MCQOPTIONS
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MCQOPTIONS
This section includes 204 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Which one is most suitable power device for high frequency (>100 KHz) switching application? |
| A. | BJT |
| B. | Power MOSFET |
| C. | Schottky diode |
| D. | Microwave transistor |
| Answer» C. Schottky diode | |
| 2. |
Which semiconductor device acts like a diode and two transistor? |
| A. | UJT |
| B. | Diac |
| C. | Triac |
| D. | SCR |
| Answer» D. SCR | |
| 3. |
Which statement is true for latching current ___________? |
| A. | It 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. |
| Answer» D. Both C and D. | |
| 4. |
Which triggering is the most reliable____________? |
| A. | Forward voltage triggering |
| B. | Gate triggering |
| C. | dV / dt triggering |
| D. | Thermal triggering |
| Answer» C. dV / dt triggering | |
| 5. |
Why resistor is used in Snubber circuit_________________ ? |
| A. | To minimize the loss |
| B. | To minimize the charging current |
| C. | To minimize the discharging current |
| D. | All of these |
| Answer» D. All of these | |
| 6. |
With gate open, the maximum anode current at which SCR is turned off from ON condition is called____________? |
| A. | breakdown voltage |
| B. | peak reverse voltage |
| C. | holding current |
| D. | latching current |
| Answer» D. latching current | |
| 7. |
Which of the following is used in SCR to protect from high dV / dt__________________? |
| A. | Snubber circuit |
| B. | Fuse |
| C. | Equalizing circuit |
| D. | Circuit breaker |
| Answer» B. Fuse | |
| 8. |
Which of the following is used in heat sink_____________? |
| A. | Iron |
| B. | Aluminium |
| C. | Carbon |
| D. | Silver |
| Answer» C. Carbon | |
| 9. |
Which of the following is true about SIT? |
| A. | SIT is a high power, high frequency device |
| B. | SIT is a high power, low frequency device |
| C. | SIT is a high power, high voltage device |
| D. | SIT is a low power, high frequency device |
| Answer» B. SIT is a high power, low frequency device | |
| 10. |
Which of the following is disadvantage of fast recovery diodes? |
| A. | Recovery is only 5 µs |
| B. | Recovery is only 50 µs |
| C. | Doping is carried out |
| D. | None of these |
| Answer» D. None of these | |
| 11. |
Which of following is not a power transistor? |
| A. | IGBTs |
| B. | COOLMOS |
| C. | TRIAC |
| D. | SITS |
| Answer» D. SITS | |
| 12. |
Which of following is normally ON device? |
| A. | SIT |
| B. | BJT |
| C. | TRIAC |
| D. | IGBT |
| Answer» B. BJT | |
| 13. |
Which of following devices has highest di/dt and dv/dt capability? |
| A. | SIT |
| B. | SITH |
| C. | GTO |
| D. | SCR |
| Answer» D. SCR | |
| 14. |
Which following is a two terminal three layer device? |
| A. | BJT |
| B. | Power dioed |
| C. | MOSFET |
| D. | None of above |
| Answer» E. | |
| 15. |
When a large surge current of very short duration flows through a thyristor then which one of the following device will operate to protect the thyristor ___________? |
| A. | CB |
| B. | Snubber circuit |
| C. | Voltage clamping device |
| D. | Fast acting current limiting device (FACL fuse) |
| Answer» E. | |
| 16. |
What may happen high dV / dt____________? |
| A. | Unwanted turn ON |
| B. | Breakdown of J2 junction |
| C. | Both A and B |
| D. | Anyone of these |
| Answer» D. Anyone of these | |
| 17. |
What is used to protect the SCR from over current ________________? |
| A. | CB and fuse |
| B. | Heat sink |
| C. | Snubber circuit |
| D. | Voltage clamping device |
| Answer» B. Heat sink | |
| 18. |
What is used to protect a thyristor from high di / dt conditions__________? |
| A. | Fuse |
| B. | Snubber circuit |
| C. | Inductor |
| D. | Voltage clamping device |
| Answer» D. Voltage clamping device | |
| 19. |
What happen due to high di / dt____________? |
| A. | Breakdown of junction |
| B. | Local hot spot |
| C. | Insulation failure |
| D. | None of these |
| Answer» C. Insulation failure | |
| 20. |
Voltage commutation circuit can be converted into a current commutation by interchanging the positions of____________? |
| A. | Diode and capacitor |
| B. | Capacitor and SCR |
| C. | Inductor and capacitor |
| D. | Capacitor and load |
| Answer» B. Capacitor and SCR | |
| 21. |
Very large values of modulation index (greater than 3.24) lead to___________? |
| A. | Square AC output voltage |
| B. | Sine AC output voltage |
| C. | Triangular AC output voltage |
| D. | Trapezoidal AC output voltage |
| Answer» B. Sine AC output voltage | |
| 22. |
Unipolar modulation is generally used in____________? |
| A. | AC – AC converters |
| B. | AC – DC converters |
| C. | DC – AC converters |
| D. | DC – DC converters |
| Answer» E. | |
| 23. |
Under over voltage condition impedance offered by the voltage clamping device is__________? |
| A. | low |
| B. | High |
| C. | moderate |
| D. | infinity |
| Answer» B. High | |
| 24. |
Under normal operating condition voltage clamping device offers impedance of_________? |
| A. | high value |
| B. | low value |
| C. | zero value |
| D. | moderate value |
| Answer» B. low value | |
| 25. |
Under harmonic free load voltages, the 3 phase VSI_____________? |
| A. | Does not contains second harmonic |
| B. | Does not contains third harmonic |
| C. | Does not contains fifth harmonic |
| D. | Does not contains seventh harmonic |
| Answer» B. Does not contains third harmonic | |
| 26. |
Typical range of thyristor turn OFF time is______________? |
| A. | 3 – 10 µs |
| B. | 3 – 50 µs |
| C. | 3 – 100 µs |
| D. | 3 – 500 µs |
| Answer» D. 3 – 500 µs | |
| 27. |
TRIAC is a semiconductor power electronic device which contains____________? |
| A. | Two SCR’s connected in reverse parallel |
| B. | Two SCR’s connected in parallel |
| C. | Two SCR’s connected in series |
| D. | Two BJT’s connected in series |
| Answer» B. Two SCR’s connected in parallel | |
| 28. |
Transformer utilization factor is a measure of the merit of a rectifier circuit. It is the ratio of_______________? |
| A. | AC input power to the transformer volt – amp rating required by secondary |
| B. | AC input power to the transformer volt – amp rating required by primary |
| C. | DC output power to the transformer volt – amp rating required by secondary |
| D. | DC output power to the transformer volt – amp rating required by primary |
| Answer» D. DC output power to the transformer volt – amp rating required by primary | |
| 29. |
To meet high current demand we use SCRs in______________? |
| A. | series connection |
| B. | parallel connection |
| C. | anti parallel connection |
| D. | both B and C. |
| Answer» C. anti parallel connection | |
| 30. |
To detect an over – current fault condition, the most reliable method is to connect a_____________? |
| A. | Current sensor across IGBT |
| B. | Voltage sensor across IGBT |
| C. | Current sensor in series with IGBT |
| D. | Voltage sensor in series with IGBT |
| Answer» D. Voltage sensor in series with IGBT | |
| 31. |
Thyristor is nothing but a____________? |
| A. | Controlled transistor |
| B. | Controlled switch |
| C. | Amplifier with higher gain |
| D. | Amplifier with large current gain |
| Answer» C. Amplifier with higher gain | |
| 32. |
Thyristor can be protected from over voltages by using |
| A. | 23 mA |
| B. | 40 mA |
| C. | 10 mA |
| D. | 60 mA |
| Answer» D. 60 mA | |
| 33. |
Thyristor can be protected from over voltages by using____________? |
| A. | voltage clamping device |
| B. | fuse |
| C. | heat sink |
| D. | snubber circuit |
| Answer» B. fuse | |
| 34. |
Thermal voltage VT can be given by____________? |
| A. | Kq/T |
| B. | KT/q |
| C. | qT/K |
| D. | (K2/q)(T + 1/T – 1) |
| Answer» C. qT/K | |
| 35. |
The typical value of SCR for modern alternator is____________? |
| A. | 1.5 |
| B. | 0.5 |
| C. | 1.0 |
| D. | 1.2 |
| Answer» C. 1.0 | |
| 36. |
The typical time of rising time lies between______________? |
| A. | 10 – 20 µs |
| B. | 40 – 60 µs |
| C. | 1 – 4 µs |
| D. | 90 – 100 µs |
| Answer» D. 90 – 100 µs | |
| 37. |
The turn-on time of an SCR with inductive load is 20 µs. The puls train frequency is 2.5 KHz with a mark/space ratio of 1/10, then SCR will___________? |
| A. | Turn on |
| B. | Not turn on |
| C. | Turn on if inductance is removed |
| D. | Turn on if pulse frequency us increased to two times |
| Answer» B. Not turn on | |
| 38. |
The transfer function of PWM is generally developed in______________? |
| A. | Time domain |
| B. | Frequency domain |
| C. | Either A. or B. |
| D. | None of these |
| Answer» D. None of these | |
| 39. |
The switching function of semiconductor devices can be characterized with___________? |
| A. | Duty ratio only |
| B. | Frequency only |
| C. | Duty ratio and frequency |
| D. | Duty ratio, frequency and time delay |
| Answer» E. | |
| 40. |
The switching function of semiconductor devices can be characterized with____________? |
| A. | Duty ratio only |
| B. | Frequency only |
| C. | Duty ratio and frequency |
| D. | Duty ratio, frequency and time delay |
| Answer» E. | |
| 41. |
The sum of all phase current in a star connected primary winding with no neutral connection is equal to___________? |
| A. | Phase current |
| B. | Three times the phase current |
| C. | Three times the line current |
| D. | Zero at all times |
| Answer» E. | |
| 42. |
The square wave operation of 3 phase VSI lines contains the harmonics. The amplitudes are____________? |
| A. | Directly proportional to their harmonic order |
| B. | Inversely proportional to their harmonic order |
| C. | Not related to their harmonic order |
| D. | None of these |
| Answer» C. Not related to their harmonic order | |
| 43. |
The reverse recovery time of diode is trr = 3 μs and the rate off all of the diode current is di/dt = 30 A/μs. The storage charge current QRR is___________? |
| A. | 130 μs |
| B. | 135 μs |
| C. | 140 μs |
| D. | 145 μs |
| Answer» C. 140 μs | |
| 44. |
The power MOSFET device is a___________? |
| A. | Current controlled unipolar device |
| B. | Voltage controlled unipolar device |
| C. | Current controlled bipolar device |
| D. | Voltage controlled bipolar device |
| Answer» C. Current controlled bipolar device | |
| 45. |
The power demand can be estimated approximately by____________? |
| A. | Load survey method |
| B. | Mathematical method |
| C. | Statistical method |
| D. | Economic parameters |
| Answer» D. Economic parameters | |
| 46. |
The power demand can be estimated approximately by___________? |
| A. | Load survey method |
| B. | Mathematical method |
| C. | Statistical method |
| D. | Economic parameters |
| Answer» D. Economic parameters | |
| 47. |
The phase angle of gate signal in TRIAC can be shifted by using_____________? |
| A. | A capacitor |
| B. | A variable resistor |
| C. | An inductor |
| D. | Only (a) and (b) |
| Answer» E. | |
| 48. |
The output power of the cascaded amplifier / attenuator system can be determined using___________? |
| A. | Actual gain of amplifier |
| B. | Actual gain of amplifier and attenuator |
| C. | Gain in dB of amplifier and attenuator |
| D. | Actual gain of attenuator |
| Answer» C. Gain in dB of amplifier and attenuator | |
| 49. |
The output current in PWM DC – DC converters is equal to___________? |
| A. | Average value of the output inductor current |
| B. | Product of an average inductor current and a function of duty ratio |
| C. | Either A. or B. |
| D. | None of these |
| Answer» D. None of these | |
| 50. |
The opposite of susceptibility is___________? |
| A. | Immunity |
| B. | Emission |
| C. | Interference |
| D. | Electromagnetic compatibility |
| Answer» B. Emission | |