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.
| 151. |
is |
| A. | main field distortion |
| B. | shift in mna |
| C. | reduction in main field |
| D. | none of the mentioned |
| Answer» E. | |
| 152. |
The effect of fringing increases as we |
| A. | increase air gap |
| B. | decrease air gap |
| C. | increase in flux density |
| D. | introduce more ferric core material |
| Answer» B. decrease air gap | |
| 153. |
over DOL starter due to |
| A. | lesser losses |
| B. | controlled direction |
| C. | least resistance offered |
| D. | all of the mentioned |
| Answer» B. controlled direction | |
| 154. |
The direct-on-line starter is used to start a small dc motor because it limits initial current drawn by armature circuit. |
| A. | true |
| B. | false |
| Answer» C. | |
| 155. |
full load efficiency of 85% has armature resistance of 0.25 ohms. Calculate the value of starting resistance in ohms for a current 1.5 times of the full load current. |
| A. | 2.788 |
| B. | 3.038 |
| C. | 2.688 |
| D. | 2.588 |
| Answer» B. 3.038 | |
| 156. |
is/are |
| A. | 3-point and 4-point starter |
| B. | 5-point starter |
| C. | 4-point starter |
| D. | 5-point and 3-point starter |
| Answer» B. 5-point starter | |
| 157. |
(iv) Burning of the field winding |
| A. | (i), (ii), (iii), (iv) |
| B. | (i), (iii) |
| C. | (ii), (iii), (iv) |
| D. | (i), (ii) |
| Answer» B. (i), (iii) | |
| 158. |
b) |
| A. | starting resistance would burn |
| B. | field winding would burn |
| C. | speed will rise steeply |
| D. | any of the mentioned |
| Answer» B. field winding would burn | |
| 159. |
A 100 hp, 250 V, 350 A shunt dc motor with an armature resistance of 0.05 ohms. To limit maximum starting current to twice the rated of its value, what will be the number of stages of starting resistances? |
| A. | 3 |
| B. | 2 |
| C. | 4 |
| D. | 5 |
| Answer» B. 2 | |
| 160. |
starting in an induction motor as well as dc motor. |
| A. | induction motor has to control starting torque whereas in dc motor, it is done to avoid large current |
| B. | to limit starting current in both the machines |
| C. | to limit starting speed |
| D. | all of the mentioned |
| Answer» B. to limit starting current in both the machines | |
| 161. |
Four-point starter is used when |
| A. | motor field current is varied in narrow range |
| B. | motor speed is varied in small range |
| C. | motor field current is varied over wide range |
| D. | can be used anywhere |
| Answer» D. can be used anywhere | |
| 162. |
γ is given as 1.585. Resistance at maximum allowable current is given equal to 4 Ω, what is the 5th step resistance? |
| A. | 0.235 |
| B. | 0.370 |
| C. | 1.476 |
| D. | 2 |
| Answer» B. 0.370 | |
| 163. |
motor. The maximum allowable current is 55 A and the minimum current is about 35 A. The armature resistance of the motor is 0.4 Ω. What will be the number of sections of starter resistance required? |
| A. | 5 |
| B. | 4 |
| C. | 6 |
| D. | 8 |
| Answer» D. 8 | |
| 164. |
In shunt and compound motor starting the shunt field should be made on with full starting resistance in |
| A. | series with field |
| B. | parallel with field |
| C. | series with armature |
| D. | parallel with armature |
| Answer» D. parallel with armature | |
| 165. |
Motor will start quickly when used without starter. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 166. |
without starter? |
| A. | heavy sparking at brushes |
| B. | it’ll start smoothly |
| C. | will not start at all |
| D. | depends on load |
| Answer» B. it’ll start smoothly | |
| 167. |
The starting resistance of a DC shunt motor is generally |
| A. | low |
| B. | around 0.5 kΩ |
| C. | around 5 kΩ |
| D. | infinitely large |
| Answer» B. around 0.5 kΩ | |
| 168. |
A three-point starter is used for |
| A. | shunt motors |
| B. | shunt as well as compound motors |
| C. | shunt, compound and series motors |
| D. | not for dc motors |
| Answer» C. shunt, compound and series motors | |
| 169. |
For which motors DOL starter can be used? |
| A. | up to 5 h.p |
| B. | up to 10 h.p |
| C. | up to 15 h.p |
| D. | up to 20 h.p |
| Answer» B. up to 10 h.p | |
| 170. |
Why starters are required in a DC motor? |
| A. | back emf of these motors is zero initially |
| B. | these motors are not self-starting |
| C. | these motors have high starting torque |
| D. | to restrict armature current as there is no back emf at starting |
| Answer» E. | |
| 171. |
What is the range of the power factor of electrolytic capacitors? |
| A. | 2-4 |
| B. | 4-6 |
| C. | 6-8 |
| D. | 7-9 |
| Answer» D. 7-9 | |
| 172. |
The electrolytic capacitor and insulator unit is impregnated using ethylene glycol or a derivative. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 173. |
The ac electrolytic capacitor is formed by winding two sheets of etched aluminium foil. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 174. |
What type of operations are used in the starting switches? |
| A. | mechanical operation |
| B. | electrical operation |
| C. | centrifugal operation and mechanical operation |
| D. | centrifugal operation |
| Answer» D. centrifugal operation | |
| 175. |
What material is used in the tunnel of the rotor of the single phase induction motor? |
| A. | aluminium |
| B. | copper |
| C. | steel |
| D. | wood |
| Answer» B. copper | |
| 176. |
What is/are the advantages of the skein winding? |
| A. | low cost to wind |
| B. | low cost to insert |
| C. | permits some freedom of choice of distribution |
| D. | low cost to wind, low cost to insert, permits some freedom of choice of distribution |
| Answer» E. | |
| 177. |
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 | |
| 178. |
Which winding is mostly used winding in the single phase induction motor? |
| A. | circular winding |
| B. | concentric winding |
| C. | progressive winding |
| D. | skein winding |
| Answer» C. progressive winding | |
| 179. |
When is the skein winding made use of? |
| A. | when small amount of relatively small size wire is used |
| B. | when large amount of relatively small size wire is used |
| C. | when large amount of relatively large size wire is used |
| D. | when small amount of relatively large size wire is used |
| Answer» B. when large amount of relatively small size wire is used | |
| 180. |
What is the form of the progressive windings? |
| A. | double layer diamond coil windings |
| B. | single layer diamond coil windings |
| C. | multi layer diamond coil windings |
| D. | three layer diamond coil windings |
| Answer» C. multi layer diamond coil windings | |
| 181. |
How are the poles and pitches in the concentric windings? |
| A. | single pole, different pitches |
| B. | different pole, different pitches |
| C. | different pole, single pitch |
| D. | single pole, single pitch |
| Answer» B. different pole, different pitches | |
| 182. |
How many kinds of single phase windings are present? |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 5 |
| Answer» C. 4 | |
| 183. |
What type of coils are used for winding the single phase induction motor generally? |
| A. | rectangular coils |
| B. | square coils |
| C. | cruciform coils |
| D. | circular coils |
| Answer» E. | |
| 184. |
What is the lamination used for the stator? |
| A. | cast iron |
| B. | die cast aluminium alloy frame |
| C. | cast iron or die cast aluminium alloy frame |
| D. | cast iron and die cast aluminium alloy frame |
| Answer» D. cast iron and die cast aluminium alloy frame | |
| 185. |
construction of single phase induction motor? |
| A. | 3 |
| B. | 4 |
| C. | 5 |
| D. | 6 |
| Answer» D. 6 | |
| 186. |
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. | |
| 187. |
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 | |
| 188. |
Sometimes motor has to be de-rated. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 189. |
Sparking is discouraged in a DC motor. |
| A. | true |
| B. | false |
| Answer» C. | |
| 190. |
In which of the following case we will get maximum power? |
| A. | ea = 2 x supply voltage |
| B. | ea = supply voltage |
| C. | supply voltage = 2 x ea |
| D. | supply voltage = 4 x ea |
| Answer» D. supply voltage = 4 x ea | |
| 191. |
An electric motor is having constant output power. So, motor will have a torque speed characteristic |
| A. | circle about the origin. |
| B. | straight line parallel to the speed axis. |
| C. | straight line through the origin. |
| D. | rectangular hyperbola |
| Answer» E. | |
| 192. |
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. | |
| 193. |
Direction of rotation of motor is determined by |
| A. | faraday’s law |
| B. | lenz’s law |
| C. | coulomb’s law |
| D. | fleming’s left-hand rule |
| Answer» E. | |
| 194. |
can sustain the maximum temperature rise? |
| A. | field winding |
| B. | commutator |
| C. | slip rings |
| D. | armature winding |
| Answer» B. commutator | |
| 195. |
is DC motor and not an AC type? |
| A. | winding |
| B. | shaft |
| C. | commutator |
| D. | stator |
| Answer» D. stator | |
| 196. |
What will happen, with the increase in speed of a DC motor? |
| A. | back emf increase but line current falls. |
| B. | back emf falls and line current increase. |
| C. | both back emf as well as line current increase. |
| D. | both back emf as well as line current fall. |
| Answer» B. back emf falls and line current increase. | |
| 197. |
What will happen if the back emf of a DC motor vanishes suddenly? |
| A. | the motor will stop |
| B. | the motor will continue to run |
| C. | the armature may burn |
| D. | the motor will run noisy |
| Answer» D. the motor will run noisy | |
| 198. |
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. | |
| 199. |
In which of the following electrical braking method, energy is supplied back to the supply? |
| A. | plugging |
| B. | dynamic braking |
| C. | regenerative braking |
| D. | in all electrical braking |
| Answer» D. in all electrical braking | |
| 200. |
In dynamic braking, when braking is applied system acts as |
| A. | freely running machine |
| B. | motor with slow speed |
| C. | generator |
| D. | motor with same speed in opposite direction |
| Answer» D. motor with same speed in opposite direction | |