electrical engineering MCQs – Page 61

Practise multiple-choice questions from electrical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

electrical engineering Mcqs

1. economics of power generation 2. analog electronics 3. solid state switching circuits 4. parallel circuits 5. switchgear and protection 6. op amp circuits 7. transistor audio power amplifiers 8. electrostatics 9. heating and welding 10. multi stage transistor amplifiers 11. passive filters 12. network theorems 13. regulated d c power supply 14. a c fundamentals circuits and circuit theory 15. electromagnetic induction 16. power electronics 17. magnetism and electromagnetism 18. transformers 19. modulation and demodulation 20. d c generators 21. semiconductor theory 22. single phase induction motors 23. semiconductor diode 24. hybrid parameters 25. digital electronics 26. oscillators 27. earthing or grounding 28. single stage transistor amplifiers 29. d c motors 30. transistor biasing 31. amplifiers with negative feedback 32. basic electrical 33. electronic instruments 34. synchronous motors 35. field effect transistors fet 36. magnetic circuit 37. control systems 38. industrial drives 39. power generation 40. series parallel circuits 41. transistor tuned amplifiers 42. electrical engineering materials 43. rectifiers and converters 44. integrated circuits 45. scr silicon controlled rectifiers 46. cables 47. polyphase induction motors 48. measurement and instrumentation 49. transistors 50. electrical machine design 51. electrolysis and storage of batteries 52. electric traction 53. transmission and distribution

1201. For power factor correction, synchronous motors operate at____________?
0

A. normal load with minimum excitation

B. no-load and under-excited fields

C. normal load with zero excitation

D. no-load and greatly over-excited fields

1202. A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because?
0

A. synchronous motor has large airgap

B. synchronous motor has no slip

C. mechanical load on the rotor remains constant

D. stator supply is not required to produce magnetic field

1203. The back e.m.f. of a synchronous motor depends on______________?
0

A. speed

B. load angle

C. all of the above

D. load

1204. Annual depreciation of the plant it proportional to the earning capacity of the plant vide
0

A. reducing balances depreciation

B. none of the above

C. sinking fund depreciation

D. straight line depreciation

1205. The power demand can be estimated approximately by____________?
0

A. Statistical method

B. Load survey method

C. Economic parameters

D. Mathematical method

1206. In a synchronous motor, the breakdown torque is__________?
0

A. directly proportional to applied voltage

B. none of the above

C. directly proportional to the square of the applied voltage

D. inversely proportional to applied voltage

1207. The effect of electric shock on human body depends on which of the following?
0

A. current

B. voltage

C. all of the above

D. duration of contact

1208. A synchronous machine with large air gap has______________?
0

A. a small value of inherent regulation

B. a higher value of stability limit

C. all of the above

D. a higher synchronizing power which makes the machine less sensitive to load variations

1209. In a 3-phase, 4-pole, 50 Hz synchronous motor, the frequency, pole number and load torque all are halved. The motor speed will be____________?
0

A. none of the above

B. 3000 r.p.m.

C. 750 r.p.m.

D. 1500 r.p.m.

1210. The form factor is the ratio of_______?
0

A. peak value to r.m.s. value

B. r.m.s. value to average value

C. none of the above

D. average value to r.m.s. value

1211. The operating speed of a synchronous motor can be changed to new fixed value by___________?
0

A. changing the supply voltage

B. changing frequency

C. using brakes

D. changing the load

1212. A low utilization factor for a plant indicates that
0

A. plant is used for stand by purpose only

B. plant is used for peak load as well as base load

C. plant is under maintenance

D. plant is used for base load only

1213. ____________is the reserved generating capacity available for service under emergency conditions which is not kept in operation but in working order.
0

A. Firm power

B. Cold reserve

C. Hot reserve

D. Spinning reserve

1214. A star circuit has element of resistance R/2. The equivalent delta elements will be_____________?
0

A. 4R

B. 2R

C. fi?

D. R/6

1215. In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage, then
0

A. the motor is said to be fully loaded

B. the torque generated is maximum

C. the excitation is said to be hundred per cent

D. the excitation is said to be zero per cent

1216. When the stator windings are connected in such a fashion that the number of poles are made half, the speed of the rotor of a synchronous motor___________?
0

A. decreases to half the original value

B. remains same as the original value

C. tends to becomes zero

D. increases to two times the original value

1217. Load shedding is possible through which of the following?
0

A. Any of the above

B. Voltage reduction

C. Frequency reduction

D. Switching of the loads

1218. The reactance offered by a capacitor to alternating current of frequency 50 Hz is 20 Q. If frequency is increased to 100 Hz, reactance becomes_______ohms?
0

A. 10

B. 15

C. 5

D. 2.5

1219. Stability of a synchronous machine:
0

A. increases with increase in its excitation

B. decreases with increase in its excitation

C. remains unaffected with increase in excitation

D. any of the above

1220. Which of the following is the disadvantage of static capacitor for power factor improvement?
0

A. All of the above

B. Easily damaged by high voltage

C. Cannot be repaired

D. Short service life

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