831 + Interview Questions in SEMICONDUCTORS IN GENERAL AWARENESS Page 9 InterviewSolution

401.	The symbol represents :- A. NOT gateB. OR gateC. AND gateD. NOR gate
Answer» Correct Answer - A

Discussion

402.	The following circuit represents:A. OR gateB. XOR gateC. AND gateD. NAND gate
Answer» Correct Answer - B

Discussion

403.	Which of the following will have an output of 1 :- A. aB. cC. bD. d
Answer» Correct Answer - B

Discussion

404.	In a `p-n` junction–A. new holes and conduction electrons are produced continuously throughout the materialB. new holes and conduction electrons are produced continiously throughout the material except in the depletion regionC. holes and conduction electrons recombine continuously throughout the materialD. holes and conduction electrons recombine continuosly throughout the material except in the depletion region.
Answer» Correct Answer - A::D

Discussion

405.	The combination of the gates shown will produce A. OR gateB. AND gateC. NOR gateD. NAND gate
Answer» Correct Answer - B

Discussion

406.	The combination of the gates shown will produce A. OR gateB. AND gateC. NOR gateD. NAND
Answer» Correct Answer - C

Discussion

407.	The width of the forbidden band will be small inA. metalsB. insulatorsC. semiconductorsD. good conductors
Answer» Correct Answer - C

Discussion

408.	Pick the correct statement the reverse current in p-n junction diodeA. can be maximum and constantB. remains constant even after the breakdown voltageC. becomes infinity at breakdownD. reverse current is controlled by external resistance.
Answer» Correct Answer - A::C::D

Discussion

409.	At ordinary temperature, an increase in temperature, increases the conductivity ofA. a semiconductorB. a conductorC. a super conductorD. an insulator
Answer» Correct Answer - A

Discussion

410.	Wires `P` and `Q` have the same resistance at ordinary (room) temperature. When heated, resistance of `P` increases and that of `Q` decreases. We conclude thatA. P and Q are conductors of different materialsB. P is n-type semiconductor and Q is p-type semiconductorC. P is semiconductor and Q is conductorD. P is conductor and Q is semiconductor
Answer» Correct Answer - D

Discussion

411.	Which of the following statements is correct-A. Resistance of semiconductor decreases with increase in temperatureB. In an electric field, displacement of holes is opposite to the displacement of electronsC. Resistance of a conductor decreases with the increase in temperatureD. n-type semiconductor are neutral.
Answer» Correct Answer - A::B::D

Discussion

412.	Which of the following statements is correct-A. Resistance of extrinsic semiconductors can be changed as requiredB. in n-type semiconductor the umber of electrons increases in valence bandC. In p-type semiconductors the number of holes increases in valence bandD. In pure semiconductor fermi band is situated in between the valence band and conduction band
Answer» Correct Answer - A::C::D

Discussion

413.	The output of `OR` gate is `1`A. if both inputs are zeroB. if either or both inputs are 1C. only if both input are 1D. if either input is zero
Answer» Correct Answer - B

Discussion

414.	Give the logic symbol of NAND gate.A. an OR gateB. a NOT gateC. an AND gateD. a NAND gate
Answer» Correct Answer - B

Discussion

415.	Give the logic symbol of NOR gate.A. an OR gateB. A NOR gateC. A NAND gateD. an AND gate
Answer» Correct Answer - B

Discussion

416.	What is a forward current in case of zero biased p-n junction diode?
Answer» When the diode terminals are shorted together, some holes (majority carriers) in the p-side have enough thermal energy to overcome the potential barrier. Such carriers cross the barrier potential and contribute to current. This current is known as the forward current.

Discussion

417.	What is knee voltage?
Answer» In forward bias mode, the voltage for which the current in a p-n junction diode rises sharply is called knee voltage.

Discussion

418.	State some important features of the depletion region.
Answer» 1. It is formed by diffusion of electrons from n-region to the p-region. This leaves positively charged ions in the n-region. 2. The p-region accumulates electrons (negative charges) and the n-region accumulates the holes (positive charges). 3. The accumulation of charges on either sides of the junction results in forming a potential barrier and prevents flow of charges. 4. There are no charges in this region. 5. The depletion region has higher potential on the n-side and lower potential on the p-side of the junction.

418.

State some important features of the depletion region.

Answer»

1. It is formed by diffusion of electrons from n-region to the p-region. This leaves positively charged ions in the n-region.

2. The p-region accumulates electrons (negative charges) and the n-region accumulates the holes (positive charges).

3. The accumulation of charges on either sides of the junction results in forming a potential barrier and prevents flow of charges.

4. There are no charges in this region.

5. The depletion region has higher potential on the n-side and lower potential on the p-side of the junction.

Discussion

419.	Avalanche breakdown is due toA. shift of fermi levelB. curmulative effect of conductor band electron collisionC. widening of forbidden gapD. Low impurity concentration
Answer» Correct Answer - B

Discussion

420.	Symbolic representation of four logic gates are shown as A. (iii), (ii) and (i)B. (iii), (ii) and (v)C. (ii), (iv) and (iii)D. (ii), (iii) and (iv)
Answer» Correct Answer - C The symbols given in problem represent (i) OR gate (ii) AND gate (iii) NOT gate and (iv) NAND gate

Discussion

421.	What is the forbidden energy gap (in joule) for a Germanium crystal ?A. `1.6xx10^(-19) `JB. `1.12xx10^(-19) `JC. `3.2xx10^(-19) `JD. `2.24xx10^(-19) `J
Answer» Correct Answer - B `E_g=0.7 eV = 0.7xx1.6xx10^(-19) J = 1.12xx10^(-19) J`

Discussion

422.	The band of maximum energy in which electrons are present is called theA. conduction bandB. valence bandC. forbidden bandD. none of these
Answer» Correct Answer - B

Discussion

423.	In a triode, `gm=2xx10^(-3)ohm^(-1) , mu=42`, resistance load, R = 50 kilo ohm. The voltage amplification obtained from this triode will beA. 30.42B. 29.57C. 28.18D. 27.15
Answer» Correct Answer - B As, `A_(v)=(muR)/(r_(p)+R)=(muR)/((mu//g_(m))+R)` `=(42xx(50xx10^(3)))/(42//(2xx10^(-3))+50xx10^(3))=29.57`

Discussion

424.	When npn transistor is used as an ampliflerA. electrons move from base to collectorB. holes move from emitter to baseC. electrons move from collector to baseD. holes move from base to emitter
Answer» Correct Answer - D

Discussion

425.	The energy band gap is maximum inA. metalsB. superconductorsC. insulatorsD. semiconductors
Answer» Correct Answer - C

Discussion

426.	At absolute zero , Si acts asA. non-metalB. metalC. insulatorD. none of these
Answer» Correct Answer - C

Discussion

427.	Truth table for system of four `NAND` gates as shown in figure is : .A. `{:(A,B,Y),(0,0,1),(0,1,0),(1,0,0),(1,1,1):}`B. `{:(A,B,Y),(0,0,0),(0,1,1),(1,0,1),(1,1,0):}`C. `{:(A,B,Y),(0,0,0),(0,1,0),(1,0,1),(1,1,1):}`D. `{:(A,B,Y),(0,0,1),(0,1,1),(1,0,0),(1,1,0):}`
Answer» Correct Answer - B

Discussion

428.	If the Output of two NAND gates is given to input of a NAND gate. Then the truth table will be ofA. NOR gateB. OR gateC. AND gateD. XOR gate
Answer» Correct Answer - B

Discussion

429.	The relationship between `alpha` and `beta` is given byA. `alpha=b`B. `alpha=(1)/(beta)`C. `beta=(alpha)/(1-alpha)`D. `beta=(alpha)/(1+alpha)`
Answer» Correct Answer - C

Discussion

430.	In n-p-n transistor the emitter current will be equal toA. collector currentB. base currentC. sum of the collector and base currentD. difference of collector and base current
Answer» Correct Answer - C

Discussion

431.	In a p-n-p transistor, the n-type crystal works as aA. gateB. baseC. collectorD. emitter
Answer» Correct Answer - B

Discussion

432.	The current gain of a transistor is defined asA. the ratio of change in collector current to be change in emitter current for a constant value of collector voltage in a common base arrangementB. The ratio of charge in collector current to the change in base current for constant collector voltage in a common emitter arrangementC. the ratio of change in collector current to the change in base current for constant collector voltage in a common for constant arrangementD. The ratio of change in emitter current to the change in collector current for a constant emitter voltage in a common emitter arrangement
Answer» Correct Answer - A

Discussion

433.	In n-p-n transistor, the p-type crystal acts asA. base onlyB. collector onlyC. emitter onlyD. all of these
Answer» Correct Answer - A

Discussion

434.	Transistors may not replace vacuum tubes in all uses becauseA. transistors require longer warm-ups than vaccum tubesB. vacuum tubes are more resistance to shock and vibration tubes transistorsC. vacuum tubes can handle greater power than transistorsD. transistors use high voltage
Answer» Correct Answer - C

Discussion

435.	Three amplifier circuit are connected in series. The voltage gain of each is 5. What is the final voltage amplification?A. 15B. 125C. `5/3`D. 25
Answer» Correct Answer - B `A=A_1 xx A_2 xx A_3 ` = 125

Discussion

436.	The depletion layer in `P-N` junction region is caused byA. drift of holesB. drift of electronsC. diffusion of carriersD. migration a impurity ions
Answer» Correct Answer - C

Discussion

437.	Mark the correct statement(s)-A. Diode, LED and transistor are two leg devicesB. Diode, LED and resistor are two leg devicesC. Transistor and IC are 3 leg devicesD. IC and transistor are having same number of legs but not three
Answer» Correct Answer - B

Discussion

438.	Continuity test is made with multimeter by keeping the selector switch ON at-A. voltage positionB. current positionC. resistace positionD. None of these
Answer» Correct Answer - C

Discussion

439.	The frequency of oscillation in an oscillationA. `f=(1)/(sqrt(2pi LC)`B. `f=(1)/(2pi sqrt(LC))`C. `f=(sqrt(LC))/(2pi)`D. `f=(1)/(R)sqrt((L)/(C))`
Answer» Correct Answer - B

Discussion

440.	For sustained oscillation the product of gain of amplifier (A) and feedback factor (`beta`) isA. equal to 1B. less than 1C. greater than 1D. cannot be predicted
Answer» Correct Answer - A

Discussion

441.	In an oscillator when the signal from the output circuit is applied to input of the circuit then it calledA. feedbackB. ripple factorC. form factorD. refractive index
Answer» Correct Answer - A

Discussion

442.	Tank circuit of oscillator consists ofA. L and C in parallelB. RC in seriesC. L and C in seriesD. RC in parallel
Answer» Correct Answer - A

Discussion

443.	Which of the following is the part of oscillator ?A. Tank circuitB. AmplifierC. Feedback circuitD. All of these
Answer» Correct Answer - D

Discussion

444.	An electronic device that generates oscillations of desired frequency isA. oscillatorB. transformerC. voltage regulatorD. rectifier
Answer» Correct Answer - A

Discussion

445.	An electronic device which converts ac into dc is calledA. amplifierB. rectifierC. oscillatorD. induction coil
Answer» Correct Answer - B

Discussion

446.	The number of bonds formed in p-type and n-type semiconductors are respectively (A) 4,5 (B) 3,4 (C) 4,3 (D) 5,4
Answer» Correct option is: (B) 3,4

Discussion

447.	If the forward voltage in a semiconductor diode is chaged form 0.5 V to 2 V, then the forward current changed by 1.5 mA. The forward resistance of diode will be-A. 50 `Omega`B. 100 `Omega`C. 150 `Omega`D. 200 `Omega`
Answer» Correct Answer - D `R_f=(DeltaV)/(DeltaI)=0.3/(1.5xx10^(-3)) = 200 Omega`

Discussion

448.	If a `p-n` junction diode, a square input signal of `10 V` is applied as shown. Then the out put signal across `R_(L)` will be .A. B. C. D.
Answer» Correct Answer - A

Discussion

449.	If a `p-n` junction diode, a square input signal of `10 V` is applied as shown. Then the out put signal across `R_(L)` will be .A. B. C. D.
Answer» Correct Answer - D

Discussion

450.	The input characteristics of a transistor in CE mode is the graph obtained by plottingA. `I_(B)` against `I_(C)` at constant `V_(CE)`B. `I_(B)` against `V_(BE)` at constant `V_(CE)`C. `I_(B)` against `I_(C)` at constant `V_(BE)`D. `I_(B)` against `V_(CE)` at constant `V_(BE)`
Answer» Correct Answer - B The input characteristics of a transistor is a graph between `I_(B)` and `B_(BE)` at constant `V_(CE)`.

Discussion

Explore topic-wise InterviewSolutions in .

The symbol represents :- A. NOT gateB. OR gateC. AND gateD. NOR gate

The following circuit represents:A. OR gateB. XOR gateC. AND gateD. NAND gate

Which of the following will have an output of 1 :- A. aB. cC. bD. d

The combination of the gates shown will produce A. OR gateB. AND gateC. NOR gateD. NAND gate

The combination of the gates shown will produce A. OR gateB. AND gateC. NOR gateD. NAND

The width of the forbidden band will be small inA. metalsB. insulatorsC. semiconductorsD. good conductors

Pick the correct statement the reverse current in p-n junction diodeA. can be maximum and constantB. remains constant even after the breakdown voltageC. becomes infinity at breakdownD. reverse current is controlled by external resistance.

At ordinary temperature, an increase in temperature, increases the conductivity ofA. a semiconductorB. a conductorC. a super conductorD. an insulator

The output of `OR` gate is `1`A. if both inputs are zeroB. if either or both inputs are 1C. only if both input are 1D. if either input is zero

Give the logic symbol of NAND gate.A. an OR gateB. a NOT gateC. an AND gateD. a NAND gate

Give the logic symbol of NOR gate.A. an OR gateB. A NOR gateC. A NAND gateD. an AND gate

What is a forward current in case of zero biased p-n junction diode?

What is knee voltage?

State some important features of the depletion region.

Avalanche breakdown is due toA. shift of fermi levelB. curmulative effect of conductor band electron collisionC. widening of forbidden gapD. Low impurity concentration

Symbolic representation of four logic gates are shown as A. (iii), (ii) and (i)B. (iii), (ii) and (v)C. (ii), (iv) and (iii)D. (ii), (iii) and (iv)

What is the forbidden energy gap (in joule) for a Germanium crystal ?A. `1.6xx10^(-19) `JB. `1.12xx10^(-19) `JC. `3.2xx10^(-19) `JD. `2.24xx10^(-19) `J

The band of maximum energy in which electrons are present is called theA. conduction bandB. valence bandC. forbidden bandD. none of these

In a triode, `gm=2xx10^(-3)ohm^(-1) , mu=42`, resistance load, R = 50 kilo ohm. The voltage amplification obtained from this triode will beA. 30.42B. 29.57C. 28.18D. 27.15

When npn transistor is used as an ampliflerA. electrons move from base to collectorB. holes move from emitter to baseC. electrons move from collector to baseD. holes move from base to emitter

The energy band gap is maximum inA. metalsB. superconductorsC. insulatorsD. semiconductors

At absolute zero , Si acts asA. non-metalB. metalC. insulatorD. none of these

Truth table for system of four `NAND` gates as shown in figure is : .A. `{:(A,B,Y),(0,0,1),(0,1,0),(1,0,0),(1,1,1):}`B. `{:(A,B,Y),(0,0,0),(0,1,1),(1,0,1),(1,1,0):}`C. `{:(A,B,Y),(0,0,0),(0,1,0),(1,0,1),(1,1,1):}`D. `{:(A,B,Y),(0,0,1),(0,1,1),(1,0,0),(1,1,0):}`

If the Output of two NAND gates is given to input of a NAND gate. Then the truth table will be ofA. NOR gateB. OR gateC. AND gateD. XOR gate

The relationship between `alpha` and `beta` is given byA. `alpha=b`B. `alpha=(1)/(beta)`C. `beta=(alpha)/(1-alpha)`D. `beta=(alpha)/(1+alpha)`

In n-p-n transistor the emitter current will be equal toA. collector currentB. base currentC. sum of the collector and base currentD. difference of collector and base current

In a p-n-p transistor, the n-type crystal works as aA. gateB. baseC. collectorD. emitter

In n-p-n transistor, the p-type crystal acts asA. base onlyB. collector onlyC. emitter onlyD. all of these

Transistors may not replace vacuum tubes in all uses becauseA. transistors require longer warm-ups than vaccum tubesB. vacuum tubes are more resistance to shock and vibration tubes transistorsC. vacuum tubes can handle greater power than transistorsD. transistors use high voltage

Three amplifier circuit are connected in series. The voltage gain of each is 5. What is the final voltage amplification?A. 15B. 125C. `5/3`D. 25

The depletion layer in `P-N` junction region is caused byA. drift of holesB. drift of electronsC. diffusion of carriersD. migration a impurity ions

Mark the correct statement(s)-A. Diode, LED and transistor are two leg devicesB. Diode, LED and resistor are two leg devicesC. Transistor and IC are 3 leg devicesD. IC and transistor are having same number of legs but not three

Continuity test is made with multimeter by keeping the selector switch ON at-A. voltage positionB. current positionC. resistace positionD. None of these

The frequency of oscillation in an oscillationA. `f=(1)/(sqrt(2pi LC)`B. `f=(1)/(2pi sqrt(LC))`C. `f=(sqrt(LC))/(2pi)`D. `f=(1)/(R)sqrt((L)/(C))`

For sustained oscillation the product of gain of amplifier (A) and feedback factor (`beta`) isA. equal to 1B. less than 1C. greater than 1D. cannot be predicted

In an oscillator when the signal from the output circuit is applied to input of the circuit then it calledA. feedbackB. ripple factorC. form factorD. refractive index

Tank circuit of oscillator consists ofA. L and C in parallelB. RC in seriesC. L and C in seriesD. RC in parallel

Which of the following is the part of oscillator ?A. Tank circuitB. AmplifierC. Feedback circuitD. All of these

An electronic device that generates oscillations of desired frequency isA. oscillatorB. transformerC. voltage regulatorD. rectifier

An electronic device which converts ac into dc is calledA. amplifierB. rectifierC. oscillatorD. induction coil

The number of bonds formed in p-type and n-type semiconductors are respectively (A) 4,5 (B) 3,4 (C) 4,3 (D) 5,4

If the forward voltage in a semiconductor diode is chaged form 0.5 V to 2 V, then the forward current changed by 1.5 mA. The forward resistance of diode will be-A. 50 `Omega`B. 100 `Omega`C. 150 `Omega`D. 200 `Omega`

If a `p-n` junction diode, a square input signal of `10 V` is applied as shown. Then the out put signal across `R_(L)` will be .A. B. C. D.

If a `p-n` junction diode, a square input signal of `10 V` is applied as shown. Then the out put signal across `R_(L)` will be .A. B. C. D.

The input characteristics of a transistor in CE mode is the graph obtained by plottingA. `I_(B)` against `I_(C)` at constant `V_(CE)`B. `I_(B)` against `V_(BE)` at constant `V_(CE)`C. `I_(B)` against `I_(C)` at constant `V_(BE)`D. `I_(B)` against `V_(CE)` at constant `V_(BE)`