MCQOPTIONS
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MCQOPTIONS
This section includes 217 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.
| 101. |
As the breakdown voltage reached, the DIAC exhibits? |
| A. | Negative resistance characteristics |
| B. | Goes into avalanche condition |
| C. | Voltage drop snaps back |
| D. | All of these |
| Answer» E. | |
| 102. |
The effects of EMI can be reduced by____________? |
| A. | Suppressing emissions |
| B. | Reducing the efficiency of the coupling path |
| C. | Reducing the susceptibility of the receptor |
| D. | All of these |
| Answer» E. | |
| 103. |
Practical way of obtaining static voltage equalization in series connected SCRs is by the use of____________? |
| A. | One resistor across the string |
| B. | Resistors of the same value across each SCR |
| C. | Resistors of different values across each SCR |
| D. | One resistor in series with each SCR |
| Answer» C. Resistors of different values across each SCR | |
| 104. |
Advantages of HVDC transmission over AC system is / are____________? |
| A. | Reversal of power can be controlled by firing angle |
| B. | Very good dynamic behavior |
| C. | They can link two AC system operating unsynchronized |
| D. | All of these |
| Answer» E. | |
| 105. |
The conduction losses in IGBT is____________? |
| A. | More than that of MOSFET |
| B. | Lower than that of MOSFET |
| C. | Equal to that of MOSFET |
| D. | Equal to that of BJT |
| Answer» C. Equal to that of MOSFET | |
| 106. |
The average value of the output voltage in a step – down dc chopper is given by__________? |
| A. | V 0 = V s |
| B. | V 0 = D V s |
| C. | V 0 = V s / D |
| D. | V 0 = V s / ( 1 – D ) |
| Answer» C. V 0 = V s / D | |
| 107. |
In rectifiers, load current flow is_________? |
| A. | Unidirectional |
| B. | Bidirectional |
| C. | Either (a) or (b) |
| D. | Non directional |
| Answer» B. Bidirectional | |
| 108. |
In radiative coupling, the emitter radiation field_____________? |
| 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 |
| Answer» B. Decays as R, where R is the separation distance between the emitter and the receptor | |
| 109. |
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 | |
| 110. |
In BJT, the forward biased base emitter junction inject holes from base to emitter, the holes_______? |
| A. | Do not contribute to the collector current |
| B. | Result in net current flow component into the base |
| C. | Contribute to the collector current |
| D. | Only (a) and (b) |
| E. | Only (b) and (c) |
| Answer» E. Only (b) and (c) | |
| 111. |
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. | |
| 112. |
Number of PN junction in an SCR is____________? |
| A. | Two |
| B. | Three |
| C. | Four |
| D. | Five |
| Answer» C. Four | |
| 113. |
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. | |
| 114. |
In BJT, switching losses occurs___________? |
| A. | Only at turn – on |
| B. | Only at turn – off |
| C. | Both at turn on and off |
| D. | None of these |
| Answer» D. None of these | |
| 115. |
In a load commutated DC – DC chopper, the capacitor has a_____________? |
| A. | Symmetric triangular voltage across itself |
| B. | Symmetric rectangular voltage across itself |
| C. | Symmetric trapezoidal voltage across itself |
| D. | Symmetric sinusoidal voltage across itself |
| Answer» D. Symmetric sinusoidal voltage across itself | |
| 116. |
An SCR is made up of silicon because? |
| A. | silicon has large leakage current than germanium |
| B. | silicon has small leakage current than germanium |
| C. | silicon has small leakage voltage than germanium |
| D. | silicon has large leakage voltage than germanium |
| Answer» C. silicon has small leakage voltage than germanium | |
| 117. |
Anode of an operational SCR is _______________? |
| A. | Always positive w.r.t cathode |
| B. | Always negative w.r.t anode |
| C. | Always positive w.r.t anode |
| D. | Always negative w.r.t cathode |
| Answer» B. Always negative w.r.t anode | |
| 118. |
In a silicon controlled rectifier, the load is connected___________? |
| A. | Across anode |
| B. | In series with anode |
| C. | Across cathode |
| D. | In series with cathode |
| Answer» C. Across cathode | |
| 119. |
AC power in a load can be controlled by using____________? |
| A. | Two SCR’s in parallel opposition |
| B. | Two SCR’s in series |
| C. | Three SCR’s in series |
| D. | Four SCR’s in series |
| Answer» B. Two SCR’s in series | |
| 120. |
A rectifier with an external low pass filter is an example of______________? |
| A. | Indirect switch matrix circuits |
| B. | Direct switch matrix circuits |
| C. | Embedded converters |
| D. | All of these |
| Answer» C. Embedded converters | |
| 121. |
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 | |
| 122. |
If a shunt motor is started with its field winding open then? |
| A. | It will rotate at the same speed as that with its field winding closed |
| B. | It will rotate at less speed as that with its field winding closed |
| C. | It will rotate at dangerously high speed |
| D. | None of these |
| Answer» D. None of these | |
| 123. |
By which one of the following we can measure the reliability of a string_____________? |
| A. | String efficient |
| B. | Reliability factor |
| C. | Factor of safety |
| D. | Derating factor |
| Answer» E. | |
| 124. |
4 thyristors rated 200 V in series. The operating voltage of the string is 600 V. Derating factor of the string is_____________________? |
| A. | 0.75 |
| B. | 0.7 |
| C. | 0.2 |
| D. | 0.25 |
| Answer» E. | |
| 125. |
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 | |
| 126. |
In a full wave rectifier, the rectification ratio is approximately equal to____________? |
| A. | 61% |
| B. | 71% |
| C. | 81% |
| D. | 91% |
| Answer» D. 91% | |
| 127. |
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 | |
| 128. |
Spread time is defined as the interval during which_____________? |
| 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 |
| Answer» C. both (A) and (B) | |
| 129. |
Anode current in an SCR consists of____________? |
| A. | holes only |
| B. | electrons only |
| C. | either electron or holes |
| D. | Both electron and holes |
| Answer» B. electrons only | |
| 130. |
Power transistor are type of___________? |
| A. | B.JTs |
| B. | MOSFETs |
| C. | IGBTs |
| D. | All of above |
| Answer» E. | |
| 131. |
Maximum power loss occurs during_________________? |
| A. | delay time |
| B. | rise time |
| C. | spread time |
| D. | all |
| Answer» C. spread time | |
| 132. |
For series connected SCR’s dynamic equalising circuit consists of___________? |
| A. | R and C in series but with diode across C |
| B. | R and C in series but with diode across R |
| C. | Series R and diode with C across R |
| D. | Series R and diode with C across R |
| Answer» C. Series R and diode with C across R | |
| 133. |
Which statement is true ? |
| A. | Reverse recovery time ( trr ) > gate recovery time (tgr) |
| B. | Device turn OFF time ( tq ) > reverse recover time (trr) |
| C. | Circuit turn OFF time > device turn OFF time ( tq ) |
| D. | All of these |
| Answer» E. | |
| 134. |
Rise time is defined by the interval when____________? |
| A. | gate current rises from 90 % to 100 % of it final value |
| B. | anode voltage drops from 90 % to 10 % of its initial value |
| C. | anode current rises 10 % to 90 % of its final value |
| D. | both B and C |
| Answer» E. | |
| 135. |
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 | |
| 136. |
A power MOSFET has three terminals called___________? |
| A. | Collector, emitter and gate |
| B. | Drain, source and gate |
| C. | Drain, source and base |
| D. | Collector, emitter and base |
| Answer» C. Drain, source and base | |
| 137. |
Delay time is defined by the interval when_______________? |
| A. | gate current increases from 90 % to 100 % of its final value |
| B. | anode current reaches 10 % from forward leakage current |
| C. | anode voltage drops from 100 % to 90 % of its actual value |
| D. | all of these |
| Answer» E. | |
| 138. |
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 | |
| 139. |
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 | |
| 140. |
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 | |
| 141. |
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 | |
| 142. |
Compared to transistor, _________ have lower on state conduction losses and higher power handling capability? |
| A. | TRIACs |
| B. | Semi conductor diodes |
| C. | MOSFETs |
| D. | Thyristor |
| Answer» E. | |
| 143. |
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 | |
| 144. |
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 | |
| 145. |
COOLMOS device can be used in application up to power range of___________? |
| A. | 1 KVA |
| B. | 2 KVA |
| C. | 500 VA |
| D. | 100 KVA |
| Answer» C. 500 VA | |
| 146. |
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 | |
| 147. |
A modern power semiconductor device that combines the characteristic of BJT and MOSFET is_____________? |
| A. | IGBT |
| B. | FCT |
| C. | MCT |
| D. | GTO |
| Answer» B. FCT | |
| 148. |
IGBT combines the advantages of_____________? |
| A. | BJTs and SITs |
| B. | BJTs and MOSFETs |
| C. | SITs and MOSFETs |
| D. | None of these |
| Answer» C. SITs and MOSFETs | |
| 149. |
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 | |
| 150. |
Materials used in heat sink should have_____________? |
| A. | high thermal conductivity |
| B. | large surface area |
| C. | high melting point |
| D. | All of these |
| Answer» E. | |