electrical engineering Mcqs
1. economics of power generation2. analog electronics3. solid state switching circuits4. parallel circuits5. switchgear and protection6. op amp circuits7. transistor audio power amplifiers8. electrostatics9. heating and welding10. multi stage transistor amplifiers11. passive filters12. network theorems13. regulated d c power supply14. a c fundamentals circuits and circuit theory15. electromagnetic induction16. power electronics17. magnetism and electromagnetism18. transformers19. modulation and demodulation20. d c generators21. semiconductor theory22. single phase induction motors23. semiconductor diode24. hybrid parameters25. digital electronics26. oscillators27. earthing or grounding28. single stage transistor amplifiers29. d c motors30. transistor biasing31. amplifiers with negative feedback32. basic electrical33. electronic instruments34. synchronous motors35. field effect transistors fet36. magnetic circuit37. control systems38. industrial drives39. power generation40. series parallel circuits41. transistor tuned amplifiers42. electrical engineering materials43. rectifiers and converters44. integrated circuits45. scr silicon controlled rectifiers46. cables47. polyphase induction motors48. measurement and instrumentation49. transistors50. electrical machine design51. electrolysis and storage of batteries52. electric traction53. transmission and distribution
251. Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in____________?
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A. transformers having higher copper losses will have negligible core losses

B. short-circuiting of the secondaries

C. loading of the transformers not in proportion to their kVA ratings

D. power factor of one of the transformers is leading while that of the other lagging

252. An instrument which detects electric current is known as_____________?
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A. wattmeter

B. voltmeter

C. galvanometer

D. rheostat

253. If R2 is the resistance of secondary winding of the transformer and K is the transformation ratio then the equivalent secondary resistance referred to primary will be___________?
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A. R2IK2

B. R22/K

C. R2/VK

D. R22!K2

254. Primary winding of a transformer________________?
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A. none of the above

B. could either be a low voltage or high voltage winding

C. is always a low voltage winding

D. is always a high voltage winding

255. Regulator sampling PWM is usually used in___________?
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A. High power inverters

B. Rectifiers

C. Only A. and B.

D. Low power inverters

256. Two lamps 100 W and 40 W are connected in series across 230 V (alternating). Which of the following statement is correct ?
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A. 100 W lamp will glow brighter

B. 40 W lamp will glow brighter

C. Both lamps will glow equally bright

D. 40 W lamp will fuse

257. Conductance : mho :: ____________?
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A. lumen : steradian

B. resistance : ohm

C. capacitance : henry

D. inductance : farad

258. The insulation on a current carrying conductor is provided__________?
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A. to prevent leakage of current

B. to prevent shock

C. both of above factors

D. none of above factors

259. The IGBT resulted in higher switching speed and lower energy losses. It can be used for___________?
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A. Uninterruptible power supplies

B. Constant voltage and frequency power supplies

C. All of these

D. Induction heating system

260. A thermistor has_____________?
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A. positive temperature coefficient

B. negative temperature coefficient

C. zero temperature coefficient

D. variable temperature coefficient

261. No-load current of a transformer has_____________?
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A. has small magnitude and high power factor

B. has small magnitude and low power factor

C. has high magnitude and low power factor

D. has high magnitude and high power factor

262. Two resistances Rl and Ri are connected in series across the voltage source where Rl>Ri. The largest drop will be across______________?
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A. either Rl or Ri

B. Rl

C. Ri

D. none of them

263. What will happen if the transformers working in parallel are not connected with regard to polarity ?
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A. The transformers will not share load in proportion to their kVA ratings

B. none of the above

C. The power factor of the two trans-formers will be different from the power factor of common load

D. Incorrect polarity will result in dead short circuit
264. Noise level test in a transformer is a______________?
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A. special test

B. type test

C. routine test

D. none of the above

265. A field of force can exist only between_____________?
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A. two metal particles

B. two ions

C. two atoms

D. two molecules

266. An electric filament bulb can be worked from____________?
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A. All above

B. D. C. supply only

C. Battery supply only

D. A. C. supply only

267. In a full bridge VSI, in order to avoid the short circuit across the DC bus and the undefined AC output voltage condition, the modulating technique should ensure that___________?
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A. None of these

B. Either A. or B.

C. Top switch of each leg is on at any instant

D. Bottom switch of each leg is on at any instant

268. With gate open, the maximum anode current at which SCR is turned off from ON condition is called____________?
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A. holding current

B. peak reverse voltage

C. breakdown voltage

D. latching current

269. Switching of a lamp in house produces noise in the radio. This is because switching operation produces________?
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A. arcs across separating contacts

B. mechanical noise of high intensity

C. both mechanical noise and arc between contacts

D. none of the above

270. Insulating materials have the function of___________?
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A. storing very high currents

B. conducting very large currents

C. preventing an open circuit between the voltage source and the load

D. preventing a short circuit between conducting wires

271. An open-circuit test on a transformer is conducted primarily to measure______________?
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A. efficiency

B. total loss

C. insulation resistance

D. core loss

E. copper loss

F. none of the above

272. Form factor of a rectifier is the ratio of ______________?
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A. Root mean square value of voltage and current to its average value

B. Root mean square value of voltage and current to its peak value

C. Peak value of current and voltage to its root mean square value

D. Average value of current and voltage to its root mean square value

273. If the firing angle becomes negative, then the rectifier begins to work as_______________?
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A. A chopper

B. A rectifier

C. An inverter

D. A regulator

274. The resistance of a conductor varies inversely as___________?
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A. area of cross-section

B. resistivity

C. length

D. temperature

275. The ac output voltage waveform of VSI and AC output current waveform of CSI respectively is composed of___________?
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A. Low dv / dt, low di / dt

B. High dv / dt, high di / dt

C. Low dv / dt, high di / dt

D. High dv / dt, low di / dt

276. During short circuit test iron losses are negligible because of _____________?
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A. the voltage applied on primary side is low

B. the voltage on secondary side does not vary

C. the current on secondary side is negligible

D. full-load current is not supplied to the transformer

277. If a transformer is continuously operated the maximum temperature rise will occur in_______________?
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A. core

B. tank

C. windings

D. any of the above

278. If a parallel circuit is opened in the main line, the current_______________?
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A. increases in the branch of the lowest resistance

B. is zero in all branches

C. is zero in the highest resistive branch

D. increases in each branch

279. A transformer core is laminated to__________?
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A. reduce eddy current losses

B. reduce copper losses

C. reduce all above losses

D. reduce hysteresis loss

280. Which of the following statement is correct_______________?
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A. A semi-conductor is one which conducts only half of the applied voltage

B. A semi-conductor is a material whose conductivity is same as between that of a conductor and an insulator

C. A semi-conductor is a material made of alternate layers of conducting material and insulator

D. A semi-conductor is a material which has conductivity having average value of conductivity of metal and insulator

281. MOSFET stands for______________?
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A. Metal oxide semiconductor field effect transistor

B. Metal oxide semiconductor field effect transmitter

C. Metal oxide silicon field effect transistor

D. Molybdenum oxide semiconductor field effect transistor

282. The opposite of susceptibility is___________?
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A. Electromagnetic compatibility

B. Immunity

C. Emission

D. Interference

283. A transformer transforms__________________?
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A. current

B. power

C. voltage

D. frequency

284. The use of higher flux density in the transformer design____________?
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A. reduces iron losses

B. increases part load efficiency

C. reduces weight per kVA

D. reduces copper losses

285. Harmonics in transformer result in___________?
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A. all of the above

B. increased core losses

C. magnetic interference with communication circuits

D. increased I2R losses

286. The efficiency of a transformer, under heavy loads, is comparatively low because_______________?
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A. copper loss becomes high in proportion to the output

B. iron loss is increased considerably

C. voltage drop both in primary and secondary becomes large

D. secondary output is much less as compared to primary input

287. Two resistors are said to be connected in series when___________?
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A. same current passes in turn through both

B. both carry the same value of current

C. total current equals the sum of branch currents

D. sum of IR drops equals the applied e.m.f.

288. The full-load copper loss of a transformer is 1600 W. At half-load, the copper loss will be___________?
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A. 800 W

B. 400 W

C. 1600 W

D. 6400 W

289. An open resistor, when checked with an ohm-meter reads_____________?
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A. zero

B. low but not zero

C. infinite

D. high but within tolerance

290. Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds?
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A. 50C

B. 150C

C. 80C

D. 100C

291. The thickness of insulation provided on the conductor depends on_____________?
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A. the magnitude of voltage on the conductor

B. the magnitude of current flowing through it

C. both A. and (b)

D. none of the above

292. A no-load test is performed on a transformer to determine_______________?
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A. core loss

B. copper loss

C. efficiency

D. magnetising current

E. magnetising current and loss
293. Buchholzs relay gives warning and protection against_________________?
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A. electrical fault inside the transformer itself

B. electrical fault outside the transformer in outgoing feeder

C. for both outside and inside faults

D. none of the above

294. For which of the following ampere second could be the unit ?
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A. Power

B. Charge

C. Energy

D. Reluctance

295. To detect an over current fault condition, the most reliable method is to connect a_____________?
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A. Voltage sensor in series with IGBT

B. Current sensor across IGBT

C. Current sensor in series with IGBT

D. Voltage sensor across IGBT

296. The transformer ratings are usually expressed in terms of______________?
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A. kVA

B. kW

C. amperes

D. volts

297. The ratio of mass of proton to that of electron is nearly_____________?
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A. 1840

B. 30

C. 4

D. 1840
298. Greater the secondary leakage flux____________?
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A. less will be the primary terminal voltage

B. none of the above

C. less will be the secondary induced e.m.f.

D. less will be the primary induced e.m.f.

299. If a wire conductor of 0.2 ohm resistance is doubled in length, its resistance becomes______________?
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A. 0.8 ohm

B. 0.4 ohm

C. 0.6 ohm

D. 1.0 ohm

300. are the materials having electrical conductivity much less than most of the metals but much greater than that of typical insulators______________?
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A. Semi-conductors

B. Varistors

C. Thermistor

D. Variable resistors