MCQOPTIONS
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MCQOPTIONS
This section includes 240 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
*/*_In a hysteresis motor, the rotor must have? |
| A. | retentivity |
| B. | resistivity |
| C. | susceptibility |
| D. | none of the above |
| Answer» B. resistivity | |
| 152. |
*/*_Centrifugal switch disconnects the auxiliary winding of the motor at about ____ percent of synchronous speed? |
| A. | 30 to 40 |
| B. | 70 to 80 |
| C. | 80 to 90 |
| D. | 100 |
| Answer» C. 80 to 90 | |
| 153. |
*/*_Which of the following motors is used in mixies ?? |
| A. | Repulsion motor |
| B. | Reluctance motor |
| C. | Hysteresis motor |
| D. | Universal motor |
| Answer» E. | |
| 154. |
*/*_In A.C. series motor compensating winding is employed to? |
| A. | reduce the effects of armature reaction |
| B. | increase the torque |
| C. | reduce sparking at the brushes |
| D. | none of the above |
| Answer» D. none of the above | |
| 155. |
*/*_In which single-phase motor, the rotor has no teeth or winding ?? |
| A. | Split phase motor |
| B. | Reluctance motor |
| C. | Hysteresis motor |
| D. | Universal motor |
| Answer» D. Universal motor | |
| 156. |
_ Which of the following single-phase motors has relatively poor starting torque ?$? |
| A. | Universal motor |
| B. | Repulsion motor |
| C. | Capacitor motor |
| D. | All single phase motors have zero starting torque |
| Answer» D. All single phase motors have zero starting torque | |
| 157. |
_ If a particular application needs high speed and high starting torque, then which of the following motor will bepreferred ?$? |
| A. | Universal motor |
| B. | Shaded pole type motor |
| C. | Capacitor start motor |
| D. | Capacitor start and run motor |
| Answer» B. Shaded pole type motor | |
| 158. |
_ If the capacitor of a single-phase motor is short-circuited$? |
| A. | the motor will not start |
| B. | the motor will run |
| C. | the motor will run in reverse direction |
| D. | the motor will run in the same direction at reduced r.p.m. |
| Answer» B. the motor will run | |
| 159. |
_ The rotor slots, in an induction motor, are usually not quite parallel to the shaft because it$? |
| A. | improves the efficiency |
| B. | helps the rotor teeth to remain under the stator teeth |
| C. | helps in reducing the tendency of the rotor teeth to remain under the stator teeth |
| D. | improves the power factor |
| Answer» D. improves the power factor | |
| 160. |
_ In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will$? |
| A. | Become unstable |
| B. | Draw excessive armature current and may burn out |
| C. | Fall out of synchronism and come to stand still |
| D. | Run as induction motor |
| Answer» E. | |
| 161. |
_ In repulsion motor, maximum torque is developed when$? |
| A. | brush axis is at 45° electrical to the field axis |
| B. | brush axis coincides with the field axis |
| C. | brush axis is at 90° electrical to the field axis |
| D. | none of the above |
| Answer» B. brush axis coincides with the field axis | |
| 162. |
_ In which single-phase motor, the rotor has no teeth or winding ?$? |
| A. | Split phase motor |
| B. | Reluctance motor |
| C. | Hysteresis motor |
| D. | Universal motor |
| Answer» D. Universal motor | |
| 163. |
_ In A.C. series motor compensating winding is employed to$? |
| A. | reduce the effects of armature reaction |
| B. | increase the torque |
| C. | reduce sparking at the brushes |
| D. | none of the above |
| Answer» D. none of the above | |
| 164. |
_ Speed control of a universal motor is achieved by$? |
| A. | Varying field flux with tapped field windings |
| B. | Connecting rheostat in series |
| C. | Applying variable voltage by means of silicon controlled rectifier |
| D. | All of the above methods |
| Answer» E. | |
| 165. |
_ The motor used on small lathes is usually$? |
| A. | universal motor |
| B. | D.C. shunt motor |
| C. | single-phase capacitor run motor |
| D. | 3-phase synchronous motor |
| Answer» D. 3-phase synchronous motor | |
| 166. |
_ To reverse the direction of rotation of acapacitor start motor while it is running we should$? |
| A. | disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of main or auxiliary winding |
| B. | disconnect motor from supply and immediately reconnect it to supply with reversed con-nections of the main winding |
| C. | reverse the direction of connection of the auxiliary winding and after motor comes to rest then connect auxiliary winding to the supply |
| D. | reverse the direction of connections of the auxiliary winding and immediately connect it to supply |
| Answer» B. disconnect motor from supply and immediately reconnect it to supply with reversed con-nections of the main winding | |
| 167. |
_ Which of the following single-phase induction motors is generally used in time phonographs?$? |
| A. | Resistance start |
| B. | Capacitor start capacitor run |
| C. | Shaded pole |
| D. | Universal |
| Answer» D. Universal | |
| 168. |
_ Which of the following motor will give relatively high starting torque ?$? |
| A. | Capacitor start motor |
| B. | Capacitor run motor |
| C. | Split phase motor |
| D. | Shaded pole motor |
| Answer» B. Capacitor run motor | |
| 169. |
_ Which of the following applications always have some load whenever switched on ?$? |
| A. | Vacuum cleaners |
| B. | Fan motors |
| C. | Pistol drills |
| D. | All of the above |
| Answer» D. All of the above | |
| 170. |
_ In a single phase motor the centrifugal switch$? |
| A. | disconnects auxiliary winding of the motor |
| B. | disconnects main winding of the motor |
| C. | reconnects the main winding the motor |
| D. | reconnects the auxiliary winding of the motor |
| Answer» B. disconnects main winding of the motor | |
| 171. |
_ Two-value capacitor motor finds increased application as compressor motor in small home air-conditioners because$? |
| A. | it is comparatively cheaper |
| B. | it has almost non-destructible capacitor |
| C. | it has low starting as well as running currents at relatively high power factor |
| D. | it is quiet in operation |
| Answer» D. it is quiet in operation | |
| 172. |
_ Which motor is normally free from mechanical and magnetic vibrations ?$? |
| A. | Split phase motor |
| B. | Universal motor |
| C. | Hysteresis motor |
| D. | Shaded pole motor |
| Answer» D. Shaded pole motor | |
| 173. |
_ In capacitor start single-phase motors$? |
| A. | current in the starting winding leads the voltage |
| B. | current in the starting winding lags the voltage |
| C. | current in the starting winding is in phase with voltage in running winding |
| D. | none of the above |
| Answer» B. current in the starting winding lags the voltage | |
| 174. |
_ In repulsion motor direction of rotation of motor$? |
| A. | is opposite to that of brush shift |
| B. | is the same as that of brush shift |
| C. | is independent of brush shift |
| Answer» C. is independent of brush shift | |
| 175. |
_ Which of the following motors is preferred for tape-recorders?$? |
| A. | Shaded pole motor |
| B. | Hysteresis motor |
| C. | Two value capacitor motor |
| D. | Universal motor |
| Answer» C. Two value capacitor motor | |
| 176. |
Which of the following statements regarding hysteresis motor is in incorrect ?$? |
| A. | It is extremely sensitive to fluctuations in supply voltage |
| B. | Its high starting torque is due to its high rotor hysteresis loss |
| C. | It is extremely quiet in operation |
| D. | It accelerates from rest to full-speed almost instantaneously |
| Answer» B. Its high starting torque is due to its high rotor hysteresis loss | |
| 177. |
The motor used for the compressors is$? |
| A. | d.c. series motor |
| B. | shaded pole motor |
| C. | capacitor-start capacitor-run motor |
| D. | reluctance motor |
| Answer» D. reluctance motor | |
| 178. |
The speed/load characteristics of a universal motor is same as that of$? |
| A. | D.C. motor |
| B. | D.C. shunt motor |
| C. | D.C. series motor |
| D. | none of the above |
| Answer» D. none of the above | |
| 179. |
If starting winding of a single-phase induction motor is left in the circuit, it will$? |
| A. | run faster |
| B. | spark at light loads |
| C. | draw excessive current and overheat |
| D. | run slower |
| Answer» D. run slower | |
| 180. |
The rotor of a hysteresis motor is made of$? |
| A. | aluminium |
| B. | cast iron |
| C. | chrome steel |
| D. | copper |
| Answer» D. copper | |
| 181. |
A repulsion motor is equipped with$? |
| A. | slip rings |
| B. | commutator |
| C. | both (A) and (B) |
| D. | none of the above |
| Answer» C. both (A) and (B) | |
| 182. |
Which of the following motors is inherently self starting ?$? |
| A. | Split motor |
| B. | Shaded-pole motor |
| C. | Reluctance motor |
| D. | None of these |
| Answer» C. Reluctance motor | |
| 183. |
The electric motor used in portable drills is$? |
| A. | capacitor run motor |
| B. | hysteresis motor |
| C. | universal motor |
| D. | repulsion motor |
| Answer» D. repulsion motor | |
| 184. |
Torque developed by a single phase induction motor at starting is$? |
| A. | pulsating |
| B. | uniform |
| C. | none of the above |
| D. | nil |
| Answer» E. | |
| 185. |
When a D.C. series motor is connected to A.C. supply, the power factor will be low because of$? |
| A. | high inductance of field and armature circuits |
| B. | induced current in rotor due to variations of flux |
| C. | fine copper wire winding |
| D. | none of the above |
| Answer» B. induced current in rotor due to variations of flux | |
| 186. |
Starting winding of a single phase motor of a refrigerator is disconnected from the circuit by means of a$? |
| A. | Magnetic relay |
| B. | Thermal relay |
| C. | Centrifugal switch |
| D. | None of the above |
| Answer» B. Thermal relay | |
| 187. |
In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to$? |
| A. | improve power factor |
| B. | increase overload capacity |
| C. | reduce fluctuations in torque |
| D. | to improve torque |
| Answer» B. increase overload capacity | |
| 188. |
The running winding of a single phase motor on testing with Meggar is found to be ground. Most probable location of the ground will be$? |
| A. | At the end connections |
| B. | At the end terminals |
| C. | Anywhere on the winding inside a slot |
| D. | At the slot edge where coil enters or comes out of the slot |
| Answer» E. | |
| 189. |
Which of the following motors can be run on AC. as well as D.C. supply ?$? |
| A. | Universal motor |
| B. | Repulsion motor |
| C. | Synchronous motor |
| D. | Reluctance motor |
| Answer» B. Repulsion motor | |
| 190. |
Which of the following motors has two separate windings on the motor ?$? |
| A. | Repulsion motor |
| B. | Repulsion induction motor |
| C. | Repulsion start induction run motor |
| D. | None of the above |
| Answer» C. Repulsion start induction run motor | |
| 191. |
The capacitors used in single-phase capacitor motors have no$? |
| A. | voltage rating |
| B. | dielectric medium |
| C. | polarity marking |
| D. | definite value |
| Answer» D. definite value | |
| 192. |
A schrage motor can run on$? |
| A. | zero slip |
| B. | negative slip |
| C. | positive slip |
| D. | all of the above |
| Answer» E. | |
| 193. |
In a two value capacitor motor, the capacitor used for running purposes is$? |
| A. | air capacitor |
| B. | paper spaced oil filled type |
| C. | ceramic type |
| D. | a.c. electrolytic type |
| Answer» C. ceramic type | |
| 194. |
In a universal motor, the most common cause of brush sparking is$? |
| A. | open armature winding |
| B. | shorted armature winding |
| C. | shorted field winding? |
| D. | high commutator mica |
| E. | all of the above |
| Answer» F. | |
| 195. |
Which type of load is offered by cranes and hoists ?$? |
| A. | Gradually varying load |
| B. | Non-reversing, no-load start |
| C. | Reversing, light start |
| D. | Reversing, heavy start |
| Answer» E. | |
| 196. |
Which of the following statements regarding single-phase induction motoris correct ? |
| A. | It requires only one winding |
| B. | It can rotate in one direction only |
| C. | It is self-starting |
| D. | It is not self-starting |
| Answer» E. | |
| 197. |
Most of the fractional horsepower motors have either |
| A. | hard and annealed bearings |
| B. | ball or roller bearings |
| C. | soft and porous bearings |
| D. | plain or sleeve bearings |
| Answer» E. | |
| 198. |
Hysteresis motor is particularly useful for high-quality record players and tape-recorders because |
| A. | it revolves synchronously |
| B. | it is not subject to any magnetic or mechanical vibrations |
| C. | it can be easily manufactured in extremely small sizes of up to 1 W output |
| D. | it develops hysteresis torque which is extremely steady both in amplitude and phase |
| Answer» E. | |
| 199. |
A capacitor-start single phase induction motor is switched on to supply with its capa-citor replaced by an inductor of equivalent reactance value. It will |
| A. | start and then stop |
| B. | start and run slowly |
| C. | start and run at rated speed |
| D. | not start at all |
| Answer» E. | |
| 200. |
Locked rotor current of a shaded pole motor is |
| A. | equal to full load current |
| B. | less than full load current |
| C. | slightly more than full load current |
| D. | several times the full load current |
| Answer» D. several times the full load current | |