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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.
| 451. |
The addition of p type impurity to intrinsic material creates allowable energy levels. |
| A. | slightly below conduction band |
| B. | slightly above conduction band |
| C. | slightly below valence band |
| D. | slightly above valence band |
| Answer» E. | |
| 452. |
Amplification of ultrasonic waves is possible in a piezoelectric semiconductor under applied electric field. The basic phenomenon involved is known as |
| A. | electrostriction |
| B. | acousto-optic interaction |
| C. | acousto-electric interaction |
| D. | stimulated Brillouin scattering |
| Answer» D. stimulated Brillouin scattering | |
| 453. |
The conductivity of an intrinsic semiconductor is (symbols have the usual meanings). |
| A. | generally less than that a doped semiconductor |
| B. | σi = eni (μn - μp) |
| C. | σi = eni (μn + μp) |
| D. | σi = ni (μn - μp) |
| Answer» D. œÉi = ni (Œºn - Œºp) | |
| 454. |
Consider the following statements. EtchingExposure to UV radiationStrippingDeveloping After a wafer has been coated with photo resist the correct sequence of these steps in photolithography is |
| A. | 2, 4, 3, 1 |
| B. | 2, 4, 1, 3 |
| C. | 4, 2, 1, 3 |
| D. | 3, 2, 3, 1 |
| Answer» D. 3, 2, 3, 1 | |
| 455. |
In the vacuum diode equation ib = keb1.5, the current is |
| A. | temperature limited current |
| B. | space charge limited current |
| C. | any of the above |
| D. | none of the above |
| Answer» C. any of the above | |
| 456. |
If 10 V is the peak voltage across the secondary of the transformer in a half wave rectifier (without any filter circuit), then the maximum voltage on the reverse biased diode will be |
| A. | 20 V |
| B. | 14.14 V |
| C. | 10 V |
| D. | 7.8 V |
| Answer» D. 7.8 V | |
| 457. |
Gold is often diffused into silicon PN junction devices to |
| A. | increase the recombination rate |
| B. | reduce the recombination rate |
| C. | make silicon a direct gap semiconductor |
| D. | make silicon semimetal |
| Answer» D. make silicon semimetal | |
| 458. |
With increasing temperature, the electrical conductivity of metals |
| A. | increases |
| B. | decreases |
| C. | increases first and then decreases |
| D. | remains unaffected |
| Answer» C. increases first and then decreases | |
| 459. |
Hall effect is observed in a specimen when it is carrying current and is placed in a magnetic field. The resultant electric field inside the specimen is |
| A. | normal to both current and magnetic field |
| B. | in the direction of current |
| C. | antiparallel to magnetic field |
| D. | in arbitrary direction |
| Answer» B. in the direction of current | |
| 460. |
In an n type semiconductor the fermi level is 0.35 eV below the conduction band, the concentration of donor atoms is increased to three times. The new position of Fermi level will be |
| A. | about 0.32 eV above conduction band |
| B. | about 0.1 eV below conduction band |
| 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 | |
| 461. |
When a P-N junction is unbiased, the junction current at equilibrium is |
| A. | zero as no charges cross the junction |
| B. | zero as equal number of carriers cross the barrier |
| C. | mainly due to diffusion of majority carriers |
| D. | mainly due to diffusion of minority carriers |
| Answer» C. mainly due to diffusion of majority carriers | |
| 462. |
Which of the following diode is designed to operate in the breakdown region? |
| A. | Signal diode |
| B. | Power diode |
| C. | Zener diode |
| D. | None of the above |
| Answer» D. None of the above | |
| 463. |
N-type silicon is obtained by doping silicon with |
| A. | germanium |
| B. | aluminium |
| C. | boron |
| D. | phosphorus |
| Answer» E. | |
| 464. |
The maximum forward current in case of signal diode is in the range of |
| A. | few milli amperes |
| B. | few nano amperes |
| C. | Thomson effect |
| D. | Seeback effect |
| Answer» D. Seeback effect | |
| 465. |
In a full wave rectifier, the current in each of the diodes flows for |
| A. | the complete cycle of the input signal |
| B. | half cycle of the input signal |
| C. | less than half cycle of the input signal |
| D. | one-fourth cycle of the input signal |
| Answer» C. less than half cycle of the input signal | |
| 466. |
The O/P Power of a power amplifier is several times its input power. It is possible because |
| A. | power amplifier introduces a -ve resistance |
| B. | there is +ve feed back in the circuit |
| C. | step up transformer is use in the circuit |
| D. | power amplifier converts a part of I/P d.c. power into a.c. power |
| Answer» E. | |
| 467. |
Assertion (A): Silicon is less sensitive to changes in temperature than germanium. Reason (R): It is more difficult to produce minority carriers in silicon than in germanium. |
| 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 | |
| 468. |
For an P-N-P transistor in normal operation its junction are biased as |
| A. | emitter base : reverse, collector base : forward |
| B. | emitter base : forward, collector base : reverse |
| C. | emitter base : forward, collector base : forward |
| D. | emitter base : reverse, collector base : reverse |
| Answer» C. emitter base : forward, collector base : forward | |
| 469. |
At any point on the v-i characteristics of a semiconductor diode, the slope of v-i characteristics is called |
| A. | resistance of diode |
| B. | conductance of diode |
| C. | incremental resistance of diode |
| D. | incremental conductance of diode |
| Answer» E. | |
| 470. |
Assertion (A): Power transistors are more commonly of silicon npn type. Reason (R): The fabrication of silicon npn transistors is easy. |
| 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 | |
| 471. |
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 | |
| 472. |
Hall's effect can be used to measure |
| A. | magnetic field intensity |
| B. | average number of holes |
| C. | carriers concentration |
| D. | electrostatic field intensity |
| Answer» B. average number of holes | |
| 473. |
When a semi-conductor is doped, its electrical conductivity |
| A. | increases |
| B. | decreases in the direct ratio of the doped material |
| C. | decreases in the inverse ratio of the doped material |
| D. | remains unaltered |
| Answer» B. decreases in the direct ratio of the doped material | |
| 474. |
The kinetic energy of free electrons in a metal is (where k is de-Broglie wave number of the electrons) |
| A. | ‚àù |
| B. | ‚àù |
| C. | μk |
| D. | μk2 |
| Answer» C. Œºk | |
| 475. |
An intrinsic silicon sample has 2 million free electrons. The number of holes in the sample is |
| A. | 2 million |
| B. | almost zero |
| C. | more than 2 million |
| D. | less than 2 million |
| Answer» B. almost zero | |
| 476. |
With an ac input from 50 Hz power line, the ripple frequency is |
| A. | 50 Hz in the dc output of half wave as well as full wave rectifier |
| B. | 100 Hz in the dc output of half wave as well as full wave rectifier |
| C. | 50 Hz in the dc output of half wave and 100 Hz in the dc output of full wave |
| D. | 100 Hz in the dc output of half wave and 50 Hz in the dc output of full wave |
| Answer» D. 100 Hz in the dc output of half wave and 50 Hz in the dc output of full wave | |
| 477. |
The amount of time between the creation and disappearance of a hole in an intrinsic semiconductor material is called |
| A. | life cycle |
| B. | recombination time |
| C. | life time |
| D. | half life |
| Answer» D. half life | |
| 478. |
What is meant by "continuous collector current" in BJT? |
| A. | Maximum collector current |
| B. | Current at Quiescent condition |
| C. | Leakage current |
| D. | Junction Capacitance charging and discharging current |
| Answer» B. Current at Quiescent condition | |
| 479. |
In a photo transistor the photocurrent is |
| A. | collector |
| B. | either (a) or (b) |
| C. | f |
| D. | f |
| Answer» C. f | |
| 480. |
For a photoengraving the mask used is |
| A. | master mask |
| B. | slave mask |
| C. | working mask |
| D. | photo mask |
| Answer» D. photo mask | |
| 481. |
A potential difference is developed across a current carrying metal strip when the strip is placed in a transverse magnetic field. The above effect is known as |
| A. | Fermi's effect |
| B. | Photo electric effect |
| C. | Joule's effect |
| D. | Hall's effect |
| Answer» E. | |
| 482. |
The intrinsic resistivity of silicon at 300 K is about |
| A. | 1 Ω-cm |
| B. | 400 Ω-cm |
| C. | 10000 Ω-cm |
| D. | 230000 Ω-cm |
| Answer» E. | |
| 483. |
The ratio of diffusion constant for hole DP to the mobility for holes is proportional to |
| A. | T2 |
| B. | T |
| C. | 1/T |
| D. | T3 |
| Answer» C. 1/T | |
| 484. |
Which of the following element has four valence electrons? |
| A. | Silicon |
| B. | Germanium |
| C. | Both (a) and (b) above |
| D. | None of the above |
| Answer» D. None of the above | |
| 485. |
As comparated to an ordinary p-n diode, the extent of impurity atoms in a tunnel diode |
| A. | is more |
| B. | is less |
| C. | may be more or less |
| D. | is almost the same |
| Answer» B. is less | |
| 486. |
If the reverse voltage across a p-n junction is increased three times, the junction capacitance |
| A. | will decrease |
| B. | will increase |
| C. | will decrease by an approximate factor of about 2 |
| D. | will increase by an approximate factor of about 2 |
| Answer» D. will increase by an approximate factor of about 2 | |
| 487. |
Assertion (A): A BJT can be used as a switch. Reason (R): In forward active mode emitter base junction is forward biased and base collector junction is reverse biased. |
| 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 | |
| 488. |
Between which regions does BJT act like switch? |
| A. | Cut off and saturation |
| B. | Cut off and forward active |
| C. | Forward active and cut off |
| D. | Saturation and active |
| Answer» B. Cut off and forward active | |
| 489. |
The concentration of minority carriers in a semiconductor depends mainly on |
| A. | the extent of doping |
| B. | temperature |
| C. | the applied bias |
| D. | none of the above |
| Answer» C. the applied bias | |
| 490. |
In an insulated gate FET, the polarity of inversion layer is the same as that of |
| A. | minority carriers in source |
| B. | majority carriers in source |
| C. | charge on gate electrode |
| D. | minority carriers in drain |
| Answer» C. charge on gate electrode | |
| 491. |
For a semiconductor, the conductivity is a function of the products of the number of charge carriers and their mobilites. As result, if the temperature of a slab of intrinsic silicon increases, how does its conductivity vary? |
| A. | Decreases |
| B. | Increases |
| C. | Remains unaffected |
| D. | Increases or decreases depending upon the rise in temperature |
| Answer» C. Remains unaffected | |
| 492. |
The most important set of specifications of transformer oil includes |
| A. | dielectric strength and viscosity |
| B. | dielectric strength and flash point |
| C. | flash point and viscosity |
| D. | dielectric strength, flash point and viscosity |
| Answer» E. | |
| 493. |
For a full wave bridge rectifier supplied with 50 Hz a.c., the lowest ripple frequency will be |
| A. | 50 Hz |
| B. | 100 Hz |
| C. | 200 Hz |
| D. | 400 Hz |
| Answer» C. 200 Hz | |
| 494. |
In a photo emissive device and emission efficiency is increased by |
| A. | coating the cathode ray by an active materials |
| B. | coating the cathode by an insulating material |
| C. | heating the cathode |
| D. | cooling the anode |
| Answer» B. coating the cathode by an insulating material | |
| 495. |
Typical values of h parameters at about 1 mA collector current for small signal audio amplifier in CE configuration are : |
| A. | hie = 100 Ω, hre = 10-1, hfe = 50, hoe = 1 m mho |
| B. | hie = 5 kΩ, hre = 10-4, hfe = 200, hoe = 20 m mho |
| C. | hie = 5 kΩ, hre = 0, hfe = 50, hoe = 2 m mho |
| D. | hie = 100 kΩ, hre = 10-2, hfe = 100, hoe = 10 m mho |
| Answer» C. hie = 5 kŒ©, hre = 0, hfe = 50, hoe = 2 m mho | |
| 496. |
Photo electric emission can occur only if |
| A. | wave length of incident radiation is equal to threshold value |
| B. | wave length of incident radiation is less than threshold value |
| C. | frequency of incident radiation is less than threshold frequency |
| D. | none of the above |
| Answer» C. frequency of incident radiation is less than threshold frequency | |
| 497. |
Assertion (A): Germanium is more commonly used than silicon. Reason (R): Forbidden gap in germanium is less than that in silicon. |
| A. | A is true but R is false |
| B. | A is false but R is true |
| C. | JFET |
| D. | Depletion Type MOSFET |
| Answer» E. | |
| 498. |
The ripple factor from a capacitor filter __________ as the load resistance __________ . |
| A. | decreases, decreases |
| B. | decreases, increases |
| C. | increases, decreases |
| D. | increases, increases |
| Answer» C. increases, decreases | |
| 499. |
If μn is mobility of free electron and μp is mobility of holes then for silicon at 300 K |
| A. | μn = μp |
| B. | μn > μp |
| C. | μn < μp |
| D. | μn may be more or less than μp |
| Answer» C. Œºn < Œºp | |
| 500. |
The carriers of n channel JFET are |
| A. | free electrons and holes |
| B. | holes |
| C. | free electrons or holes |
| D. | free electrons |
| Answer» E. | |