MCQOPTIONS
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MCQOPTIONS
This section includes 335 Mcqs, each offering curated multiple-choice questions to sharpen your Power Electronics knowledge and support exam preparation. Choose a topic below to get started.
| 301. |
The gate characteristics of thyristor is a plot of |
| A. | Vg on the X-axis & Ig on the Y-axis |
| B. | Ig on the X-axis & Vg on the Y-axis |
| C. | Va on the X-axis & Ig on the Y-axis |
| D. | Ig on the X-axis & Va on the Y-axis |
| Answer» C. Va on the X-axis & Ig on the Y-axis | |
| 302. |
Latching current for an SCR is 100 mA, a dc source of 200 V is also connected to the SCR which is supplying an R-L load. Compute the minimum width of the gate pulse required to turn on the device. Take L = 0.2 H & R = 20 ohm both in series. |
| A. | 62.7 μsec |
| B. | 100.5 μsec |
| C. | 56.9 μsec |
| D. | 81 μsec |
| Answer» C. 56.9 μsec | |
| 303. |
To avoid commutation failure |
| A. | circuit turn-off time must be greater than the thyristor turn-off time |
| B. | circuit turn-off time must be lesser than the thyristor turn-off time |
| C. | circuit turn-off time must be equal to the thyristor turn-off time |
| D. | none of the above mentioned |
| Answer» B. circuit turn-off time must be lesser than the thyristor turn-off time | |
| 304. |
The SITH has |
| A. | gate, anode, cathode |
| B. | base, collector, emitter |
| C. | base, anode, cathode |
| D. | gate, emitter, collector |
| Answer» B. base, collector, emitter | |
| 305. |
The TRIAC's terminals are |
| A. | gate, anode, cathode |
| B. | MT1, MT2, gate |
| C. | gate1, gate2, anode, cathode |
| D. | MT1, MT2, gate1, gate2 |
| Answer» C. gate1, gate2, anode, cathode | |
| 306. |
In the transfer characteristics of a MOSFET, the threshold voltage is the measure of the |
| A. | minimum voltage to induce a n-channel/p-channel for conduction |
| B. | minimum voltage till which temperature is constant |
| C. | minimum voltage to turn off the device |
| D. | none of the above mentioned is true |
| Answer» B. minimum voltage till which temperature is constant | |
| 307. |
For an SCR the total turn-on time consists ofi) Delay timeii) Rise time andiii) Spread timeDuring the rise time the |
| A. | anode current flows only near the gate |
| B. | anode current rises from zero to very high value |
| C. | losses are maximum |
| D. | anode to cathode voltage is zero |
| Answer» D. anode to cathode voltage is zero | |
| 308. |
Heat dissipation from heat sink mainly takes place by |
| A. | radiation |
| B. | convection |
| C. | absorption |
| D. | none of the mentioned |
| Answer» C. absorption | |
| 309. |
In case of the two-transistor model (T1 & T2) of GTO with anode-short, the anode-short is placed between the |
| A. | emitter of T1 & T2 |
| B. | emitter of T1 & base of T2 |
| C. | emitter of T1 & base of T1 |
| D. | emitter of T1 & collector of T2 |
| Answer» D. emitter of T1 & collector of T2 | |
| 310. |
For MOSFET's SOA, as the pulse width goes on increasing, the maximum voltage rating ____ & current rating ____ |
| A. | is constant, increases |
| B. | increases, decreases |
| C. | decreases, is constant |
| D. | constant, decreases |
| Answer» D. constant, decreases | |
| 311. |
The controlled parameter in IGBT is the |
| A. | IG |
| B. | VGE |
| C. | IC |
| D. | VCE |
| Answer» D. VCE | |
| 312. |
The SOA for an IGBT is plotted for |
| A. | Ic versus Vge |
| B. | Ig versus Ic |
| C. | Ig versus Vce |
| D. | Ic versus Vce |
| Answer» E. | |
| 313. |
The thermal resistance between junction & the SCR (θjc) has the unit |
| A. | Ω/°C |
| B. | W/Ω |
| C. | °C/W |
| D. | ΩW/°C |
| Answer» D. ΩW/°C | |
| 314. |
For low power SCRs (about 1 Ampere current) _____________ type of mounting is used |
| A. | lead |
| B. | stud |
| C. | bolt-down |
| D. | press-fit |
| Answer» B. stud | |
| 315. |
A power BJT is used as a power control switch by biasing it in the cut off region (off state) or in the saturation region (on state). In the on state |
| A. | both the base-emitter & base-collector junctions are forward biased |
| B. | the base-emitter junction is reverse biased, and the base collector junction is forward biased |
| C. | the base-emitter junction is forward biased, and the base collector junction is reversed biased |
| D. | both the base-collector & the base-emitter junctions are reversed biased |
| Answer» B. the base-emitter junction is reverse biased, and the base collector junction is forward biased | |
| 316. |
The SITH will act as a diode when the |
| A. | anode is forward biased with zero gate-cathode voltage |
| B. | anode is reversed biased with zero gate-cathode voltage |
| C. | anode is forward biased and a positive gate voltage is applied |
| D. | anode is forward biased and a negative gate voltage is applied |
| Answer» B. anode is reversed biased with zero gate-cathode voltage | |
| 317. |
For an SCR in the reverse blocking mode, (practically) |
| A. | leakage current does not flow |
| B. | leakage current flows from anode to cathode |
| C. | leakage current flows from cathode to anode |
| D. | leakage current flows from gate to anode |
| Answer» D. leakage current flows from gate to anode | |
| 318. |
The turn-off gain βoff of the GTO is given by |
| A. | Ig/Ia |
| B. | Ia/Ig |
| C. | Vg/Va |
| D. | Vg/Va |
| Answer» C. Vg/Va | |
| 319. |
The body of an IGBT consists of a |
| A. | p-layer |
| B. | n-layer |
| C. | p-n layer |
| D. | metal |
| Answer» B. n-layer | |
| 320. |
In the reverse blocking mode the middle junction (J2) has the characteristics of that of a |
| A. | transistor |
| B. | capacitor |
| C. | inductor |
| D. | none of the mentioned |
| Answer» C. inductor | |
| 321. |
SCRs with a rating of 1000 V & 200 A are available to be used in a string to handle 6 KV & 1 KV. Calculate the number of series & parallel units required in case the de-rating factor is 0.1. (Round off the fraction to the greatest & nearest integer) |
| A. | Series = 7, Parallel = 6 |
| B. | Series = 6, Parallel = 7 |
| C. | Series = 6, Parallel = 6 |
| D. | Series = 7, Parallel = 7 |
| Answer» B. Series = 6, Parallel = 7 | |
| 322. |
________ are semiconductor thyristor devices which can be turned-on by light of appropriate wavelengths. |
| A. | LGTOs |
| B. | LASERs |
| C. | MASERs |
| D. | LASCRs |
| Answer» E. | |
| 323. |
The N-channel MOSFET is considered better than the P-channel MOSFET due to its |
| A. | low noise levels |
| B. | TTL compatibility |
| C. | lower input impedance |
| D. | faster operation |
| Answer» E. | |
| 324. |
For a SCR the maximum rms on-state current is 35 A. If the SCR is used in a resistive circuit for a rectangular wave with conduction angle of 90°. Calculate the average & rms currents respectively. |
| A. | I/4, I/2 |
| B. | I/2, I/√2 |
| C. | I/4, I2/2 |
| D. | I/4, I/√2 |
| Answer» B. I/2, I/√2 | |
| 325. |
The basic advantage of the CMOS technology is that |
| A. | It is easily available |
| B. | It has small size |
| C. | It has lower power consumption |
| D. | It has better switching capabilities |
| Answer» D. It has better switching capabilities | |
| 326. |
The TRIAC can be represented by |
| A. | two SCRs in anti-parallel |
| B. | two SCRs in parallel |
| C. | two diodes in anti-parallel |
| D. | two diodes in parallel |
| Answer» B. two SCRs in parallel | |
| 327. |
For an SCR, the gate-cathode characteristic has a slop of 130. The gate power dissipation is 0.5 watts. Find Ig |
| A. | 0.62 A |
| B. | 620 mA |
| C. | 62 mA |
| D. | 6.2 mA |
| Answer» D. 6.2 mA | |
| 328. |
Choose the correct statement:GTOs have _________ as compared to the CTs. |
| A. | less on-state voltage drop |
| B. | less gate drive losses |
| C. | higher reverse blocking capabilities |
| D. | faster switching speed |
| Answer» E. | |
| 329. |
The structure of the IGBT is a |
| A. | P-N-P structure connected by a MOS gate |
| B. | N-N-P-P structure connected by a MOS gate |
| C. | P-N-P-N structure connected by a MOS gate |
| D. | N-P-N-P structure connected by a MOS gate |
| Answer» D. N-P-N-P structure connected by a MOS gate | |
| 330. |
The forward current gain α is given by |
| A. | IC/IB |
| B. | IC/IE |
| C. | IE/IC |
| D. | IE/IB |
| Answer» C. IE/IC | |
| 331. |
In SITH, the magnitude of the anode current can be controlled by |
| A. | controlling the anode-cathode voltage |
| B. | controlling the negative gate bias |
| C. | controlling the positive gate bias |
| D. | it cannot be controlled |
| Answer» C. controlling the positive gate bias | |
| 332. |
Choose the correct statement(s) i) The gate circuit impedance of MOSFET is higher than that of a BJT ii) The gate circuit impedance of MOSFET is lower than that of a BJTiii) The MOSFET has higher switching losses than that of a BJT iv) The MOSFET has lower switching losses than that of a BJT |
| A. | Both i & ii |
| B. | Both ii & iv |
| C. | Both i & iv |
| D. | Only ii |
| Answer» D. Only ii | |
| 333. |
Consider the two transistor analogy of SCR, if α1 & if α2 are the common-base current gains of both the transistors then to turn-on the device |
| A. | α1 + α2 should approach zero |
| B. | α1 x α2 should approach unity |
| C. | α1 – α2 should approach zero |
| D. | α1 + α2 should approach unity |
| Answer» E. | |
| 334. |
The TRIAC is most sensitive in the _________ quadrants |
| A. | 1st & 3rd with positive gate current |
| B. | 1st with positive gate current & 3rd with negative gate current |
| C. | 3st with positive gate current & 1rd with negative gate current |
| D. | 1st & 3rd with negative gate current |
| Answer» C. 3st with positive gate current & 1rd with negative gate current | |
| 335. |
Latching current for the GTOs is ________ as compared to CTs (Conventional thyristors). |
| A. | more |
| B. | less |
| C. | constant |
| D. | cannot be said |
| Answer» B. less | |