McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 251. |
Calculate the moment of inertia of the disc having a mass of 54 kg and diameter of 91 cm. |
| A. | 5.512 kgm2 |
| B. | 5.589 kgm2 |
| C. | 5.487 kgm2 |
| D. | 5.018 kgm2 |
| Answer» B. 5.589 kgm2 | |
| 252. |
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» D. the machine may fail to start | |
| 253. |
In the rotor voltage injection method, when 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» A. increase | |
| 254. |
A 2-pole, 3-phase, Hz induction motor is operating at a speed of 550 rpm. The 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» D. 9.37 | |
| 255. |
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» A. 0 | |
| 256. |
In the rotor voltage injection method, when an external voltage source is in opposite phase with the main voltage then speed will |
| A. | increase |
| B. | decrease |
| C. | remain unchanged |
| D. | first increases then decrease |
| Answer» B. decrease | |
| 257. |
The slip recovery scheme is a part of the synchronous speed changing technique. |
| A. | true |
| B. | false |
| Answer» A. true | |
| 258. |
If induction motor air gap power is 1.8 KW and gross developed power is .1 KW, then rotor ohmic loss will be KW. |
| A. | 1.7 |
| B. | 2.7 |
| C. | 3.7 |
| D. | 4.7 |
| Answer» A. 1.7 | |
| 259. |
Calculate the time period of the waveform v(t)=12sin(8πt+8π÷15)+144sin(2πt+π÷6)+ 445sin(πt+7π÷6). |
| A. | 8 sec |
| B. | 4 sec |
| C. | 7 sec |
| D. | 3 sec |
| Answer» B. 4 sec | |
| 260. |
The value of slip at which maximum torque occurs |
| A. | r2÷x2 |
| B. | 4r2÷x2 |
| C. | 2r2÷x2 |
| D. | r2÷3x2 |
| Answer» A. r2÷x2 | |
| 261. |
In AC voltage controllers the |
| A. | variable ac with fixed frequency is obtained |
| B. | variable ac with variable frequency is obtained |
| C. | variable dc with fixed frequency is obtained |
| D. | variable dc with variable frequency is obtained |
| Answer» A. variable ac with fixed frequency is obtained | |
| 262. |
A single-phase half wave voltage controller 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» B. one scr is anti parallel with one diode | |
| 263. |
In the below given voltage controller circuit |
| A. | the positive half cycle at the load is same as the supply vs |
| B. | the negative half cycle at the load is same as the supply vs |
| C. | the positive and negative half cycles at the load are identical to the supply |
| D. | none of the mentioned |
| Answer» B. the negative half cycle at the load is same as the supply vs | |
| 264. |
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» A. half wave controller | |
| 265. |
In the below given voltage controller 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» C. both the cycles can be controlled | |
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