831 + Interview Questions in SEMICONDUCTORS IN GENERAL AWARENESS Page 17 InterviewSolution

801.	The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in theA. crystal structureB. change in the number of charge careerC. type of bondingD. none of these
Answer» Correct Answer - B

Discussion

802.	The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in theA. crystal structureB. variation of the number of charge carriers with temperatureC. type of bondingD. variation of scattering mechanism with temperature
Answer» Correct Answer - B The difference in the variation of resistance with temperature in metal and semiconductor is caused due to difference in the variation of the number of charge carriers with temperature.

Discussion

803.	The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in theA. crystal structureB. variation of the number of charge carries with temperatureC. type of bondingD. variation of scattering mechanism with temperature
Answer» Correct Answer - B

Discussion

804.	The part of a transistor which is most heavily doped to produce large number of majority carriers isA. emitterB. baseC. collectorD. can be any of the above three
Answer» Correct Answer - B

Discussion

805.	State the reason, why GaAs is most commonly used in making of a solar cell.A. a zener diodeB. a light emitting diodeC. a transistorD. a half wave rectifier
Answer» Correct Answer - B

Discussion

806.	GaAs (with a band gap =`1.5eV`) as an LED can emitA. blue lightB. infrared raysC. ultraviolet raysD. `X`-rays
Answer» Correct Answer - B `lambda=(1242)/(1.5)=828nm`, infrared rays

Discussion

807.	The logic circuit shown below has the input waveforms ‘A’ and ‘B’ as shown. Pick out the correct output waveform A. B. C. D.
Answer» Correct Answer - D `Y=(bar(bar(A)+bar(B))) =A.B` It is AND gate

Discussion

808.	The Fig shown input waveforms A and B to a logic gate. Draw the output waveform for an OR gate. Write the truth table for this logic gate and draw its logic symbol. A. B. C. D.
Answer» Correct Answer - D If lattice constant of semiconductor is decreased, then `E_(C)` and `E_(V)` decrease but `E_(g)` increase.

Discussion

809.	What is the number of junctions in a semiconductor diode ?A. OneB. TwoC. ThreeD. infinite
Answer» Correct Answer - A

Discussion

810.	In its crystalline structure, every Si or Ge atoms are attached to other atoms byA. coordinate bondB. electrovalent bondC. covalent bondD. hydrogen bond
Answer» Correct Answer - C Si and Ge have four valence electrons. In its crystalline structure, every Si or Ge atom tends to share one of its four valence electrons with each of its four nearest neighbour atoms and also to take share of one electron from each such neighbour. These shared electron pairs are referred to as forming a covalent bond or simply a valence band.

Discussion

811.	In pure semiconductor, the number of conduction electrons is `6 xx 10^18` per cubic metre. How many holes are there in a sample of size 1 cm x 1 cm x 1 mm?A. `6xx10^19`B. `6xx10^15`C. `6xx10^12`D. `6xx10^10`
Answer» Correct Answer - C In a pure semiconductor, no. of electrons = no. of holes Volume of the semiconductor =`10^(-2)xx10^(-2)xx10^(-3)` `=10^(-7) m^3` ``therefore` No. of holes = `10^(-7)xx6xx10^19=6xx10^12`

Discussion

812.	Semiconductor Ge has forbidden gap of 1.43 eV. Calculate maximum wavelength which result from electron hole combination.
Answer» Correct Answer - 8654 Å Energy `E_(min)=(hc)/(lamda_(max))` `becauselamda_(max)=(hc)/(E_(min))` `=(6.6xx10^(-34)xx3xx10^(8))/(1.43xx1.6xx10^(-19))m` `=8.654xx10^(-7)m` `=8654xx10^(-10)m` `=8654Å`

Discussion

813.	Let `n_(p) and n_(e)` be the number of holes and conduction electrons respectively in a semiconductor. Then,A. `n_(p) gt N_(e)` in an intrinsic semiconductor, `I lt I_(p)+I_(e)`B. `n_(p)=n_(e)` in an extrinsic semiconductor, `I gt I_(p) +I_(e)`C. `n_(p) =n_(e)` in an intrinsic semiconductor, `I=I_(p)+I_(e)`D. `n_(p) gt n_(e)` in an intrinsic semiconductor, `I=0`
Answer» Correct Answer - C In intrinsic semiconductors, the number of free electron, `n_(e)` is equal to the number of holes, `n_(h)`. That is `n_(e)=n_(h)=n_(i)`, where `n_(i)` is called intrinsic carrier concentration, `I=I_(p)+I_(e)`.

Discussion

814.	At elevated temperature, few of covalent bonds of Si or Ge are broken a vacancy in the bond is created. Effective charge of vacancy or hole isA. positiveB. negativeC. neutralD. sometimes positive and sometimes negative
Answer» Correct Answer - A In semiconductor, as the temperature increases, more thermal energy becomes available to electrons and some of these electrons may break-away (becoming free electrons contributing to conduction). The thermal energy effectively ionises only a few atoms in the crystalline lattice and creates a vacancy in the bond. These holes behave as positive charge carriers.

Discussion

815.	In an ammeter, 10% of the main current is passing through galvanometer, if the galvanometer is shunted with a 10 `Omega` resistance. What is the resistance of the galvanometer ?A. almost same of the previous valueB. double of the previous valueC. half of the previousD. exactly same of the previous value
Answer» Correct Answer - C

Discussion

816.	What would you do to obtain a large deflection of the galvanometer?A. the shunt resistance shuold be increasedB. the shunt resistance should be decreaseC. should check the connectionsD. should change the keys used by him
Answer» Correct Answer - B

Discussion

817.	The value of `bar1 + bar1` isA. 2B. 0C. 1D. 10
Answer» Correct Answer - B

Discussion

818.	Barrier potential of a `p-n` junction diode does not depend onA. TemperatureB. Diode designC. Forward and reverse biasingD. Doping density
Answer» Correct Answer - B It does not depend upon the diode design.

Discussion

819.	A plane e.m. wave travelling along the x-direction has a wavelength of 3mm. The variation in the electric field occurs in the y-direction with an amplitude `66Vm^-1`. The equation for the electric and magnetic fields as a function of x and t are respectivelyA. `E_(y)=33cospixx10^(11)(t-(x)/(c)),B_(z)=1.1xx10^(-7)cospixx10^(11)(t-(x)/(c))`B. `E_(y)=11cos2pixx10^(11)(t-(x)/(c)),B_(y)=11xx10^(-7)cos2pixx10^(11)(t-(x)/(c))`C. `E_(x)=33cospixx10^(11)(t-(x)/(c)),B_(x)=11xx10^(-7)cospixx10^(11)(t-(x)/(c))`D. `E_(y)=66cos2pixx10^(11)(t-(x)/(c)),B_(z)=2.2xx10^(-7)cos2pixx10^(11)(t-(x)/(c))`
Answer» Correct Answer - D

Discussion

820.	For given CE biasing circuit, if voltage across collector-emitter is `12 V` and current gain is 100 and base current is 0.04 mA then determine the value of collector resistance `R_(C)`. .
Answer» `because V_(CE)=V_(C C)-I_(C) xx R_(C)` `because R_(c)=(V_(C C)-V_(CE))/(beta I_(B))=(20-12)/(100 xx 0.04 xx 10^(-3))=2 k Omega`.

Discussion

821.	A digital signal-A. is less reliable than analog signalB. is more reliable than analog signalC. is equally reliable as the analog signalD. none of the above.
Answer» Correct Answer - B

Discussion

822.	Audio signal cannot be transmitted becauseA. can be sent directly over the air for large distanceB. cannot be sent directly over the air for large distanceC. possess very high frequencyD. none of the above
Answer» Correct Answer - B

Discussion

823.	The power in a two-wire transmission line travels :-A. Inside the conductorsB. Outside the conductorsC. None of the aboveD. Both inside and outside the conductors
Answer» Correct Answer - B

Discussion

824.	The sound waves after being converted into electrical waves are not transmitted as such because-A. They travel with the speed of soundB. The frequency is not constantC. They are heavily absorbed by the atmosphereD. The height of antenna has to be increased several times
Answer» Correct Answer - D

Discussion

825.	Assertion: The television broadcasting becomes weaker with increasing distance. Reason: The power transmitted from T.V. transmitter varies inversely as the distance of the receiver.A. Statetment-I is True, Statement-II is True , Statement-II is a correct explanation for Statement-IB. Statement-I is True, Statement-II is True , Statement-II is NOT a correct explanation for Statement-IC. Statement-I is True, Statement-II is FalseD. Statement-I is False, Statement-II is True
Answer» Correct Answer - C

Discussion

826.	For television broadcasting, the frequency employed is normallyA. 30 -300 M HzB. 30-300 G HzC. 30-300 K HzD. 30-300 Hz
Answer» Correct Answer - A

Discussion

827.	Assertion: The surface wave propagation is used for medium wave band and for television broadcasting. Reason: The surface waves travel directly from transmitting antenna to receiver antenna through atmosphere.A. Statetment-I is True, Statement-II is True , Statement-II is a correct explanation for Statement-IB. Statement-I is True, Statement-II is True , Statement-II is NOT a correct explanation for Statement-IC. Statement-I is True, Statement-II is FalseD. Statement-I is False, Statement-II is True
Answer» Correct Answer - D

Discussion

828.	The frequencies of electromagnetic waves employed in space communication lie in the range of -A. `10^(4)Hz` to `10^(7)Hz`B. `10^(4)Hz` to `10^(11)Hz`C. 1 Hz to `10^(4)Hz`D. 1 Hz to `10^(11)Hz`
Answer» Correct Answer - B

Discussion

829.	a p -n juction (D) shown in the figure can act an a rectifier An alternatting current source (V) is connected in the circuit The corrent (I ) in the resistor® can be shown by :A. B. C. D.
Answer» Correct Answer - C

Discussion

830.	a p -n juction (D) shown in the figure can act an a rectifier An alternatting current source (V) is connected in the circuit The corrent (I ) in the resistor® can be shown by :A. B. C. D.
Answer» Correct Answer - B

Discussion

831.	For the given circult shown in fig to act as full wave rectifer , the ac input should be connected across …… and ……. And the d. c output would supplied across …….. And ………. A. A,C and B,DB. B,D and A,CC. A,B and C,DD. C,A and D,B
Answer» Correct Answer - B

Discussion

Explore topic-wise InterviewSolutions in .

The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in theA. crystal structureB. change in the number of charge careerC. type of bondingD. none of these

The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in theA. crystal structureB. variation of the number of charge carriers with temperatureC. type of bondingD. variation of scattering mechanism with temperature

The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in theA. crystal structureB. variation of the number of charge carries with temperatureC. type of bondingD. variation of scattering mechanism with temperature

The part of a transistor which is most heavily doped to produce large number of majority carriers isA. emitterB. baseC. collectorD. can be any of the above three

State the reason, why GaAs is most commonly used in making of a solar cell.A. a zener diodeB. a light emitting diodeC. a transistorD. a half wave rectifier

GaAs (with a band gap =`1.5eV`) as an LED can emitA. blue lightB. infrared raysC. ultraviolet raysD. `X`-rays

The logic circuit shown below has the input waveforms ‘A’ and ‘B’ as shown. Pick out the correct output waveform A. B. C. D.

The Fig shown input waveforms A and B to a logic gate. Draw the output waveform for an OR gate. Write the truth table for this logic gate and draw its logic symbol. A. B. C. D.

What is the number of junctions in a semiconductor diode ?A. OneB. TwoC. ThreeD. infinite

In its crystalline structure, every Si or Ge atoms are attached to other atoms byA. coordinate bondB. electrovalent bondC. covalent bondD. hydrogen bond

In pure semiconductor, the number of conduction electrons is `6 xx 10^18` per cubic metre. How many holes are there in a sample of size 1 cm x 1 cm x 1 mm?A. `6xx10^19`B. `6xx10^15`C. `6xx10^12`D. `6xx10^10`

Semiconductor Ge has forbidden gap of 1.43 eV. Calculate maximum wavelength which result from electron hole combination.

At elevated temperature, few of covalent bonds of Si or Ge are broken a vacancy in the bond is created. Effective charge of vacancy or hole isA. positiveB. negativeC. neutralD. sometimes positive and sometimes negative

What would you do to obtain a large deflection of the galvanometer?A. the shunt resistance shuold be increasedB. the shunt resistance should be decreaseC. should check the connectionsD. should change the keys used by him

The value of `bar1 + bar1` isA. 2B. 0C. 1D. 10

Barrier potential of a `p-n` junction diode does not depend onA. TemperatureB. Diode designC. Forward and reverse biasingD. Doping density

For given CE biasing circuit, if voltage across collector-emitter is `12 V` and current gain is 100 and base current is 0.04 mA then determine the value of collector resistance `R_(C)`. .

A digital signal-A. is less reliable than analog signalB. is more reliable than analog signalC. is equally reliable as the analog signalD. none of the above.

Audio signal cannot be transmitted becauseA. can be sent directly over the air for large distanceB. cannot be sent directly over the air for large distanceC. possess very high frequencyD. none of the above

The power in a two-wire transmission line travels :-A. Inside the conductorsB. Outside the conductorsC. None of the aboveD. Both inside and outside the conductors

The sound waves after being converted into electrical waves are not transmitted as such because-A. They travel with the speed of soundB. The frequency is not constantC. They are heavily absorbed by the atmosphereD. The height of antenna has to be increased several times

For television broadcasting, the frequency employed is normallyA. 30 -300 M HzB. 30-300 G HzC. 30-300 K HzD. 30-300 Hz

The frequencies of electromagnetic waves employed in space communication lie in the range of -A. `10^(4)Hz` to `10^(7)Hz`B. `10^(4)Hz` to `10^(11)Hz`C. 1 Hz to `10^(4)Hz`D. 1 Hz to `10^(11)Hz`

a p -n juction (D) shown in the figure can act an a rectifier An alternatting current source (V) is connected in the circuit The corrent (I ) in the resistor® can be shown by :A. B. C. D.

a p -n juction (D) shown in the figure can act an a rectifier An alternatting current source (V) is connected in the circuit The corrent (I ) in the resistor® can be shown by :A. B. C. D.

For the given circult shown in fig to act as full wave rectifer , the ac input should be connected across …… and ……. And the d. c output would supplied across …….. And ………. A. A,C and B,DB. B,D and A,CC. A,B and C,DD. C,A and D,B