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MCQOPTIONS
This section includes 354 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.
| 201. |
In a d.c. machine, the form of armature reaction mmf is |
| A. | Triangular |
| B. | Sinusoidal |
| C. | Saw tooth |
| D. | Rectangular |
| Answer» B. Sinusoidal | |
| 202. |
In a d.c. machine, the eddy current losses mainly occurs in |
| A. | Armature |
| B. | Windings |
| C. | Yoke |
| D. | At brush contact |
| Answer» B. Windings | |
| 203. |
In a d.c. machine, the current rating and voltage rating of wave winding is |
| A. | Low, high |
| B. | High, low |
| C. | High, high |
| D. | Low, low |
| Answer» B. High, low | |
| 204. |
In a d.c. machine, the commutator provides |
| A. | Half wave rectification |
| B. | Full wave rectification |
| C. | Semi controlled rectification |
| D. | Uncontrolled rectification |
| Answer» C. Semi controlled rectification | |
| 205. |
In a constant voltage transformer, the primary winding and secondary winding is formed by the |
| A. | capacitor, linear inductor |
| B. | Non linear inductor, capacitor |
| C. | Linear inductor and non linear inductor |
| D. | Capacitor, non linear inductor |
| Answer» D. Capacitor, non linear inductor | |
| 206. |
In a 5 kV / 400V, 75 kVA single phase transformer, the current flowing in the primary winding of transformer is 10A. what will be the current flowing in the secondary winding? |
| A. | 100A |
| B. | 120A |
| C. | 125A |
| D. | 130A |
| Answer» D. 130A | |
| 207. |
In a 4 pole, 3 phase alternator, armature has 40 slots. It is using an armature winding which is short pitched by one slot. Its coil span factor is |
| A. | 0.9 |
| B. | 0.9243 |
| C. | 0.9476 |
| D. | 0.9876 |
| Answer» E. | |
| 208. |
In a 20 kVA, 2200 / 220 volts transformer iron and copper losses are 300 and 400 watts respectively. Its efficiency at half load and unity power factor is |
| A. | 95.11% |
| B. | 96.15% |
| C. | 97.77% |
| D. | 98% |
| Answer» C. 97.77% | |
| 209. |
If x is the order of harmonic component, then the general expression for distribution factor is |
| A. | xsin(β / 2m) / msin(β / 2x) |
| B. | sin(x β /m) / xmsin(m β / 2) |
| C. | sin(xm β / 2) / msin (x β / 2) |
| D. | xmsin(β / 2) /sin(mx β) |
| Answer» D. xmsin(β / 2) /sin(mx β) | |
| 210. |
If W1 is the input power measured by the wattmeter connected across the primaries and W2 is the measurement of wattmeter connected in secondary’s while performing sumpner’s test then iron losses and copper losses is equal to |
| A. | W1, W2 |
| B. | W1 / 2, 2 * W2 |
| C. | 2 * W1, W2 / 2 |
| D. | W1 / 2, W2 / 2 |
| Answer» E. | |
| 211. |
If V1 is the primary applied voltage and E1 is the primary induced emf. For an ideal transformer |
| A. | V1 > E1 |
| B. | V1 = E1 |
| C. | V1 < E1 |
| D. | V1 = E1 / 2 |
| Answer» C. V1 < E1 | |
| 212. |
If two transformers are operated in parallel with voltage ratio of transformer 1 slightly greater than that of 2. E1 and E2 are the induced emf of transformer 1 and 2, and Z1 and Z2 are the impedances then the circulating current is given by |
| A. | (E1-E2) / (Z1+Z2) |
| B. | (E1+E2) / (Z1+Z2) |
| C. | (Z1-Z2) / (E1-E2) |
| D. | (Z1-Z2) / (E1+E2) |
| Answer» B. (E1+E2) / (Z1+Z2) | |
| 213. |
If two mechanically coupled alternators deliver power at 50 Hz and 60 Hz respectively, then the highest speed of alternators will be |
| A. | 1200 rpm |
| B. | 1500 rpm |
| C. | 600 rpm |
| D. | 300 rpm |
| Answer» D. 300 rpm | |
| 214. |
If the voltage supply of a single phase transformer is doubled and the supply frequency is halved, then the eddy current loss will become |
| A. | remains same |
| B. | double of the original |
| C. | four times of original |
| D. | half of the original |
| Answer» D. half of the original | |
| 215. |
If the value of SCR in an alternator is low then the air gap and voltage drop across synchronous reactance will be |
| A. | Low, high |
| B. | High, low |
| C. | Low, low |
| D. | High, high |
| Answer» B. High, low | |
| 216. |
If the transformer is step - up transformer then for performing short circuit test meter is connected to the |
| A. | H.V. side |
| B. | L.V. side |
| C. | Any side |
| D. | Test cannot be performed on step up t / f |
| Answer» B. L.V. side | |
| 217. |
If the transformers have different kVA ratings, then for parallel operation the equivalent impedances should be |
| A. | Directly proportional to individual kVA rating |
| B. | Inversely proportional to individual kVA rating |
| C. | Inversely proportional to the square of the individual kVA rating |
| D. | Directly proportional to the square of individual kVA rating |
| Answer» C. Inversely proportional to the square of the individual kVA rating | |
| 218. |
If the transformation ratio of an autotransformer is given by V2 / V1 then the ratio of power transferred to that of input power is given by |
| A. | (V2-V1) / V1 |
| B. | (V2+V1) / V1 |
| C. | (V1-V2) / V1 |
| D. | V2 / V1 |
| Answer» E. | |
| 219. |
If the supply voltage is kept at constant value and the supply frequency is increased. The magnetizing and core loss component |
| A. | Both will decrease |
| B. | Magnetizing component will increase and core loss will decrease |
| C. | Magnetizing component will decrease and core loss will increase |
| D. | Both will increase |
| Answer» B. Magnetizing component will increase and core loss will decrease | |
| 220. |
If the rotor poles of a 6 pole synchronous generator shift by 8 mechanical degrees from no load to full load, then its torque angle will be |
| A. | 12 degrees |
| B. | 24 degrees |
| C. | 48 degrees |
| D. | 136 degrees |
| Answer» C. 48 degrees | |
| 221. |
If the rotor resistance of an induction motor is doubled, keeping the other parameters constant, then the maximum torque of the induction motor will become |
| A. | Double |
| B. | Halved |
| C. | One fourth |
| D. | Remains same |
| Answer» E. | |
| 222. |
If the rotor of the machine catches the speed of the rotating magnetic field, then the motor will |
| A. | Rotate at the speed of rotating magnetic field |
| B. | Rotate at double the speed of the rotating magnetic field |
| C. | Eventually stop |
| D. | None of these |
| Answer» D. None of these | |
| 223. |
If the primary winding is excited by a purely sinusoidal alternating voltage, than the nature of the flux produced is |
| A. | Square wave |
| B. | Rectangular wave |
| C. | Saw tooth wave |
| D. | Sinusoidal wave |
| Answer» E. | |
| 224. |
If the power factor of load is near unity and leading, the full load voltage regulation of a power transformer will be |
| A. | Zero |
| B. | One |
| C. | 0.5 |
| D. | 0.707 |
| Answer» B. One | |
| 225. |
If the power factor of a transformer increases, then its efficiency will |
| A. | Increases |
| B. | Decreases |
| C. | Remains constant |
| D. | Not related to each other |
| Answer» B. Decreases | |
| 226. |
If the no load speed of d.c. motor is 1350 rpm and full load speed is 1150 rpm, then its voltage regulation is |
| A. | 11.56 % |
| B. | 15.36 % |
| C. | 17.39 % |
| D. | 19.39 % |
| Answer» D. 19.39 % | |
| 227. |
If the magnitude of leakage reactance is equal to the resistance of both primary and secondary of a single phase transformer. Then the input power factor is |
| A. | 1 / √2 |
| B. | 1 |
| C. | √2 |
| D. | zero |
| Answer» B. 1 | |
| 228. |
If the load on a synchronous motor increases then its |
| A. | Current drawn by motor increases and load angle decreases |
| B. | Current drawn by motor decreases and load angle remains constant |
| C. | Current drawn by motor remains constant and load angle increases |
| D. | Current drawn by motor increases and load angle also increases |
| Answer» E. | |
| 229. |
If the load connected to the alternator are having zero leading power factor and zero lagging power factor, then the nature of load in each case will be |
| A. | Inductive, capacitive |
| B. | Inductive, inductive |
| C. | Capacitive, capacitive |
| D. | Capacitive, inductive |
| Answer» E. | |
| 230. |
If the frequency of a three phase induction motor is doubled and number of poles is halved, then its synchronous speed is given by |
| A. | Remains same |
| B. | Becomes double of the original synchronous speed |
| C. | Becomes four times of the original synchronous speed |
| D. | Becomes half of the original synchronous speed |
| Answer» D. Becomes half of the original synchronous speed | |
| 231. |
If the frequencies of the two alternators in lamp dark method for synchronization of alternators are unequal, then the two lamps will |
| A. | Glow together |
| B. | Become alternately bright and dark |
| C. | Not glow at all |
| D. | None of the above |
| Answer» C. Not glow at all | |
| 232. |
If the flux is increased by 50% and speed is reduced by 50% of a d.c. motor (keeping the other parameters constant), then its back emf will become |
| A. | 50 % of the original back emf |
| B. | 0.75 % of the original back emf |
| C. | 100 % of the original back emf |
| D. | 150 % of the original back emf |
| Answer» C. 100 % of the original back emf | |
| 233. |
If the field of the synchronous motor is overexcited then its power factor will be |
| A. | Lagging |
| B. | Leading |
| C. | Unity |
| D. | Zero |
| Answer» C. Unity | |
| 234. |
If the back emf of a d.c. motor is doubled and flux is halved (keeping other parameters constant) then its speed will become |
| A. | Double of the original speed |
| B. | Square of the original speed |
| C. | Four times of the original speed |
| D. | Half of the original speed |
| Answer» D. Half of the original speed | |
| 235. |
If the armature resistance and synchronous reactance of a 2 MVA, 11 kV, 3 phase star connected alternator are 2 ohm and 20 ohm per phase respectively. The value of full load generated voltage per phase at unity power factor will be |
| A. | 6888.45 V |
| B. | 6899.65 V |
| C. | 6999.45 V |
| D. | 7111.45 V |
| Answer» B. 6899.65 V | |
| 236. |
If the applied voltage is increased by 10% and the applied frequency is increased by 20% of a single phase transformer, the percentage change in eddy current losses will be |
| A. | 19% |
| B. | 20% |
| C. | 21% |
| D. | 40% |
| Answer» D. 40% | |
| 237. |
If the applied voltage of a certain transformer is increased by 50% keeping the frequency constant, the maximum flux density will become |
| A. | Remains same |
| B. | 1.5 times the original value |
| C. | Double the original value |
| D. | Half of the original value |
| Answer» C. Double the original value | |
| 238. |
If the air gap of the induction motor increases then its power factor |
| A. | Increase |
| B. | Decreases |
| C. | Remains same |
| D. | Either increases or decreases |
| Answer» C. Remains same | |
| 239. |
If short circuit test is performed on the transformer with constant rated voltage and increased frequency, then the short circuit current and power factor |
| A. | Both will increase |
| B. | Both will decrease |
| C. | Increase, decrease |
| D. | Decrease, remains constant |
| Answer» C. Increase, decrease | |
| 240. |
If K is the transformation ratio, then the secondary phase voltage of delta-delta connected three phase transformer will be |
| A. | 1 / K times of the primary phase voltage |
| B. | Equal to the primary phase voltage |
| C. | 1 / K ∧ 2 times of the primary phase voltage |
| D. | K times the primary phase voltage |
| Answer» E. | |
| 241. |
If in the d.c machine, the reversal of current in the coil is faster than ideal or linear commutation then the commutation is said to be |
| A. | Retarded commutation |
| B. | Under commutation |
| C. | Accelerated commutation |
| D. | Ideal commutation |
| Answer» D. Ideal commutation | |
| 242. |
If graph of armature current drawn by synchronous motor is against field current is plotted then the resulted graph is known as |
| A. | V-curves |
| B. | Inverted V-curves |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» B. Inverted V-curves | |
| 243. |
If coil side in one slot is connected to a coil side in another slot which is one pole pitch distance away from first slot, the winding is said to be |
| A. | Short pitched |
| B. | Full pitched |
| C. | Concentrated |
| D. | Distributed |
| Answer» C. Concentrated | |
| 244. |
If an induction motor is operating at a point in the high slip region, then the motor will be |
| A. | Stable |
| B. | Unstable |
| C. | Either stable or unstable depending on the torque |
| D. | None of these |
| Answer» C. Either stable or unstable depending on the torque | |
| 245. |
If an autotransformer having transformation ratio equal to 0.6 is supplying a load of 8kw then its power transferred from primary to secondary is given by |
| A. | 3 kW |
| B. | 3.2 kW |
| C. | 3.4 kW |
| D. | 3.5 kW |
| Answer» C. 3.4 kW | |
| 246. |
If a voltmeter when connected to the rotor of an induction motor gives 150 oscillations per minute and stator frequency is 50 Hz. Then the slip of induction motor will be |
| A. | 3% |
| B. | 4.5% |
| C. | 5% |
| D. | 5.5% |
| Answer» D. 5.5% | |
| 247. |
If a two winding transformer is converted into an autotransformer by applying additive polarity and subtractive polarity which results in the secondary voltages of 1840 and 1810 volts. Then the primary and secondary voltages of transformer are |
| A. | 1800V, 50V |
| B. | 1810V, 40V |
| C. | 1820V, 30V |
| D. | 1825V, 15V |
| Answer» E. | |
| 248. |
If a three phase winding is displaced in space by 120 degree in a synchronous motor then the magnitude of resultant flux when it is rotated by Θ = 0 degree and Θ = 60 degree is |
| A. | 0, 1.5 times the magnitude of maximum flux |
| B. | 1.5 times the magnitude of maximum flux, 0 |
| C. | 0.866 times the magnitude of maximum flux, 1.5 times the magnitude of maximum flux |
| D. | 1.5 times the magnitude of maximum flux, 1.5 times the magnitude of maximum flux |
| Answer» E. | |
| 249. |
If a shunt motor is started with its field winding open then |
| A. | It will rotate at the same speed as that with its field winding closed |
| B. | It will rotate at less speed as that with its field winding closed |
| C. | It will rotate at dangerously high speed |
| D. | None of these |
| Answer» D. None of these | |
| 250. |
If a resistance is added in series with the field winding of d.c. shunt motor, then its |
| A. | Both speed and torque decreases |
| B. | Both speed and torque increases |
| C. | Speed decreases, torque increases |
| D. | Speed increases, torque decreases |
| Answer» E. | |