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
351. Which of the following is the most likely source of harmonics in a transformer ?
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A. Overload

B. Core saturation

C. poor insulation

D. loose connections

352. Electric current passing through the circuit produces_____________?
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A. magnetic effect

B. luminous effect

C. chemical effect

D. thermal effect

E. all above effects
353. A glass rod when rubbed with silk cloth is charged because__________?
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A. it gives away positive charge

B. its atoms are removed

C. it takes in proton

D. it gives away electrons
354. Helical coils can be used on___________________?
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A. high voltage side of high kVA rating transformers

B. high frequency transformers

C. high voltage side of small capacity transformers

D. low voltage side of high kVA transformers
355. When a voltage of one volt is applied, a circuit allows one micro ampere current to flow through it. The conductance of the circuit is___________?
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A. 1 milli-mho

B. none of the above

C. 1 n-mho

D. 106 mho

356. Helical coils can be used on___________?
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A. high voltage side of high kVA rating transformers

B. high voltage side of small capacity transformers

C. low voltage side of high kVA transformers

D. high frequency transformers

357. Power transformers are generally designed to have maximum efficiency around__________?
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A. half-load

B. near full-load

C. 10% overload

D. no-load

358. Which is the best conductor of electricity _______________?
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A. Copper

B. Iron

C. Silver

D. Carbon

359. Natural oil cooling is used for transformers up to a rating of____________?
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A. 1000 kVA

B. 3000 kVA

C. 250 kVA

D. 500 kVA

360. The path of the magnetic flux in transformer should have____________?
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A. high resistance

B. low reactance

C. low resistance

D. high reluctance

361. A 40 W bulb is connected in series with a room heater. If now 40 W bulb is replaced by 100 W bulb, the heater output will__________
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A. heater will burn out

B. increase

C. decrease

D. remain same

362. The resistance of a parallel circuit consisting of two branches is 12 ohms. If the resistance of one branch is 18 ohms, what is the resistance of the other ?
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A. 48 Q

B. 18 Q

C. 64 Q

D. 36 Q
363. In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are______________?
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A. none of the above

B. friction and windage losses

C. copper losses

D. hysteresis and eddy current losses
364. The substances which have a large number of free electrons and offer a low resistance are called____?
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A. insulators

B. conductors

C. semi-conductors

D. inductors

365. The four bulbs of 40 W each are connected in series swift a battery across them, which of the following statement is true_______________?
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A. The current through each bulb in same

B. The power dissipation in each bulb is not same

C. None of the above

D. The voltage across each bulb is not same

366. Which of the following can have negative temperature coefficient _____________?
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A. Liquid metals

B. Electrolytes

C. Metallic alloys

D. Compounds of silver

367. Negative voltage regulation is indicative that the load is___________?
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A. inductive only

B. capacitive only

C. none of the above

D. inductive or resistive

368. Which of the following does not change in an ordinary transformer ?
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A. Current

B. Frequency

C. Voltage

D. Any of the above

369. Ripple factor is the ratio of______________________?
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A. Rms value of the ac component of load voltage to the dc voltage

B. Peak value of the dc component of load voltage to the ac voltage

C. Average value of the ac component of load voltage to the peak value of voltage

D. Average value of the dc component of load voltage to the ac voltage

370. The path of a magnetic flux in a transformer should have______________?
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A. high reluctance

B. low reluctance

C. low resistance

D. high resistance

371. In a square wave operation of 3 phase CSIs, the power values are on for___________?
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A. 60 degree

B. 90 degree

C. 150 degree

D. 120 degree
372. In a transformer routine efficiency depends upon_____________?
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A. supply frequency

B. load current

C. power factor of load

D. both B. and (c)
373. The rating of a fuse wire is always expressed in________________?
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A. ampere-hours

B. kWh

C. amperes

D. ampere-volts

374. Which of the following property is not necessarily desirable in the material for transformer core ?
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A. Low hysteresis loss

B. High thermal conductivity

C. Mechanical strength

D. High permeability

375. The transfer function of PWM is generally developed in______________?
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A. Either A. or B.

B. Time domain

C. Frequency domain

D. None of these

376. The minimum charge on an ion is______________?
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A. equal to the atomic number of the atom

B. equal to the charge of the number of electrons in an atom (#) zero

C. equal to the charge of an electron
377. A closed switch has a resistance of_____________?
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A. about 500 ohms

B. infinity

C. zero

D. about 50 ohms

378. Three 60 W bulbs are in parallel across the 60 V power line. If one bulb burns open_________________?
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A. all three bulbs will light

B. rest of the two bulbs will not light

C. the other two bulbs will light

D. there will be heavy current in the main line

379. A nichrome wire used as a heater coil has the resistance of 2 2/m. For a heater of 1 kW at 200 V, the length of wire required will be_____________?
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A. 20 m

B. 40 m

C. 80 m

D. 60 m

380. In an electric kettle water boils in 10 m minutes. It is required to boil the boiler in 15 minutes, using same supply mains______________?
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A. length of heating element should be decreased

B. length of heating element should be increased

C. length of heating element has no effect on heating if water

D. none of the above

381. The maximum load that a power transformer can carry is limited by its________________?
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A. dielectric strength of oil

B. temperature rise

C. voltage ratio

D. copper loss

382. The hum in a transformer is mainly attributed to______________?
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A. magnetostriction

B. mechanical vibrations

C. oil in the transformer

D. load changes

383. The property of a conductor due to which it passes current is called___________?
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A. conductance

B. inductance

C. reluctance

D. resistance

384. An RC snubber network used in BJT__________?
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A. Improves the reverse bias safe operating area

B. All of these

C. Divert the collector current during turn off

D. Dissipates a fair amount of switching power

385. With rise in temperature the resistance of semi-conductors_________________?
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A. increases

B. first increases and then decreases

C. decreases

D. remains constant

386. Varistors are______________?
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A. resistors with zero temperature coefficient

B. insulators

C. non-linear resistors

D. carbon resistors

387. The ac voltage controller can be used for ___________?
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A. Lighting and heating control

B. Soft starting

C. On line transformer tap changing

D. All of these
388. Material used for construction of transformer core is usually___________________?
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A. silicon steel

B. wood

C. aluminium

D. copper

389. The number of electrons in the outer most orbit of carbon atom is___________?
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A. 7

B. 6

C. 4

D. 3

390. In an actual transformer the iron loss remains practically constant from no load to full load because:____________?
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A. permeability of transformer core remains constant

B. value of transformation ratio remains constant

C. secondary voltage remains constant

D. primary voltage remains constant

E. core flux remains practically constant
391. Bulbs in street lighting are all connected in_____________?
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A. series-parallel

B. end-to-end

C. parallel

D. series

392. A combination of synchronized leading edge and trailing edge modulation has also been used to control a____________?
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A. Boost single phase power factor converter

B. A buck dc dc converter to reduce ripple in the intermediate dc bus capacitor

C. Both A. and B.

D. None f these

393. Kingdom Protoctista includes_______________?
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A. Fungi

B. Prokaryotic organisms

C. Unicellular organisms

D. Eu-cariotiquic organisms

394. In a 3 phase VSI SPWM to use a single carrier signal and preserve the features of PWM technique, the normalized carrier frequency should be____________?
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A. Multiple of two

B. Odd multiple of three

C. Odd multiple of seven

D. Odd multiple of five

395. An ideal transformer will have maximum efficiency at a load such that?
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A. none of the above

B. copper loss iron loss

C. copper loss = iron loss
396. In variable frequency, PWM gain
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A. Phase lead helps to decrease the phase margin of the control loop

B. Phase lag helps to decrease the phase margin of the control loop

C. Phase lead helps to increase the phase margin of the control loop

D. Phase lag helps to increase the phase margin of the control loop

397. A 3 Q resistor having 2 A current will dissipate the power of_______________?
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A. 6 watts

B. 2 watts

C. 12 watts

D. 4 watts

398. Which of the following materials has a negative temperature co-efficient of resistance?
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A. Carbon

B. Aluminum

C. Brass

D. Copper

399. The degree of mechanical vibrations produced by the laminations of a transformer depends on____________?
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A. all of the above

B. tightness of clamping

C. size of laminations

D. gauge of laminations

400. In a lossless inverter, the average power absorbed in one period by the load must be__________?
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A. Equal to the average power supplied by the ac source

B. Greater than the average power supplied by the dc source

C. Lesser than the average power supplied by the dc source

D. Equal to the average power supplied by the dc source