electrical engineering MCQs – Page 240

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 Review each marked answer and report any item that may be outdated or unclear.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 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
4781. Thyristor can be protected from over voltages by using____________?
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A. fuse.

B. heat sink.

C. voltage clamping device.

D. snubber circuit.

4782. Form factor of a rectifier is the ratio of ______________?
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A. Peak value of current and voltage to its root mean square value

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

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

D. Root mean square value of voltage and current to its average value
4783. If holding current of a thyristor is 2 mA then latching current should be_____?
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A. 0.009 A.

B. 0.002 A.

C. 0.004 A.

D. 0.01 A.

4784. In reverse blocking mode of a thyristor______?
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A. junction J3 is in forward bias and J1, J2 in reverse bias.

B. junction J1, J3 is in reverse bias and J2 is in forward bias.

C. junction J1 and J2 is in forward bias and J3 is in reverse bias.

D. junction J2 is in reverse bias and J1, J3 is in forward bias.

4785. For bidirectional operation of converters____________?
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A. A series combination of controllable switch and a diode is used

B. A parallel combination of controllable switch and capacitor is used

C. A series combination of controllable switch and a capacitor is used

D. A parallel combination of controllable switch and a diode is used
4786. For power output higher than 15 kW, the suitable rectifier is________________?
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A. Poly phase

B. 3 phase

C. Single phase

D. Only (b) and (c)
4787. The IGBT resulted in higher switching speed and lower energy losses. It can be used for___________?
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A. Induction heating system

B. All of these

C. Constant voltage and frequency power supplies

D. Uninterruptible power supplies

4788. In bipolar modulation, the carrier is symmetric about zero with amplitude equal to Cm, the PWM output
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A. Switches between 1 and + 1

B. Switches between 1 / 2 and + 1 / 2

C. Switches between 0 and + 1

D. Zero

4789. The typical value of SCR for modern alternator is____________?
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A. 1.2.

B. 1.0.

C. 1.5.

D. 0.5.
4790. Bidirectional semiconductor device is___________?
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A. BJT

B. SCR

C. TRIAC

D. Diode

4791. The man made noise sources is / are_____________?
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A. Computers, digital electronics

B. All of these

C. Switches, radio interferences

D. Motors

4792. Due to non sinusoidal waveform of the input current, the power factor of the rectifier is____________?
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A. Negatively affected by firing angle

B. Negatively affected by distortion of the input current

C. Positively affected by both firing angle and distortion of the input current

D. Both (a) and (b)
4793. Voltage commutation circuit can be converted into a current commutation by interchanging the positions of____________?
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A. Capacitor and SCR

B. Diode and capacitor

C. Capacitor and load

D. Inductor and capacitor

4794. To meet high current demand we use SCRs in______________?
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A. series connection.

B. parallel connection.

C. anti parallel connection.

D. both B and C.

4795. Switching frequency of SITH is____________?
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A. 5 KHz

B. 60 KHz

C. 100 KHz

D. 10 KHz

4796. The switching function of semiconductor devices can be characterized with____________?
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A. Duty ratio, frequency and time delay

B. Duty ratio only

C. Duty ratio and frequency

D. Frequency only

4797. The power demand can be estimated approximately by___________?
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A. Statistical method

B. Mathematical method

C. Load survey method

D. Economic parameters

4798. A modern power semiconductor device that combines the characteristic of BJT and MOSFET is_____________?
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A. GTO

B. IGBT

C. MCT

D. FCT

4799. In the SPWM, the modulating signal is___________?
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A. Saw tooth

B. Sinusoidal

C. Square

D. Triangular

4800. The effects of EMI can be reduced by_____________?
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A. Reducing the efficiency of the coupling path

B. Suppressing emissions

C. Reducing the susceptibility of the receptor

D. All of these