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.
| 301. |
If 1 kVA transformer is used for all of the following rectifiers, the d.c. power availability will be least in case of |
| A. | half wave rectifier |
| B. | full wave rectifier |
| C. | bridge rectifier |
| D. | three phase full wave rectifier |
| Answer» E. | |
| 302. |
Which of the following semiconductor has the highest melting point? |
| A. | Germanium |
| B. | Silicon |
| C. | Gallium arsenide |
| D. | Lead sulphide |
| Answer» E. | |
| 303. |
The resistivity of intrinsic semiconductor material is about |
| A. | 105 ohm-m |
| B. | 103 ohm-m |
| C. | 100 ohm-m |
| D. | 1 ohm-m |
| Answer» E. | |
| 304. |
The conductivity of an intrinsic semiconductor is |
| A. | generally less than that of a doped semiconductor |
| B. | given by σ1 = eni (μn - μp) |
| C. | given by σ1 = eni (μp + μn) |
| D. | given by σ1 = ni (μn + μp) |
| Answer» D. given by œÉ1 = ni (Œºn + Œºp) | |
| 305. |
Assertion (A): The resistivity of intrinsic semiconductor decreases with increase in temperature. Reason (R): The forbidden gap decreases with increase in temperature. |
| 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 | |
| 306. |
In degenerate p type semiconductor material, the Fermi level, |
| A. | is at the centre in between valence and conduction bands |
| B. | is very near conduction band |
| Answer» B. is very near conduction band | |
| 307. |
For an n-channel JEFT having drain source voltage constant if the gate source voltage is increased (more negative) pinch off would occur for |
| A. | high values of drain current |
| B. | saturation values of drain current |
| C. | zero drain current |
| D. | gate current equal to the drain current |
| Answer» D. gate current equal to the drain current | |
| 308. |
In a piezoelectric crystal, applications of a mechanical stress would produce |
| A. | plastic deformation of the crystal |
| B. | magnetic dipoles in the crystal |
| C. | electrical polarization in the crystal |
| D. | shift in the Fermi level |
| Answer» D. shift in the Fermi level | |
| 309. |
An insulator will conduct when the |
| A. | voltage applied is more than the breakdown voltage |
| B. | temperature is raised to very high level |
| C. | either (a) or (b) above |
| D. | none of the above |
| Answer» D. none of the above | |
| 310. |
Electromagnetic waves transport |
| A. | energy only |
| B. | momentum only |
| C. | energy as well as momentum |
| D. | neither energy nor momentum |
| Answer» D. neither energy nor momentum | |
| 311. |
When reverse bias is applied to a junction diode |
| A. | minority carrier current is increased |
| B. | majority carrier current is increased |
| C. | potential barrier is lowered |
| D. | potential barrier is raised |
| Answer» E. | |
| 312. |
An electron rises through a voltage of 100 V. The energy acquired by it will be |
| A. | 100 eV |
| B. | 100 joules |
| C. | (100)1.2 eV |
| D. | (100)1.2 joules |
| Answer» B. 100 joules | |
| 313. |
In common base connection, the output characteristics of a bipolar junction transistor is drawn between |
| A. | IC and VCB |
| B. | IC and VCE |
| C. | IE and VCB |
| D. | IE and VCE |
| Answer» B. IC and VCE | |
| 314. |
For a BJT, avalanche multiplication factor depends on |
| A. | VBE |
| B. | none |
| C. | gallium |
| D. | indium |
| Answer» C. gallium | |
| 315. |
Assertion (A): A JFET behaves as a resistor when VGS < VP. Reason (R): When VGS < VP, the drain current in a JFET is almost constant. |
| A. | A is true but R is false |
| B. | A is false but R is true |
| C. | zero voltage |
| D. | 1.2 V |
| Answer» D. 1.2 V | |
| 316. |
Forbidden energy gap in germanium at 0 K is about |
| A. | 10 eV |
| B. | 5 eV |
| C. | 2 eV |
| D. | 0.78 eV |
| Answer» E. | |
| 317. |
Donor energy level is n type semiconductor is very near valence band. |
| A. | 1 |
| B. | |
| C. | visible region of the spectrum |
| D. | infrared region of the spectrum |
| Answer» C. visible region of the spectrum | |
| 318. |
Which of the following material is preferred for transformer cores operating in micro wave frequency range? |
| A. | Ferrites |
| B. | Silicon steel |
| C. | Superalloy |
| D. | Copper |
| Answer» B. Silicon steel | |
| 319. |
Assertion (A): In a BJT base current is very small. Reason (R): In a BJT recombination in base region is high. |
| 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 | |
| 320. |
Covalent bond energy in Germanium is approximately |
| A. | 3.8 eV |
| B. | 4.7 eV |
| C. | 7.4 eV |
| D. | 12.5 eV |
| Answer» D. 12.5 eV | |
| 321. |
For a n-channel JFET with r0 = 10 kW, (VGs= 0 V, VP = - 6 V)the drain resistance rd at VGS= - 3 V is given by |
| A. | 40 kΩ |
| B. | 2.5 kΩ |
| C. | 4.44 kW |
| D. | 120 kW |
| Answer» B. 2.5 kŒ© | |
| 322. |
The conductivity of a semiconductor crystal due to any current carrier is not proportional to |
| A. | electronic charge |
| B. | surface states in the semiconductor |
| C. | the applied voltage |
| D. | the temperature |
| Answer» B. surface states in the semiconductor | |
| 323. |
Free electrons exist in |
| A. | first band |
| B. | second band |
| C. | third band |
| D. | conduction band |
| Answer» E. | |
| 324. |
In intrinsic semiconductor at 300 K, the magnitude of free electron concentration in silicon is about |
| A. | 15 x 104 per cm3 |
| B. | 5 x 1012 per cm3 |
| C. | 1.45 x 1010 per cm3 |
| D. | 1.45 x 106 per cm3 |
| Answer» D. 1.45 x 106 per cm3 | |
| 325. |
For radiating ultraviolet rays, LEDs use |
| A. | zinc sulphide |
| B. | gallium arsenide |
| C. | gallium phosphide |
| D. | none of the above |
| Answer» B. gallium arsenide | |
| 326. |
Germanium and Si phosphorus have their maximum spectral response in the |
| A. | infrared region |
| B. | ultraviolet region |
| C. | visible region |
| D. | X-ray region |
| Answer» C. visible region | |
| 327. |
In a triode the potential of grid (with respect to cathode) is usually |
| A. | zero |
| B. | negative |
| C. | positive |
| D. | zero or positive |
| Answer» C. positive | |
| 328. |
Assertion (A): FET is a unipolar device. Reason (R): BJT is bipolar device. |
| 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 | |
| 329. |
The current gain of a transistor is the ratio of |
| A. | emitter current to base current |
| B. | emitter current to collector current |
| C. | collector current to base current |
| D. | collector current to emitter current |
| Answer» D. collector current to emitter current | |
| 330. |
In a P type silicon sample, the hole concentration is 2.25 x 1015 / cm3. If the intrinsic carrier concentration is 1.5 x 1010/ cm3 the electron concentration is |
| A. | zero |
| B. | 1010/cm3 |
| C. | 105/cm3 |
| D. | 1.5 x 1025/cm3 |
| Answer» D. 1.5 x 1025/cm3 | |
| 331. |
Silicon is not suitable for fabrication of light emitting diodes because it is |
| A. | an indirect band gap semiconductor |
| B. | direct band gap semiconductor |
| C. | wideband gap semiconductor |
| D. | narrowband gap semiconductor |
| Answer» B. direct band gap semiconductor | |
| 332. |
The rating of a transformer to deliver 100 watts of D.C. power to a load under half wave rectifier will be nearly |
| A. | 1 kVA |
| B. | 350 VA |
| C. | 175 VA |
| D. | 108 VA |
| Answer» C. 175 VA | |
| 333. |
Due to the formation of Schottky defects the density of the crystal |
| A. | decreases slightly |
| B. | decreases appreciably |
| C. | 1.36 eV |
| D. | 1.10 eV |
| Answer» D. 1.10 eV | |
| 334. |
Assertion (A): FET has characteristics very similar to that of pentode. Reason (R): Both FET and pentode are voltage controlled devices. |
| 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 | |
| 335. |
The depletion layer around p-n junction in JFET consists of |
| A. | immobile charges |
| B. | none of the above |
| C. | 1 |
| D. | |
| Answer» D. | |
| 336. |
Which of the following statement about the photo electric emission is incorrect? |
| A. | The maximum velocity of emission varies with the frequency of incident light |
| B. | The maximum velocity of emission varies with the intensity of light |
| C. | The amount of photoelectric emission is directly proportional to the intensity of light |
| D. | The quantum yield depends on the frequency and not the intensity of incident light |
| Answer» C. The amount of photoelectric emission is directly proportional to the intensity of light | |
| 337. |
Operating point signifies that |
| A. | zero signal IC and VBE |
| B. | zero signal IC and VCE |
| C. | zero signal IB and VCE |
| D. | zero signal IC, VCE |
| Answer» C. zero signal IB and VCE | |
| 338. |
Consider the following circuit configuration common Emittercommon Baseemitter followeremitter follower using Darlington pair. The correct sequence in increasing order of I/P impedance of these configuration: |
| A. | 2, 1, 3, 4 |
| B. | 1, 2, 3, 4 |
| C. | Both A and R are true and R is correct explanation of A |
| D. | Both A and R are true but R is not a correct explanation of A |
| Answer» C. Both A and R are true and R is correct explanation of A | |
| 339. |
In intrinsic semiconductor the increase in conductivity per degree increase in temperature is about |
| A. | 0.02 |
| B. | 0.06 |
| C. | 0.15 |
| D. | 0.25 |
| Answer» C. 0.15 | |
| 340. |
Assertion (A): When VDS is more than rated value the drain current in a JFET is very high. Reason (R): When VDS is more than rated value, avalanche breakdown occurs. |
| A. | A is true but R is false |
| B. | A is false but R is true |
| C. | 0.5 and 1 |
| D. | - 2 and 1 |
| Answer» B. A is false but R is true | |
| 341. |
Which of these is also called 'hot carrier diode'? |
| A. | PIN diode |
| B. | LED |
| C. | Photo diode |
| D. | Schottky diode |
| Answer» E. | |
| 342. |
Ferromagnetic materials exhibit |
| A. | a linear B-H behaviour |
| B. | a non-linear B-H behaviour |
| C. | an exponential B-H behaviour |
| D. | none of the above |
| Answer» C. an exponential B-H behaviour | |
| 343. |
When electronic emission occurs due to bombardment of high velocity electrons on a metal surface, it is called secondary emission. |
| A. | 1 |
| B. | |
| C. | 1 |
| D. | |
| Answer» B. | |
| 344. |
If an additional two diodes were used to connect the 1 kW load across a bridge rectifier circuits, utilizing the full secondary of the transformer, how much d.c. power could be delivered using a transformer with the rating of 105 VA? |
| A. | 35 W |
| B. | 60 W |
| C. | 85 W |
| D. | 100 W |
| Answer» D. 100 W | |
| 345. |
For signal diodes the PIV rating is usually in the range |
| A. | 1 V to 10V |
| B. | 10 V to 30V |
| C. | 30 V to 150V |
| D. | 150 V to 400V |
| Answer» D. 150 V to 400V | |
| 346. |
Semiconductors have |
| A. | aero temperature coefficient of resistance |
| B. | positive temperature coefficient of resistance |
| C. | negative temperature coefficient of resistance |
| D. | none of the above |
| Answer» D. none of the above | |
| 347. |
In which n type device does p substrate extend upto silicon dioxide layer? |
| A. | JFET |
| B. | Depletion type MOSFET |
| C. | Enhancement type MOSFET |
| D. | Both (b) and (c) |
| Answer» D. Both (b) and (c) | |
| 348. |
Assertion (A): The frequency of light used for photoelectric emission is high. Reason (R): As per Einstein's equation 0.5 mv2 < hf - Uw. |
| 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 | |
| 349. |
In a P-type semiconductor, the conductivity due to holes (= σP) is equal to e = charge of hole, μP = hole mobility, P = hole concentration, |
| A. | P.e.μP |
| B. | |
| C. | direction normal to both current and magnetic field |
| Answer» D. | |
| 350. |
Which one of the following bipolar transistors has the highest current gain bandwidth Product (fr) for similar geometry? |
| A. | NPN germanium transistor |
| B. | NPN silicon transistor |
| C. | PNP germanium transistor |
| D. | PNP silicon transistor |
| Answer» C. PNP germanium transistor | |