MCQOPTIONS
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MCQOPTIONS
This section includes 1017 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 251. |
In a semiconductor diode, the barrier offers opposition to |
| A. | Holes in P-region only |
| B. | Free electrons in N-region only |
| C. | Majority carriers in both regions |
| D. | Majority as well as minority carriers in both regions |
| Answer» D. Majority as well as minority carriers in both regions | |
| 252. |
Assertion (A): A VMOS can handle much larger current than other field effect transistors.Reason (R): In a VMOS the conducting channel is very narrow. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» D. A is false but R is true | |
| 253. |
Assertion (A): In p-n-p transistor collector current is termed negative.Reason (R): In p-n-p transistor holes are majority carriers. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» C. A is true but R is false | |
| 254. |
Assertion (A): A JFET can be used as a current source.Reason (R): In beyond pinch off region the current in JFET is nearly constant. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 255. |
Which of the following statements regarding two transistor model of p-n-n-p device is correct? |
| A. | It explain only the turn on portion of the device characteristics |
| B. | It explain only the turn off portion of the device characteristics |
| C. | It explain only the negative region portion of the device characteristics |
| D. | It explain all the regions of the device characteristics |
| Answer» E. | |
| 256. |
Assertion (A): When p-n junction is forward biased, steady current flows. Reason (R): When a p-n junction is forward biased, free electrons cross the junction from n to p and holes from p to n. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 257. |
Breakdown in dielectric may be |
| A. | electrical breakdown |
| B. | thermal breakdown |
| C. | electrochemical breakdown |
| D. | any of the above |
| Answer» E. | |
| 258. |
Assertion (A): Oxide coated cathodes are very commonly used. Reason (R): Work function of oxide coated cathode is 1 eV whereas it is 4.5 eV for pure tungsten. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 259. |
The number of free electrons in acceptor atom is |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» D. 4 | |
| 260. |
Measurement of hall coefficient enables the determination of |
| A. | mobility of charge carriers |
| B. | type of conductivity and concentration of charge carriers |
| C. | temperature coefficient and concentration of charge carriers |
| D. | fermi level and forbidden energy gap |
| Answer» C. temperature coefficient and concentration of charge carriers | |
| 261. |
Given that the band gap of cadmium sulphide is 2.5 eV, the maximum photon wavelength, for e--hole pair generation will be |
| A. | 5400 mm |
| B. | 540 mm |
| C. | 5400 √Ö |
| D. | 540 √Ö |
| Answer» D. 540 √Ö | |
| 262. |
In fabricating silicon BJT in ICs by the epitaxial process, the number of diffusions used is usually |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 6 |
| Answer» E. | |
| 263. |
Light dependent resistors are |
| A. | highly doped semiconductor |
| B. | intrinsic semiconductor |
| C. | lightly doped semiconductor |
| D. | either (a) or (c) |
| Answer» D. either (a) or (c) | |
| 264. |
Which of the following pairs of semiconductors and current carriers is correctly matched? |
| A. | Intrinsic : number of electrons = number of holes |
| B. | P type : number of electrons > number of holes |
| C. | N type : number of electrons < number of holes |
| D. | Bulk : neither electrons nor holes |
| Answer» B. P type : number of electrons > number of holes | |
| 265. |
Electrons within a metal have energy levels from zero to Fermi level EF. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 266. |
A JFET behaves as a constant current source when |
| A. | VGS = 0 |
| B. | VGS is less than pinch off voltage |
| C. | VGS = VDS |
| D. | VGS is more than pinch off voltage |
| Answer» E. | |
| 267. |
Which of the following is used as a passive component in electronic circuits? |
| A. | Tunnel diode |
| B. | Capacitor |
| C. | Transistor |
| D. | Vacuum tube |
| Answer» C. Transistor | |
| 268. |
At room temperature a semiconductor material is |
| A. | perfect insulator |
| B. | conductor |
| C. | slightly conducting |
| D. | any of the above |
| Answer» D. any of the above | |
| 269. |
In which condition does BJT behave like a closed switch? |
| A. | Cut off |
| B. | Saturation |
| C. | Forward active |
| D. | Reverse active |
| Answer» C. Forward active | |
| 270. |
For the n-type semiconductor with n = NP and P = , the hole concentration will fall below the intrinsic value because some of the holes |
| A. | drop back to acceptor impurity states. |
| B. | drop to donor impurity states |
| C. | virtually leave the crystal |
| D. | recombine with the electrons. |
| Answer» E. | |
| 271. |
Permalloy is |
| A. | a variety of stainless steel |
| B. | a polymer |
| C. | a conon-ferrous alloy used in aircraft industry |
| D. | a nickel an iron alloy having high permeability |
| Answer» E. | |
| 272. |
The current in a p-n junction diode with V volts applied in p region relative to n region (where I0 is reverse saturation current, m is ideality factor, k is Boltzmann's constant, T is absolute temp and q is charge on electron) is |
| A. | I0 (e-qV/mkT - 1) |
| B. | I0 e-qV/mkT |
| C. | I0 (eqV/mkT) |
| D. | I0 (eqV/mkT - 1) |
| Answer» E. | |
| 273. |
Assertion (A): A high junction temperature may destroy a diode. Reason (R): As temperature increases the reverse saturation current increases. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 274. |
When the gate terminal of MOSFET is positive, it is said to operate in |
| A. | depletion mode |
| B. | conduction mode |
| C. | enhancement mode |
| D. | none of the above |
| Answer» D. none of the above | |
| 275. |
Surface leakage current is a part of |
| A. | reverse current |
| B. | forward current |
| C. | reverse breakdown |
| D. | forward breakdown |
| Answer» B. forward current | |
| 276. |
In common base configuration, the input characteristics of bipolar junction transistor are drawn between |
| A. | VEB and IE |
| B. | VCB and IC |
| C. | IC and VCE |
| D. | IE and VCE |
| Answer» B. VCB and IC | |
| 277. |
Hall coefficient is reciprocal of charge density. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 278. |
The band gap of silicon at 300K is |
| A. | 0.80 eV |
| B. | 0.67 eV |
| Answer» C. | |
| 279. |
In which device does the extent of light controls the conduction |
| A. | photovoltaic cell |
| B. | photo electric relay |
| C. | LED |
| D. | photo sensitive device |
| Answer» E. | |
| 280. |
Which of the following elements act as donor impurities? GoldPhosphorusBoronAntimonyArsenicIndium Select the correct answer using the codes given below: |
| A. | 1, 2, 3 |
| B. | 1, 2, 4, 6 |
| C. | 3, 4, 5, 6 |
| D. | 1, 4, 5 |
| Answer» E. | |
| 281. |
In case of photo conductor for germanium when forbidden energy gap is 0.72 eV, the critical wavelength for intrinsic excitation will be |
| A. | 1.43 m |
| B. | 1.43 mm |
| C. | 1.73 mm |
| D. | 1.73 x 1012 m |
| Answer» D. 1.73 x 1012 m | |
| 282. |
Which of the following devices has a silicon dioxide layer? |
| A. | NPN transistor |
| B. | Tunnel diode |
| C. | JFET |
| D. | MOSFET |
| Answer» E. | |
| 283. |
A d.c. power supply has an open circuit voltage of 100 V. When the full load current is drawn, the output drops to 80 V. The percentage voltage regulation is |
| A. | 0.9725 |
| B. | 0.75 |
| C. | 0.5 |
| D. | 0.25 |
| Answer» E. | |
| 284. |
The saturation current in a semi-conductor diode |
| A. | depends on forward voltage |
| B. | depends on reverse voltage |
| C. | is due to thermally generated minority carriers |
| D. | none of the above |
| Answer» D. none of the above | |
| 285. |
In an n channel JFET, VGS = VGS(off). Then |
| A. | ID is zero |
| B. | ID may be zero or positive |
| C. | ID is positive |
| D. | ID may be zero or negative |
| Answer» B. ID may be zero or positive | |
| 286. |
Mobility of electrons and holes are equal. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 287. |
In a N-type semi-conductor, the concentration of minority carriers is mainly depends on |
| A. | the number of acceptor atoms |
| B. | the number of donor atoms |
| C. | the extent of doping |
| D. | the temperature of the material |
| Answer» E. | |
| 288. |
Hall effect is observed in a specimen when it is carrying current and is placed in a magnetic field. The resulting electric field inside the speciment will be in |
| A. | direction antiparallel to magnetic field |
| B. | an arbitrary direction depend upon conductivity |
| Answer» B. an arbitrary direction depend upon conductivity | |
| 289. |
The work function of a photo surface whose threshold wave length is 1200 A, will be |
| A. | 0.103 eV |
| B. | 0.673 eV |
| C. | 1.03 eV |
| D. | 1.27 eV |
| Answer» D. 1.27 eV | |
| 290. |
Assertion (A): Alkali metals are used as emitters in phototubes. Reason (R): Alkali metals have low work functions. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 291. |
In p type semiconductor, the hole concentration |
| A. | is nearly equal to density of acceptor atoms |
| B. | is much greater than density of acceptor atoms |
| C. | is much less than density of acceptor atoms |
| D. | may be equal to or more or less than density of acceptor atoms |
| Answer» B. is much greater than density of acceptor atoms | |
| 292. |
For a photo conductor with equal electron and hole mobilities and perfect ohmic contacts at the ends, an increase in the intensities of optical illumination results in |
| A. | change in open circuit voltage |
| B. | change in short circuit current |
| C. | a reduction resistance |
| D. | an increase of resistance |
| Answer» D. an increase of resistance | |
| 293. |
The units for transconductance are |
| A. | ohms |
| B. | amperes |
| C. | volts |
| D. | siemens |
| Answer» E. | |
| 294. |
NAME? |
| A. | reduce bandwidth |
| B. | increase noise |
| Answer» B. increase noise | |
| 295. |
Choose the correct match for input resistance of various amplifier configurations shown below configuration.CB : Common Base LO : LowCC : Common Collector ‚ÄÇMO : moderateCE : Common EmitterHI: High |
| A. | CB-LO, CC-MO, CE-HI |
| B. | CB-LO, CC-HI, CE-MO |
| C. | CB-MO, CC-HI, CE-LO |
| D. | CB-HI, CC-LO, CE-MO |
| Answer» C. CB-MO, CC-HI, CE-LO | |
| 296. |
Light dependent resistor is |
| A. | photo resistive device |
| B. | photo voltaic device |
| C. | photo emissive device |
| D. | either (a) or (c) |
| Answer» B. photo voltaic device | |
| 297. |
If E (i.e., available energy state) = EF(i.e., Fermi level), then probability that state E will be occupied is 0.5 for any temperature T. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 298. |
Compared to bipolar junction transistor, a JFET has |
| A. | lower input impedance |
| B. | high input impedance and high voltage gain |
| C. | higher voltage gain |
| D. | high input impedance and low voltage gain |
| Answer» E. | |
| 299. |
The first dominant pole encountered in the frequency response of a compensated op-amp is approximately at |
| A. | 5 Hz |
| B. | 10 kHz |
| C. | 1 MHz |
| D. | 100 MHz |
| Answer» B. 10 kHz | |
| 300. |
Consider the following statement associated with bipolar junction transistor and JFET The former has higher input impedance than the laterThe former has higher frequency stability than the laterThe later has lower noise figure than the formerThe later has higher power rating than the former. Of these statements |
| A. | 3 and 4 are correct |
| B. | 1 and 4 are correct |
| Answer» C. | |