MCQOPTIONS
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MCQOPTIONS
This section includes 257 Mcqs, each offering curated multiple-choice questions to sharpen your Power Electronics knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
In given fig., V |
| A. | 100 V, 100 V, 100 V |
| B. | 100 V, 0, 200 V |
| C. | 100 V, 0, 200 V |
| D. | 100 V, 0, 100 V |
| Answer» D. 100 V, 0, 100 V | |
| 52. |
The speed and torque of induction motors can be varied by which of the following means: |
| A. | 1 only |
| B. | 2 only |
| C. | 1 and 2 only |
| D. | 1, 2 and 3 |
| Answer» E. | |
| 53. |
In given fig. capacitor C is initially charged with voltage V |
| A. | <table><tr><td rowspan="2">0,</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>V<sub>0</sub> </center></td></tr><tr><td style="text-align: center;">R</td></tr></table> |
| B. | <table><tr><td rowspan="2"> V<sub>0</sub>,</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>V<sub>0</sub> </center></td></tr><tr><td style="text-align: center;">R</td></tr></table> |
| C. | <table><tr><td rowspan="2"> V<sub>0</sub>, </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>V<sub>0</sub></center></td></tr><tr><td style="text-align: center;">R</td></tr></table> |
| D. | |
| E. | <table><tr><td rowspan="2">V<sub>0</sub>,</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>V<sub>0</sub></center></td></tr><tr><td style="text-align: center;">R</td></tr></table> |
| Answer» C. <table><tr><td rowspan="2"> V<sub>0</sub>, </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>V<sub>0</sub></center></td></tr><tr><td style="text-align: center;">R</td></tr></table> | |
| 54. |
Consider the following statements: The overlap angle of a phase controlled converter would increase on increasing the |
| A. | 1, 2, 3 |
| B. | 2, 3, 4 |
| C. | 1, 2, 4 |
| D. | 1, 3, 4 |
| Answer» D. 1, 3, 4 | |
| 55. |
In order to obtain static voltage equalization in series connected SCRs, connections are made of |
| A. | One resistor across the string |
| B. | Resistors of different values across each SCR |
| C. | Resistors of the same value across each SCR |
| D. | One resistor in series with the string |
| Answer» D. One resistor in series with the string | |
| 56. |
Static induction thyristors have: |
| A. | High dv/dt and low di/dt |
| B. | Low dv/dt and high di/dt |
| C. | Low dv/dt and low di/dt |
| D. | High dv/dt and high di/dt |
| Answer» E. | |
| 57. |
In given fig., zero centre and ideal PMMC voltmeters M |
| A. | 10 V, 10 V |
| B. | 0, 10 V |
| C. | 10 V, 7 07 V |
| D. | 10V, 7 07 V |
| Answer» B. 0, 10 V | |
| 58. |
A SCHOTTKY diode is a: |
| A. | Majority carrier device |
| B. | Minority carrier device |
| C. | Fast recovery diode |
| D. | Both a majority and a minority carrier diode |
| Answer» B. Minority carrier device | |
| 59. |
For a sinusoidal input voltage |
| A. | m + n |
| B. | m n |
| C. | mn |
| D. | n/(m + n) |
| Answer» E. | |
| 60. |
In given fig. capacitor C is charged to V0 = 50 V with upper plate positive. Switch S is closed at t = 0. Current through the circuit at t = 0 and final voltage across are respectively |
| A. | 15 A, 200V |
| B. | 20 A, 200V |
| C. | 25 A, 250V |
| D. | 15 A, 150V |
| Answer» B. 20 A, 200V | |
| 61. |
MOS controlled thyristors have: |
| A. | 1, 2, 3 |
| B. | 3, 4, 5 |
| C. | 2, 3, 4 |
| D. | 1, 3, 5 |
| Answer» B. 3, 4, 5 | |
| 62. |
In a non-volatile memory device: |
| A. | Data contained in them is lost when the power turned off |
| B. | Data contained in them is not lost when the power turned off |
| C. | Data contained in them is permanent and not rewritable |
| D. | None of these |
| Answer» C. Data contained in them is permanent and not rewritable | |
| 63. |
A semi conductor memory which allows the eraser of the information stared in it so that new information can be stared in it referred as: |
| A. | RAM |
| B. | ROM |
| C. | EPROM |
| D. | EEPROM |
| Answer» D. EEPROM | |
| 64. |
Following is not application of computers: |
| A. | RAM |
| B. | CAD |
| C. | CAM |
| D. | CAI/CAF |
| Answer» B. CAD | |
| 65. |
A storage device where the access time is effectively independent of the location of data is called as: |
| A. | Direct access |
| B. | Primary storage |
| C. | Secondary storage |
| D. | None of these |
| Answer» B. Primary storage | |
| 66. |
Buffer is device/storage area where: |
| A. | Data is permanently stored |
| B. | Data is temporarily stored |
| C. | Data error occurs |
| D. | None of these |
| Answer» C. Data error occurs | |
| 67. |
The efficiency of a chopper can be expected in the range: |
| A. | 50 to 55 per cent |
| B. | 65 to 72 per cent |
| C. | 82 to 87 per cent |
| D. | 92 to 99 per cent |
| Answer» E. | |
| 68. |
A 1 full bridge diode rectifier delivers a load current of 10 A, which is ripple free. Average and rms values of diode currents are respectively |
| A. | 10 A, 7 07 A |
| B. | 5A, 10 A |
| C. | 5A, 7 07 A |
| D. | 7 07 A, 5A |
| Answer» D. 7 07 A, 5A | |
| 69. |
Compact disk is: |
| A. | Secondary storage |
| B. | Stores serial and sequential files |
| C. | Carrier |
| D. | All of these |
| Answer» E. | |
| 70. |
Cassette tape is: |
| A. | Primary storage |
| B. | Secondary storage |
| C. | Volatile storage |
| D. | None of these |
| Answer» C. Volatile storage | |
| 71. |
Which of the following thyristors are Gate turned OFF device? |
| A. | 1 only |
| B. | 2 only |
| C. | 1 and 2 only |
| D. | 1, 2 and 3 only |
| Answer» E. | |
| 72. |
An ideal rectifier should have transformer utilisation factor (TUF) of 1. If the actual TUF is 3 5, It shows that |
| A. | Diode is under loaded |
| B. | The transformer must be 3 5 times large |
| C. | The transformer should be only 1/3 5 times the ideal size |
| D. | The ripple factor is low |
| Answer» C. The transformer should be only 1/3 5 times the ideal size | |
| 73. |
Which of the following is preferred for VHF/UHF applications? |
| A. | BJT |
| B. | MOSFET |
| C. | SIT |
| D. | IGBT |
| Answer» D. IGBT | |
| 74. |
When transistors are used in series or parallel a snubber circuit is used to |
| A. | Control the current |
| B. | Control the voltage |
| C. | Limit di/dt |
| D. | All of these |
| Answer» D. All of these | |
| 75. |
In a convertional reverse blocking thyristor |
| A. | External layers are lightly doped and internal layers are heavily doped |
| B. | External layers are heavily doped and internal layers are lightly doped |
| C. | The P-layers are heavily doped and the n-layers are lightly doped |
| D. | The P-layers are lightly doped and the n-layers are heavely doped |
| Answer» E. | |
| 76. |
In a 3-phase rectifier circuit, thyristor number 1, 2 and 3 are connected respectively to R, Y, and B phases of the star connected transformer secondary. When the current is being commutated from thyristor No. 1 to No. 2 the effect of the transformer leakage and the a.c. system inductance will be such that it will |
| A. | Prolong the conduction in No. 1 at the scheduled time but delay the turn ON of No. 2 correspondingly |
| B. | Stop the conduction in No. 1 at the scheduled time but delay the turn-ON of No. 2 |
| C. | Produce conduction in both No. 1 and No. 2 in parallel for an overlapping period through a transient |
| D. | Double the voltage o/p through a commutation transient |
| Answer» D. Double the voltage o/p through a commutation transient | |
| 77. |
A-3 phase converter feeds a pure resistive load at a firing angle of = 60 . The average value of current flowing in the load is 10 A. If a very large inductance is connected in the load circuit, then the |
| A. | Average value of current will remain as 10 A |
| B. | Average value of current will become greater than 10A |
| C. | Average value of current will become less than 10A. |
| D. | Trend of variation of current cannot be predicted unless the exact value of the inductance connected is known |
| Answer» B. Average value of current will become greater than 10A | |
| 78. |
Match the devices on the left hand side with the circuit symbols on right hand side |
| A. | BJT |
| B. | MOSFET |
| C. | IGBT |
| D. | MCT |
| E. | None of these |
| Answer» F. | |
| 79. |
A local storage area in which the result of the arithmetic or logic operation is formed is: |
| A. | Address |
| B. | Accumulator |
| C. | Algorithm |
| D. | Register |
| Answer» C. Algorithm | |
| 80. |
A single phase one pulse diode rectifier is feeding an RL load with freewheeling diode across the load. For conduction angle , the main diode and free wheeling diode would, respectively conducts for: |
| A. | , ( ) |
| B. | , ( ) |
| C. | , |
| D. | ( ), |
| Answer» C. , | |
| 81. |
Which type of power supply is usually preferred for PC? |
| A. | Switched mode power supply |
| B. | Resonant power supply |
| C. | Bi-directional |
| D. | None of the above |
| Answer» B. Resonant power supply | |
| 82. |
In a power MOSFET, switching time are of the order of few |
| A. | Seconds |
| B. | Milli seconds |
| C. | Micro second |
| D. | Nono seconds |
| Answer» E. | |
| 83. |
Series connected power transistor should be |
| A. | turned on or off simultaneously |
| B. | turned on with slowest device initially |
| C. | turned off with fast device initially |
| D. | turned off or on in order of increasing transconductance |
| Answer» B. turned on with slowest device initially | |
| 84. |
The major application of chopper drive is in |
| A. | Traction |
| B. | Computers |
| C. | Heating furnaces |
| D. | Miniature motors |
| Answer» B. Computers | |
| 85. |
Which of the following regulator can provide o/p voltage more than or less than the I/P voltage? |
| A. | 1 and 2 only |
| B. | 2 and 3 only |
| C. | 3 and 4 only |
| D. | 1, 2 and 3 only |
| Answer» D. 1, 2 and 3 only | |
| 86. |
In dielectric heating. It the capacitor is loss free. The heat produced will be |
| A. | Zero |
| B. | |
| C. | Proportional to the value of capacitor |
| D. | Proportional to the frequency of capacitor |
| Answer» B. | |
| 87. |
Thermal runaway of thyristor occurs |
| A. | When the load is suddenly withdrawn |
| B. | If the temperature of thyristor is high |
| C. | In case forward anode to cathode voltage is greater than the forward breakdown voltage |
| D. | In case Gate current is high |
| Answer» C. In case forward anode to cathode voltage is greater than the forward breakdown voltage | |
| 88. |
Consider the following statements about SCR |
| A. | 1 only |
| B. | 2 only |
| C. | 2 and 3 only |
| D. | 1 and 2 only |
| Answer» D. 1 and 2 only | |
| 89. |
Silicon greases are often applied on heat sinks to |
| A. | Reduce radiation Loss |
| B. | Improve convertive heat loss |
| C. | Minimize the formation of oxides and corrosion |
| D. | To connect non-metallic parts with metallic parts |
| Answer» E. | |
| 90. |
A local storage register in the CPU which contains the address of the next instruction to be executed is called as: |
| A. | Address register |
| B. | Key register |
| C. | Register |
| D. | None of these |
| Answer» B. Key register | |
| 91. |
The cyclo converters require Natural or Forced commutation as under |
| A. | Natural communication in both step-up and step down cyclo converters |
| B. | |
| C. | Forced commutation in both step-up and step down cyclo converters |
| D. | Forced commutation in step up cyclo converters |
| E. | Forced commutation in step-down cyclo converters |
| Answer» D. Forced commutation in step up cyclo converters | |
| 92. |
In dc choppers, the wave form for |
| A. | I/p voltage is continuous and o/p voltage is discontinuous |
| B. | I/p voltage is discontinuous and o/p voltage is continuous |
| C. | I/p voltage as well as output voltage both are continuous |
| D. | I/p voltage as well as o/p voltage both are discontinuous |
| Answer» B. I/p voltage is discontinuous and o/p voltage is continuous | |
| 93. |
For thyristor, pulse triggering is preferred to d.c. triggering because |
| A. | Only statement 1 is correct |
| B. | Only statement 2 is correct |
| C. | Statements 2 and 3 are correct |
| D. | Statements 1, 2 and 3 are correct |
| Answer» E. | |
| 94. |
For a pulse transformer the material used for its care and the possible turn off ratio from primary to secondary are respectively |
| A. | Powdered iron: 1: 1 |
| B. | Laminated iron: 1: 1 |
| C. | Ferrite: 1: 1 |
| D. | Ferrite: 20: 1 |
| Answer» D. Ferrite: 20: 1 | |
| 95. |
Which of the following does not represent any directory: |
| A. | |
| B. | / |
| C. | . |
| D. | .. |
| Answer» E. | |
| 96. |
Which symbol is used for wild card: |
| A. | * |
| B. | $ |
| C. | ! |
| D. | % |
| Answer» B. $ | |
| 97. |
The blinking symbol on the computer screen is called: |
| A. | Mouse |
| B. | |
| C. | Logo |
| D. | Cursor |
| E. | Hand |
| Answer» D. Cursor | |
| 98. |
A load resistance of 10 is fed through a 1-phase voltage controller from a voltage source of 200 sin 314 t. For a firing angle delay of 90 , the power delivered to load in kW, is |
| A. | 0 5 |
| B. | 0 75 |
| C. | 1 |
| D. | 2 |
| Answer» D. 2 | |
| 99. |
A single-phase voltage controller is employed for controlling the power flow from 260 V, 50 Hz source into a load consisting of R = 5 and L = 12 . The value of maximum r.m.s. load current and the firing angle are respectively |
| A. | 20 A, 0 |
| B. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>260</center></td><td rowspan="2">A, 0 </td></tr><td align="center">10.91 </td></table> |
| C. | 20 A, 90 |
| D. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>260</center></td><td rowspan="2">A, 90 </td></tr><td align="center">10.91 </td></table> |
| Answer» B. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>260</center></td><td rowspan="2">A, 0 </td></tr><td align="center">10.91 </td></table> | |
| 100. |
A load, consisting of R = 10 and L = 10 , is being fed from 230 V, 50 Hz source through a 1-phase voltage controller. For a firing angle delay of 30 , the rms value of load current would be |
| A. | 23 A |
| B. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>23</center></td><td rowspan="2">A</td></tr><td align="center"> <span style=" text-decoration: overline;">2</span></td></table> |
| C. | <table><tr><td rowspan="2">></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>23</center></td><td rowspan="2">A</td></tr><td align="center"> <span style=" text-decoration: overline;">2</span></td></table> |
| D. | <table><tr><td rowspan="2"><</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>23</center></td><td rowspan="2">A</td></tr><td align="center"> <span style=" text-decoration: overline;">2</span></td></table> |
| Answer» C. <table><tr><td rowspan="2">></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>23</center></td><td rowspan="2">A</td></tr><td align="center"> <span style=" text-decoration: overline;">2</span></td></table> | |