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
4801. The ac output voltage waveform of VSI and AC output current waveform of CSI respectively is composed of___________?
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A. High dv / dt, high di / dt

B. High dv / dt, low di / dt

C. Low dv / dt, low di / dt

D. Low dv / dt, high di / dt

4802. For commutation in three phase PAC, normally balanced three phase voltages VR, VY and VB are connected to the three legs of the converter via______________?
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A. Three resistance

B. Three inductances

C. Three transistors

D. Three capacitances

4803. A single phase full bridge inverter can operated in load commutation mode in case load consist of______?
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A. RLC overdamped.

B. RL.

C. RLC underdamped.

D. RLC critically damped

4804. The transfer function of PWM is generally developed in______________?
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A. None of these

B. Frequency domain

C. Either A. or B.

D. Time domain

4805. 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. Average value of the ac component of load voltage to the peak value of voltage

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

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

4806. A thyristor can termed as__________?
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A. AC switch

B. DC switch

C. Both a and B

D. Square wave switch

4807. Double fourier series analysis of PWM is_____________?
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A. Two dimensional functions

B. Three dimensional functions

C. All of these

D. One dimensional functions

4808. The capacitance of reversed bised junction J2 in a thyristor is CJ2 = 20 pF and can be assumed to be independant of the off state voltage. The limiting value of the charging current to turn on the thyristor is 16 mA. What is the critical value of dv/dt?
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A. 600 V/s

B. 1000 V/s

C. 800 V/s

D. 1200 V/s

4809. Why resistor is used in Snubber circuit_________________ ?
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A. To minimize the discharging current

B. All of these

C. To minimize the loss

D. To minimize the charging current

4810. Practical way of obtaining static voltage equalization in series connected SCRs is by the use of____________?
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A. Resistors of the same value across each SCR

B. One resistor across the string

C. Resistors of different values across each SCR

D. One resistor in series with each SCR

4811. The maximum firing angle in the half wave controlled regulator is_____________?
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A. 190 degree

B. 210 degree

C. 180 degree

D. 200 degree

4812. Anode current in an SCR consists of____________?
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A. holes only

B. electrons only

C. either electron or holes

D. Both electron and holes

4813. In a 3 phase bridge rectifier the ripple frequency is _____________?
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A. Twice the input frequency

B. Three times the input frequency

C. Six times the input frequency

D. Equal to the input frequency

4814. Leakage current flows through the thyristor in_________?
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A. forward blocking mode

B. reverse blocking mode

C. both forward and reverse blocking mode

D. forward conduction mode

4815. By which one of the following we can measure the reliability of a string_____________?
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A. Derating factor

B. Reliability factor

C. Factor of safety

D. String efficient

4816. In single phase VSI, the harmonic which is not present is____________?
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A. 2nd

B. 5th

C. 3rd

D. 7th

4817. 60 thyrsistors are connected in series and parallel to form a 10 KV and 5.5 KA switch. Each thyristor is rated for 1.2 KV, 1 KA. The no. of parallel path are 6. The efficiency of the switch is______________________?
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A. 76.3 %

B. 83.30%

C. 91.60%

D. 90.90%

4818. Which of following is normally ON device?
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A. IGBT

B. BJT

C. TRIAC

D. SIT
4819. 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. Odd multiple of seven

B. Odd multiple of three

C. Multiple of two

D. Odd multiple of five

4820. SCRs are used in series to meet_______________?
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A. low voltage demand

B. high current demand

C. low current demand

D. high voltage demand
4821. Materials used in heat sink should have_____________?
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A. high melting point

B. large surface area

C. All of these

D. high thermal conductivity

4822. Between the incoming and outgoing devices in voltage commutation
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A. Large overlapping takes place

B. Small overlapping operation

C. No overlapping operation

D. None of these

4823. An ideal diode is___________?
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A. Unidirectional

B. Fixed voltage polarity

C. Only (a) and (c)

D. Bidirectional

4824. The output current in PWM DC DC converters is equal to___________?
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A. Product of an average inductor current and a function of duty ratio

B. None of these

C. Average value of the output inductor current

D. Either A. or B.
4825. During the commutation period in 3 phase converter, overlap time is____________?
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A. Dependent on the load current

B. Dependent on the voltage

C. Dependent on both the load current and load voltage behind the short circuit current

D. Independent on both the load current and load voltage

4826. Single phase VSI are mainly used in___________?
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A. Multilevel configuration

B. Ups

C. Power supplies

D. All of these
4827. AC power in a load can be controlled by using_____________?
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A. four SCRs in series

B. two SCRs in parallel opposition

C. three SCRs in series

D. two SCRs in series

4828. In radiative coupling, the emitter radiation field_____________?
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A. Decays as 1 / R, where R is the separation distance between the emitter and the receptor

B. Decays as R, where R is the separation distance between the emitter and the receptor

C. Decays as 1 / 2 R, where R is the separation distance between the emitter and the receptor

D. Decays as 2R, where R is the separation distance between the emitter and the receptor

4829. BCT is used for____________?
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A. Low power phase control

B. Low power current control

C. High power phase control

D. High power current control

4830. Double edge modulation eliminates certain harmonics when the reference is a__________?
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A. Sine wave

B. Square wave

C. Trapezoidal wave

D. Triangular wave

4831. Spread time is defined as the interval during which_____________?
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A. anode voltage drops from 10 % of its initial value to zero

B. anode current rises from 90 % to its final value

C. both (A) and (B)

D. anode current rises from 10 % to 90 % of its final value

4832. After proper turn on of thyristor____________?
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A. gate signal should present but can be removed

B. none of the above.

C. gate signal must be removed

D. gate signal is always present

4833. In a full wave rectifier, the rectification ratio is approximately equal to____________?
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A. 81%

B. 71%

C. 61%

D. 91%

4834. An SCR is made up of silicon because_____________?
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A. silicon has small leakage voltage than germanium

B. silicon has small leakage current than germanium

C. silicon has large leakage voltage than germanium

D. silicon has large leakage current than germanium

4835. IGBT stands for___________?
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A. Inductive gate bidirectional transistor

B. Insulated gate bipolar transistor

C. Inductive gate bipolar transistor

D. Insulated gate bidirectional transistor

4836. A Triac has three terminals viz ___________?
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A. Drain, source, gate

B. Two main terminal and a gate terminal

C. Cathode, anode, gate

D. None of the above

4837. Any electrical signal present in a circuit other than the desired signal is known as______________?
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A. All of these

B. Distortion

C. Noise

D. Interference

4838. In a silicon controlled rectifier, the load is connected___________?
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A. Across cathode

B. In series with anode

C. In series with cathode

D. Across anode

4839. MOSFET stands for______________?
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A. Metal oxide semiconductor field effect transistor

B. Molybdenum oxide semiconductor field effect transistor

C. Metal oxide semiconductor field effect transmitter

D. Metal oxide silicon field effect transistor

4840. A PNPN device having two gates is ___________?
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A. SUS

B. Diac

C. Triac

D. BCS
4841. Gate circuit or triggering circuit of a thyristor is
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A. high power circuit.

B. may be low power or high power circuit

C. lower power circuit.

D. magnetic circuit.

4842. SCR will be turned off when anode current is_______________?
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A. < latching current but greater than holding current and gate signal is 0.

B. less than holding current.

C. < latching current but greater than holding current and gate signal is present.

D. both (A) and (B).
4843. The ability of an electronic system to function properly in its intended electromagnetic environment and should not be a source of pollution to that electromagnetic environment is known as____________?
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A. Interference

B. Susceptibility

C. Emission

D. Electromagnetic compatibility
4844. In current commutated DC-DC choppers, the voltage spike appears across the load when_____________?
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A. Voltage across the commutating inductances collapses

B. The capacitance voltage adds to the supply voltage

C. Both A. and B.

D. None of these

4845. 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 dc source

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

C. Equal to the average power supplied by the ac source

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

4846. The latching current of GTO should be of order
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A. 100 mA

B. 500 mA

C. 1:00 AM

D. 2:00 AM

4847. Typical range of thyristor turn OFF time is______________?
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A. 3 10 s

B. 3 50 s

C. 3 500 s

D. 3 100 s
4848. With increase in firing angle,
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A. Both harmonic distortion and quality of input current increases

B. Harmonic distortion increases and quality of input current decreases

C. Harmonic distortion decreases and quality of input current increases

D. Both harmonic distortion and quality of input current decreases

4849. Which statement is true for latching current ___________?
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A. t is related to turn off process of the device.

B. It is related to conduction process of device.

C. It is related to turn on process of the device.

D. Both C and D.

4850. Number of PN junction in an SCR is____________?
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A. Three

B. Four

C. Two

D. Five