JEE Questions for Physics Semiconductor Devices Quiz 7 - MCQExams.com

With the fall of temperature, the forbidden energy gap of a semiconductor
  • Increases
  • decreases
  • remains unchanged
  • sometime increases and sometimes decreases
In a semiconductor, the forbidden energy gap between the valence band and the conduction band is of the order is
  • 1 MeV
  • 0.1 MeV
  • 1 eV
  • 5 eV
The ratio of electron and hole current in a semiconductor is 7/4 and the ratio of drift velocities of electrons and holes is 5/4, then ratio of concentrations of electrons and holes will be
  • 5/7
  • 7/5
  • 25/49
  • 49/25
Three semiconductors are arranged in the increasing order of their energy gap as follows. The correct arrangement is
  • tellurium, germanium, silicon
  • tellurium, silicon, germanium
  • silicon, germanium, tellurium
  • Silicon, tellurium, germanium
The Fermi level of an intrinsic semiconductor is pinned at the centre of the band gap. The probability of occupation of the highest electron state in valence band at room temperature, will be
  • Zero
  • Between zero and half
  • Half
  • One
In the half wave rectifier circuit operating from 50 hz mains frequency, the fundamental frequency in the ripple would be
  • 25 hz
  • 50 hz
  • 70.7 hz
  • 100 hz
Which filter circuit is better?
  • π type
  • Choke input type
  • Capacitor type
  • None of the above
Two identical p-n junctions may be connected in series with a battery in three ways as shown in the adjoining figure. The potential drop across the p-n junctions are equal in
Physics-Semiconductor Devices-87648.png
  • circuit 1 and circuit 2
  • circuit 2 and circuit 3
  • circuit 3 and circuit 1
  • circuit 1 only
In bridge rectifier circuit, Fig., the input signal should be connected between
Physics-Semiconductor Devices-87649.png
  • A and D
  • B and C
  • A and C
  • B and D
P-N junction is
  • ohmic resistance
  • non-ohmic resistance
  • negative resistance
  • positive resistance
The r.m.s value of output current in full wave rectifier is
  • I0/π
  • I0/2
  • I0/√2
  • 2I0
For a junction diode, when Io is the reverse saturation current then the forward current If is given by

  • Physics-Semiconductor Devices-87650.png
  • 2)
    Physics-Semiconductor Devices-87651.png

  • Physics-Semiconductor Devices-87652.png

  • Physics-Semiconductor Devices-87653.png
The equivalent resistance of the circuit (Fig), across AB is given by
Physics-Semiconductor Devices-87655.png
  • 6.2Ω
  • 5.64Ω
  • 8.2Ω
  • 5.6Ω or 8.2 Ω
The bond that exists in a semiconductor is
  • covalent bond
  • ionic bond
  • metallic bond
  • hydrogen bond
In a triclinic crystal system
  • a ≠ b ≠ c, α ≠ β ≠ γ
  • a = b = c, α ≠ β ≠ γ
  • a ≠ b ≠ c, α ≠ β = γ
  • a = b ≠ c, α = β = γ
The current amplification factor α of a common base transistor and the current amplification factor β of a common emitter transistor are NOT related by

  • Physics-Semiconductor Devices-87657.png
  • 2)
    Physics-Semiconductor Devices-87658.png

  • Physics-Semiconductor Devices-87659.png

  • Physics-Semiconductor Devices-87660.png
In p-type semiconductor
  • major current carrier is electrons
  • major carrier is mobile negative ions
  • major carrier is mobile holes
  • the number of mobile holes exceeds the number of acceptors
The p-type semiconductor the majority and minority charge carriers are respectively
  • protons and electrons
  • electrons and protons
  • electrons and holes
  • holes and electrons
The following configuration of gate is equivalent to (Fig.)
Physics-Semiconductor Devices-87662.png
  • NAND
  • XOR
  • OR
  • None of these
The forward bias diode is

  • Physics-Semiconductor Devices-87664.png
  • 2)
    Physics-Semiconductor Devices-87665.png

  • Physics-Semiconductor Devices-87666.png

  • Physics-Semiconductor Devices-87667.png
In the terminology related to semiconductor, what is a hole?
  • Space which is a negatively charged
  • Space which was previously occupied by an electron
  • A hole in a space time distribution of the universe
  • Dense area in a space which even absorb light i.e. black hole
Which one is forward biased?

  • Physics-Semiconductor Devices-87668.png
  • 2)
    Physics-Semiconductor Devices-87669.png

  • Physics-Semiconductor Devices-87670.png
  • None of these
The least doped region in a transistor is
  • emitter
  • collector
  • base
  • either emitter collector
  • either collector or base
If the forward bias voltage in a diode is increased the length of depletion region would
  • decrease
  • increase
  • no change
  • first increase and then decrease
In forward bias made, the P.N junction diode resistance will __________ .
  • Infinity
  • Zero
  • Less
  • More
To a germanium sample, traces of gallium are added as an impurity. The resultant sample would behave like
  • a conductor
  • a p-type semiconductor
  • an n-type semiconductor
  • an insulator
In a properly biased transistor
  • both deplection layers are equally large
  • both depletion layers are equally small
  • emitter-base depletion layer is large but base collector depletion layer is small
  • emitter-base depletion layer is small but base collector depletion layer is large
  • both depletion layers vanish
When npn transistor is used as an amplifier
  • electrons move from base to collector
  • holes move from emitter to base
  • electrons move from collector to base
  • holes move from base to emitter
Consider an n-p-n transistor amplifier in common emitter configuration. The current gain of the transistor is 100. If the collector current changes by 1 mA, what will be the change in emitter current?
  • 1.1 mA
  • 1.01 mA
  • 0.01 mA
  • 10 mA
C, Si and Ge have same no. of valence electrons. C is an insulator because energy required to take one electron out from
  • Si is more
  • C is more
  • Ge is more
  • C is less
Ionisation energy of isolated phosphorous atoms 10 eV. Ionisation energy of same atom in Si is nearly ____________ eV(Relative Permitivity of silicon = 12)
  • 0.1
  • 0.2
  • 0.3
  • 0.4
By adding _____________impurity in intrinsic semiconductor P type semiconductor is made. charge of these P type semiconductor is_________
  • Trivalent, neutral
  • Pentavalent, neutral
  • Pentavalent, positive
  • Trivalent, negative
Strong overlaping of different atomic orbitals makes
  • Different energy level
  • Energy band
  • Conductor
  • Insulators
We can not make p–n junction diode by making P type semi–condutor join with N – type semi–conductor, Because
  • Inter-atomic spacing becomes less than 1Å
  • P – type will repel N – type
  • There will be discontinuity for the flowing charge carriers
  • Semi-conducting properties will be lost
For p–n junction, which statement is incorrect
  • Donor atoms are depleted of their holes in junction
  • No net charge exists far from junction
  • Barrier potential VB is generate
  • Energy VB is to be surmounted before any charge can flow across junction
The intrinsic semi-conductor has :
  • A finite resistance which does not change with temperature
  • Infinite resistance which decreases with temperature
  • Finite resistance which decreases with temperature
  • Finite resistance which does not change with temperature
The behaviour of Ge as semi-conductor is due to width of :
  • Conduction band being large
  • Forbidden band being large
  • Conduction band being small
  • Forbidden band being small and narrow
Which of the following is not the advantage of PN junction diode over tube valve ?
  • Unlimited life
  • No warming-up time after switching
  • Large efficiency
  • Low consumption of Power
A current gain for a transistor working as CB amplifier is 0.90. If emitter current is 10 mA, then base current is __________ .
  • 1 mA
  • 2 mA
  • 0.1 mA
  • 0.2 mA

Physics-Semiconductor Devices-87674.png
  • 12
  • 6
  • 24
  • 48
At 0 K temp, a N - type semi-conductor :
  • Does not have any charge carriers
  • Has few holes but no free electrons
  • Few holes and few electrons
  • Has equal number of holes and electrons
In Si-crystal, impurity donor atom have valency.
  • 2
  • 3
  • 4
  • 5
A N-P-N transistor conducts when collector is ___________ and emitter is __________with respect to base.
  • Positive, negative
  • Positive, positive
  • Negative, negative
  • Negative, positive
A full wave rectifier is operating at 50Hz, 220V the fundamental frequency of ripple will be__________.
  • 50 Hz
  • 75 Hz
  • 110 Hz
  • 100 Hz
Reverse bias applied on a junction diode :
  • Raises the potential barrier
  • Increases majority charge carrier current
  • Lowers the potential barrier
  • Increases the temperature of junction
Digital circuits can be made to be respective use of :
  • AND gate
  • OR gate
  • NOT gate
  • NAND gate
The output current versus time curve of a rectifier is shown in the figure. The average value of the output-current is __________ .
Physics-Semiconductor Devices-87676.png
  • 0
  • 2)
    Physics-Semiconductor Devices-87677.png

  • Physics-Semiconductor Devices-87678.png

  • Physics-Semiconductor Devices-87679.png
For a transistor, in a common base configuration the alternating current gain α is given by :

  • Physics-Semiconductor Devices-87680.png
  • 2)
    Physics-Semiconductor Devices-87681.png

  • Physics-Semiconductor Devices-87682.png

  • Physics-Semiconductor Devices-87683.png

Physics-Semiconductor Devices-87684.png

  • Physics-Semiconductor Devices-87685.png
  • 2)
    Physics-Semiconductor Devices-87686.png

  • Physics-Semiconductor Devices-87687.png

  • Physics-Semiconductor Devices-87688.png
How many NAND gates are used to form AND gate ?
  • 1
  • 2
  • 3
  • 4
0:0:1


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