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
4751. The power demand can be estimated approximately by____________?
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A. Mathematical method

B. Load survey method

C. Statistical method

D. Economic parameters

4752. In a load commutated DC DC chopper, the capacitor has a_____________?
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A. Symmetric trapezoidal voltage across itself

B. Symmetric rectangular voltage across itself

C. Symmetric triangular voltage across itself

D. Symmetric sinusoidal voltage across itself

4753. AC power in a load can be controlled by using____________?
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A. Three SCRs in series

B. Two SCRs in parallel opposition

C. Four SCRs in series

D. Two SCRs in series

4754. If all the SCRs of 3 phase PAC is replaced by diodes, they would be triggered_____________?
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A. 120 degree after the zero crossing of the corresponding line voltages

B. 60 degree after the zero crossing of the corresponding line voltages

C. 60 degree before the zero crossing of the corresponding line voltages

D. 120 degree before the zero crossing of the corresponding line voltages

4755. As the breakdown voltage reached, the DIAC exhibits?
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A. All of these

B. Goes into avalanche condition

C. Voltage drop snaps back

D. Negative resistance characteristics

4756. The square wave operation of 3 phase VSI lines contains the harmonics. The amplitudes are____________?
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A. None of these

B. Directly proportional to their harmonic order

C. Inversely proportional to their harmonic order

D. Not related to their harmonic order

4757. In a square wave operation of 3 phase CSIs, the power values are on for___________?
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A. 90 degree

B. 150 degree

C. 120 degree

D. 60 degree

4758. In a push pull converter, the filter capacitor can be obtained as____________?
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A. Cmin= ( 1 2 D ) V / 32 ( Vr L f2 )

B. Cmin= ( 1 2 D ) V / 42 ( Vr L f2 )

C. Cmin = V / ( Vr L f2 )

D. Cmin= ( 1 D ) V / ( Vr L f2 )

4759. DIAC and TRIAC both are semiconductors devices and conduct in____________________?
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A. DIAC conducts in forward direction and TRIAC conducts in reverse direction

B. Both conducts in forward direction

C. Both conducts in reverse direction

D. Both conducts in either direction
4760. Very large values of modulation index (greater than 3.24) lead to___________?
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A. Sine AC output voltage

B. Square AC output voltage

C. Trapezoidal AC output voltage

D. Triangular AC output voltage

4761. ON state voltage drop across SCR lie between the range_____________?
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A. 1 1.5 V.

B. 0.5 1 V.

C. 1.5 2 V.

D. 0 0.5 V.

4762. In a 3 phase half wave rectifier, when firing angle is less than 90 degree, then the average dc output voltage becomes__________________?
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A. Zero

B. Negative

C. Positive

D. None of these

4763. Snubber circuit is used with SCR_________________?
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A. either series or parallel

B. in series

C. in parallel

D. anti parallel

4764. For swept frequency measurements, the input impedance of the mismatched transmission line would vary with frequency as the electrical length of the transmission line would
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A. Increase with frequency

B. Decrease with frequency

C. Either A. or B.

D. Remains same with change in frequency

4765. In BJT, switching losses occurs___________?
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A. Only at turn on

B. Only at turn off

C. Both at turn on and off

D. None of these

4766. Silicon controlled rectifier can be turned on____________?
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A. By applying a gate pulse and turned off only when current becomes zero

B. By making current non zero and turned off by making current zero

C. And turned off by applying gate pulse

D. By applying a gate pulse and turned off by removing the gate pulse

4767. If a shunt motor is started with its field winding open then___________?
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A. None of these

B. It will rotate at dangerously high speed

C. It will rotate at less speed as that with its field winding closed

D. It will rotate at the same speed as that with its field winding closed

4768. Advantages of HVDC transmission over AC system is / are____________?
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A. Reversal of power can be controlled by firing angle

B. They can link two AC system operating unsynchronized

C. All of these

D. Very good dynamic behavior

4769. Thyristor can be protected from over voltages by using
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A. 23 mA.

B. 60 mA.

C. 40 mA.

D. 10 mA.
4770. Let of a thyristor Vc1, Vc2, Vc3 are forward break over voltage for gate current Ig1, Ig2, Ig3 respectively. Then________________?
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A. Vc1 > Vc2 > Vc3 when Ig1 < Ig2 < Ig3.

B. Vc1 = Vc2 = Vc3 any value of Ig.

C. Vc1 > Vc2 > Vc3 when Ig1 > Ig2 > Ig3.

D. Vc1 > Vc2 > Vc3 when Ig1 aYEN Ig2 &Atil

4771. Compared to transistor, _________ have lower on state conduction losses and higher power handling capability?
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A. MOSFETs

B. Thyristor

C. Semi conductor diodes

D. TRIACs

4772. The power MOSFET device is a___________?
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A. Current controlled bipolar device

B. Voltage controlled unipolar device

C. Voltage controlled bipolar device

D. Current controlled unipolar device

4773. Choppers is a_______________?
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A. DC AC converters

B. DC DC converters

C. AC DC converters

D. AC AC converters

4774. During which time maximum conduction spreading take place in the thyristor during turn ON?
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A. Rise time

B. Delay time

C. Spread time

D. Same for every case

4775. An SCR can be used___________?
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A. All of these

B. as static conductor

C. for speed control of dc shunt motor

D. for power control

4776. The switching function of semiconductor devices can be characterized with___________?
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A. Duty ratio only

B. Duty ratio and frequency

C. Frequency only

D. Duty ratio, frequency and time delay
4777. A power MOSFET has three terminals called___________?
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A. Collector, emitter and gate

B. Drain, source and base

C. Drain, source and gate

D. Collector, emitter and base

4778. The opposite of susceptibility is___________?
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A. Interference

B. Electromagnetic compatibility

C. Emission

D. Immunity
4779. A capacitive load in voltage source inverters generates ________________?
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A. Small current spikes and can be increased by using an inductive filter

B. Small current spikes and can be reduced by using an inductive filter

C. Large current spikes and can be increased by using an inductive filter

D. Large current spikes and can be reduced by using an inductive filter
4780. The ac voltage controller can be used for ___________?
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A. On line transformer tap changing

B. Lighting and heating control

C. All of these

D. Soft starting

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