 3rd |
| D. | 2nd |
| Answer» C. 3rd | |
| 228. |
Full form of VRF. |
| A. | voltage ripple factor |
| B. | voltage revert factor |
| C. | volume ripple factor |
| D. | volume revert factor |
| Answer» B. voltage revert factor | |
| 229. |
Calculate the value of THD if the |
| A. | 76 % |
| B. | 75 % |
| C. | 74 % |
| D. | 73 % |
| Answer» C. 74 % | |
| 230. |
Calculate the value of Voltage ripple factor if the Form factor is 1.1. |
| A. | 45.8 % |
| B. | 46.2 % |
| C. | 47.5 % |
| D. | 49.9 % |
| Answer» B. 46.2 % | |
| 231. |
Calculate the compensator rating required for a sec(Φ)=1. |
| A. | 0.64 p.u |
| B. | 0.21 p.u |
| C. | 0.57 p.u |
| D. | 0 p.u |
| Answer» E. | |
| 232. |
Full form of THD is |
| A. | total harmonic diverter |
| B. | total harmonic digital |
| C. | total harmonic distortion |
| D. | total harmonic discrete |
| Answer» D. total harmonic discrete | |
| 233. |
Full form of IDMT is |
| A. | inverse definite minimum time |
| B. | inverter definite minimum time |
| C. | inverter definite maximum time |
| D. | insert definite minimum time |
| Answer» B. inverter definite minimum time | |
| 234. |
Overloading can be prevented using |
| A. | over-current protection |
| B. | speed protection |
| C. | over frequency protection |
| D. | oversize protection |
| Answer» B. speed protection | |
| 235. |
The most common cause of motor failure is |
| A. | overloading |
| B. | low resistance |
| C. | contamination |
| D. | over-heating |
| Answer» C. contamination | |
| 236. |
sec. |
| A. | .641 |
| B. | .334 |
| C. | .293 |
| D. | .417 |
| Answer» D. .417 | |
| 237. |
Calculate the heat loss in the electric motor for time interval 0-5 sec using the following data: Ia=2 A, Ra=.8Ω. |
| A. | 16 j-sec |
| B. | 14 j-sec |
| C. | 12 j-sec |
| D. | 10 j-sec |
| Answer» B. 14 j-sec | |
| 238. |
What is the range of size of the motor (kW) for efficiency nearly equals to 90%? |
| A. | 15-150 |
| B. | 0-2 |
| C. | 3-15 |
| D. | 150-250 |
| Answer» B. 0-2 | |
| 239. |
conditions where electric motors are being used? |
| A. | thermography |
| B. | geography |
| C. | seismography |
| D. | anthropology |
| Answer» B. geography | |
| 240. |
Which motor is preferred for overhead traveling cranes? |
| A. | intermittent periodic motor |
| B. | continuous duty motor |
| C. | slow speed duty motor |
| D. | short time rated motor |
| Answer» B. continuous duty motor | |
| 241. |
The direction of the single-phase IM can be reversed by using which one of the method? |
| A. | by interchanging the supply terminals |
| B. | by removing the capacitor |
| C. | by changing the direction of auxiliary winding current |
| D. | by removing the main winding |
| Answer» B. by removing the capacitor | |
| 242. |
motor torque = 2 N-m. |
| A. | 45 rad/s2 |
| B. | the machine will fail to start |
| C. | 30 rad/s2 |
| D. | 51 rad/s2 |
| Answer» C. 30 rad/s2 | |
| 243. |
Calculate the value of the angular acceleration of the Heavy duty crane using the given data: J = 5 kg-m2, load torque = 30 N-m, motor torque = 80 N-m. |
| A. | 10 rad/s2 |
| B. | 20 rad/s2 |
| C. | 30 rad/s2 |
| D. | 50 rad/s2 |
| Answer» B. 20 rad/s2 | |
| 244. |
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 | |
| 245. |
frequency is 2 Hz. |
| A. | 50 hz |
| B. | 49 hz |
| C. | 45 hz |
| D. | 51 hz |
| Answer» B. 49 hz | |
| 246. |
Calculate the frequency of the rotor side of the IM if the value of slip is 0.34 and the supply frequency is 70 Hz. |
| A. | 23.8 hz |
| B. | 22.7 hz |
| C. | 24.5 hz |
| D. | 23.1 hz |
| Answer» B. 22.7 hz | |
| 247. |
1800 second rated motors are used for |
| A. | heavy duty cranes |
| B. | light duty cranes |
| C. | medium duty cranes |
| D. | intermittent duty cranes |
| Answer» D. intermittent duty cranes | |
| 248. |
The capacity of the Crane is expressed in terms of tonnes. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 249. |
Explanation: Intermittent duty cycle has frequent on load and off-loads period. The on-load period and off-loads periods are too |
| A. | frequency changer |
| B. | frequency remover |
| C. | time period remover |
| D. | dc machine |
| Answer» B. frequency remover | |
| 250. |
Which starting method is the worst method in Induction motor? |
| A. | direct online starting |
| B. | autotransformer starting |
| C. | reactance starting |
| D. | star-delta starting |
| Answer» D. star-delta starting | |