Questions · Page 7 of 9

M.C.Q (1 Marks)

MCQ 3011 Mark
To a germanium sample, traces of gallium are added as an impurity. The resultant sample would behave like
  • A
    A conductor
  • A P-type semiconductor
  • C
    An N-type semiconductor
  • D
    An insulator
Answer
Correct option: B.
A P-type semiconductor
 A P-type semiconductor
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MCQ 3021 Mark
When phosphorus and antimony are mixed in zermaniun, then
  • A
    P-type semiconductor is formed
  • N-type semiconductor is formed
  • C
    Both (a) and (b)
  • D
    None of these
Answer
Correct option: B.
N-type semiconductor is formed
N-type semiconductor is formed
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MCQ 3031 Mark
The process of adding impurities to the pure semiconductor is called
  • A
     Drouping
  • B
     Drooping
  •  Doping
  • D
    None of these
Answer
Correct option: C.
 Doping
Doping
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MCQ 3041 Mark
The energy band gap is maximum in
  • A
    Metals
  • B
    Superconductors
  • Insulators
  • D
    Semiconductors
Answer
Correct option: C.
Insulators
Insulators
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MCQ 3051 Mark
In a semiconductor
  • A
    There are no free electrons at any temperature
  • B
     The number of free electrons is more than that in a conductor
  •  There are no free electrons at 0 K
  • D
    None of these
Answer
Correct option: C.
 There are no free electrons at 0 K
There are no free electrons at 0 K
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MCQ 3061 Mark
Which impurity is doped in Si to form N-type semi-conductor?
  • A
    Al
  • B
    B
  •  As
  • D
    None of these
Answer
Correct option: C.
 As
As
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MCQ 3071 Mark
The valence band and conduction band of a solid overlap at low temperature, the solid may be
  •  A metal
  • B
     A semiconductor
  • C
    An insulator
  • D
     None of these
Answer
Correct option: A.
 A metal
 A metal
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MCQ 3081 Mark
In intrinsic semiconductor at room temperature, number of electrons and holes are
  • A
     Unequal
  • Equal
  • C
    Infinite
  • D
     Zero
Answer
Correct option: B.
Equal
Equal
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MCQ 3091 Mark
Electric current is due to drift of electrons in
  • A
    Metallic conductors
  • B
    Semi-conductors
  • Both (a) and (b)
  • D
    None of these
Answer
Correct option: C.
Both (a) and (b)
Both (a) and (b)
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MCQ 3101 Mark
Resistivity of a semiconductor depends on
  • A
     Shape of semiconductor
  •  Atomic nature of semiconductor
  • C
     Length of semiconductor
  • D
     Shape and atomic nature of semiconductor
Answer
Correct option: B.
 Atomic nature of semiconductor
Atomic nature of semiconductor
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MCQ 3111 Mark
In extrinsic semiconductors
  • A
    The conduction band and valence band overlap
  • B
    The gap between conduction band and valence band is more than 16 eV
  • The gap between conduction band and valence band is near about 1 eV
  • D
    The gap between conduction band and valence band will be 100 eV and more
Answer
Correct option: C.
The gap between conduction band and valence band is near about 1 eV
The gap between conduction band and valence band is near about 1 eV
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MCQ 3121 Mark
If $n_e$ and $v_d$ be the number of electrons and drift velocity in a semiconductor. When the temperature is increased
  • $n_e$ increases and $v_d$ decreases
  • B
    $ {n}_ {e} $ decreases and $v_{\mathrm{d}}$ increases
  • C
    Both $\mathrm{n}_{\mathrm{e}}$ and $\mathrm{v}_{\mathrm{d}}$ increases
  • D
    Both $n_e$ and $v_d$ decreases
Answer
Correct option: A.
$n_e$ increases and $v_d$ decreases
$n_e$ increases and $v_d$ decreases
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MCQ 3131 Mark
Intrinsic semiconductor is electrically neutral. Extrinsic semiconductor having large number of current carriers would be
  • A
    Positively charged
  • B
    Negatively charged
  • C
    Positively charged or negatively charged depending upon the type of impurity that has been added
  • Electrically neutral
Answer
Correct option: D.
Electrically neutral
Electrically neutral
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MCQ 3141 Mark
A piece of semiconductor is connected in series in an electric circuit. On increasing the temperature, the current in the circuit will
  • A
    Decrease
  • B
     Remain unchanged
  •  Increase
  • D
    Stop flowing
Answer
Correct option: C.
 Increase
 Increase
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MCQ 3151 Mark
In a P-type semi-conductor, germanium is dopped with
  • A
    Gallium
  • B
    Boron
  • C
    Aluminium
  • All of these
Answer
Correct option: D.
All of these
All of these
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MCQ 3161 Mark
Choose the correct statement
  • A
    When we heat a semiconductor its resistance increases
  • When we heat a semiconductor its resistance decreases
  • C
    When we cool a semiconductor to 0 K then it becomes super conductor
  • D
    Resistance of a semiconductor is independent of temperature
Answer
Correct option: B.
When we heat a semiconductor its resistance decreases
 When we heat a semiconductor its resistance decrease
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MCQ 3171 Mark
Which of the following statements is true for an N-type semi-conductor
  • The donor level lies closely below the bottom of the conduction band
  • B
    The donor level lies closely above the top of the valence band
  • C
    The donor level lies at the halfway mark of the forbidden energy gap
  • D
    None of above
Answer
Correct option: A.
The donor level lies closely below the bottom of the conduction band
The donor level lies closely below the bottom of the conduction band
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MCQ 3181 Mark
In semiconductors at a room temperature
  • The valence band is partially empty and the conduction band is partially filled
  • B
    The valence band is completely filled and the conduction band is partially filled
  • C
    The valence band is completely filled
  • D
    The conduction band is completely empty
Answer
Correct option: A.
The valence band is partially empty and the conduction band is partially filled
The valence band is partially empty and the conduction band is partially filled
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MCQ 3191 Mark
Which of the following has negative temperature coefficient of resistance
  • A
    Copper
  • B
    Aluminium
  • C
    Iron
  • Germanium
Answer
Correct option: D.
Germanium
Germanium
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MCQ 3201 Mark
When germanium is doped with phosphorus, the doped material has
  • A
    Excess positive charge
  • B
    Excess negative charge
  • More negative current carriers
  • D
    More positive current carriers
Answer
Correct option: C.
More negative current carriers
More negative current carriers
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MCQ 3211 Mark
The charge on a hole is equal to the charge of
  • A
     Zero
  •  Proton
  • C
    Neutron
  • D
    Electron
Answer
Correct option: B.
 Proton
Proton
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MCQ 3221 Mark
The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the
  • A
    Variation of scattering mechanism with temperature
  • B
    Crystal structure
  • Variation of the number of charge carriers with temperature
  • D
    Type of bon
Answer
Correct option: C.
Variation of the number of charge carriers with temperature
Variation of the number of charge carriers with temperature
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MCQ 3231 Mark
Donor type impurity is found in
  • A
     Trivalent elements
  • Pentavalent elements
  • C
    In both the above
  • D
    None of these
Answer
Correct option: B.
Pentavalent elements
 Pentavalent elements
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MCQ 3251 Mark
If $n _{ e }$ and $n _{ h }$ are the number of electrons and holes in a semiconductor heavily doped with phosphorus, then
  •  $n_e \gg n_h$
  • B
    $n_e \ll n_h$
  • C
    $n _{ e } \leq n _{ h }$
  • D
     $n _{ e }= n _{ h }$
Answer
Correct option: A.
 $n_e \gg n_h$
 $n_e \gg n_h$
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MCQ 3261 Mark
At room temperature, a P-type semiconductor has
  • Large number of holes and few electrons
  • B
    Large number of free electrons and few holes
  • C
    Equal number of free electrons and holes
  • D
    No electrons or holes
Answer
Correct option: A.
Large number of holes and few electrons
Large number of holes and few electrons
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MCQ 3271 Mark
GaAs is
  • A
    Element semiconductor
  • Alloy semiconductor
  • C
    Bad conductor
  • D
    Metallic semiconductor
Answer
Correct option: B.
Alloy semiconductor
Alloy semiconductor
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MCQ 3281 Mark
Semiconductor is damaged by the strong current due to
  • A
    Lack of free electron
  • Excess of electrons
  • C
    Excess of proton
  • D
    None of these
Answer
Correct option: B.
Excess of electrons
Excess of electrons
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MCQ 3291 Mark
In N-type semiconductors, majority charge carriers are
  • A
    Holes
  • B
    Protons
  • C
    Neutrons
  • Electrons
Answer
Correct option: D.
Electrons
 Electrons
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MCQ 3301 Mark
In a P-type semiconductor, germanium is doped with
  • A
    Boron
  • B
    Gallium
  • C
    Aluminium
  • All of these
Answer
Correct option: D.
All of these
All of these
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MCQ 3311 Mark
When the temperature of silicon sample is increased from 27℃ to 100℃, the conductivity of silicon will be
  • Increased
  • B
    Decreased
  • C
    Remain same
  • D
    Zero
Answer
Correct option: A.
Increased
 Increased
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MCQ 3321 Mark
At ordinary temperatures, the electrical conductivity of semi conductors in mho/meter is in the range
  • A
     $10^{-3}$ to $10^{-4}$
  • $10^6$ to
  • C
    $10^{-6}$ to
  • D
    $10^{-10}$ to $10^{-16}$
Answer
Correct option: B.
$10^6$ to
$10^6$ to $10^9$
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MCQ 3341 Mark
The band gap in Germanium and silicon in eV respectively is
  • 0.7, 1.1
  • B
    1.1, 0.7
  • C
    1.1, 0
  • D
    0, 1.1
Answer
Correct option: A.
0.7, 1.1
0.7, 1.1
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MCQ 3351 Mark
Which is the correct relation for forbidden energy gap in conductor, semi conductor and insulator
  • A
    $\Delta Eg _{ c }>\Delta Eg _{ sc }>\Delta Eg _{\text {insulator }}$
  • $\Delta Eg _{\text {insulator }}>\Delta Eg _{ sc }>\Delta Eg _{\text {conductor }}$
  • C
     $\Delta Eg _{\text {conductor }}>\Delta Eg _{\text {insulator }}>\Delta Eg _{\text {sc }}$
  • D
    $\Delta Eg _{ sc }>\Delta Eg _{\text {conductor }}>\Delta Eg _{\text {insulator }}$
Answer
Correct option: B.
$\Delta Eg _{\text {insulator }}>\Delta Eg _{ sc }>\Delta Eg _{\text {conductor }}$
 $\Delta Eg _{\text {insulator }}>\Delta Eg _{ sc }>\Delta Eg _{\text {conductor }}$
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MCQ 3361 Mark
A pure semiconductor behaves slightly as a conductor at
  • Room temperature
  • B
    Low temperature
  • C
    High temperature
  • D
    Both (b) and (c)
Answer
Correct option: A.
Room temperature
Room temperature
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MCQ 3371 Mark
For germanium crystal, the forbidden energy gap in joules is
  • $1.12 \times 10^{-19}$
  • B
    $1.76 \times 10^{-19}$
  • C
    $1.6 \times 10^{-19}$
  • D
    Zero
Answer
Correct option: A.
$1.12 \times 10^{-19}$
(a) $1.12 \times 10^{-19}$
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MCQ 3381 Mark
To obtain electrons as majority charge carriers in a semiconductor, the impurity mixed is
  • A
    Monovalent
  • B
    Divalent
  • C
    Trivalent
  • Pentavalent
Answer
Correct option: D.
Pentavalent
Pentavalent
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MCQ 3391 Mark
The state of the energy gained by valance electrons when the temperature is raised or when electric field is applied is called as
  • A
    Valance band
  • Conduction band
  • C
    Forbidden band
  • D
    None of these
Answer
Correct option: B.
Conduction band
 Conduction band
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MCQ 3401 Mark
N-type semiconductors will be obtained, when germanium is doped with
  • A
    Phosphorus
  • B
    Aluminium
  • C
     Arsenic
  • Both (a) or (c)
Answer
Correct option: D.
Both (a) or (c)
 Both (a) or (c)
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MCQ 3411 Mark
An N-type and P-type silicon can be obtained by doping pure silicon with
  • A
    Arsenic and Phosphorous
  • B
    Indium and Aluminium
  • Phosphorous and Indium
  • D
    Aluminium and Boron
Answer
Correct option: C.
Phosphorous and Indium
 Phosphorous and Indium
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MCQ 3421 Mark
Resistance of semiconductor at 0 K is
  • A
    Zero
  • Infinite
  • C
    Large
  • D
    Small
Answer
Correct option: B.
Infinite
 Infinite
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MCQ 3431 Mark
The addition of antimony atoms to a sample of intrinsic germanium transforms it to a material which is
  • A
    Superconductor
  • B
    An insulator
  • N-type semiconductor
  • D
    P-type semiconductor
Answer
Correct option: C.
N-type semiconductor
 N-type semiconductor
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MCQ 3441 Mark
The intrinsic semiconductor becomes an insulator at
  • A
    0℃
  • B
    --100℃
  • C
    300 K
  • 0 K
Answer
Correct option: D.
0 K
 0 K
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MCQ 3451 Mark
In a semiconductor the separation between conduction band and valence band is of the order of
  • A
    100 eV
  • B
    10 eV
  • 1eV
  • D
    0 eV
Answer
Correct option: C.
1eV
1eV
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MCQ 3461 Mark
Fermi level of energy of an intrinsic semiconductor lies
  • In the middle of forbidden gap
  • B
    Below the middle of forbidden gap
  • C
    Above the middle of forbidden gap
  • D
    Outside the forbidden gap
Answer
Correct option: A.
In the middle of forbidden gap
In the middle of forbidden gap
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MCQ 3471 Mark
(USS 133) Indium impurity in germanium makes
  • A
    N-type
  • P-type
  • C
    Insulator
  • D
    Intrinsic
Answer
Correct option: B.
P-type
P-type
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MCQ 3481 Mark
In intrinsic semiconductor at room temperature, number of electrons and holes are
  • Equal
  • B
    Zero
  • C
    Unequal
  • D
     Infinite
Answer
Correct option: A.
Equal
Equal
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MCQ 3491 Mark
If $N _{ p }$ and $N _{ e }$ be the numbers of holes and conduction electrons in an extrinsic semiconductor, then
  • A
    $N _{ P }> N _e$
  • B
    $N _{ p }= N _{ e }$
  • C
    $N _{ P }< N _{ e }$
  • $N _{ p }> N _{ e }$ or $N _{ p }< N _{ e }$ depending on the nature of impurity
Answer
Correct option: D.
$N _{ p }> N _{ e }$ or $N _{ p }< N _{ e }$ depending on the nature of impurity
(d) $N _{ p }> N _{ e }$ or $N _{ p }< N _{ e }$ depending on the nature of impurity
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MCQ 3501 Mark
A semiconductor is cooled from  $T _1 K$ to $T _2 K$. Its resistance
  • A
     Will decrease
  • Will increase
  • C
    Will first decrease and then increase
  • D
     Will not change
Answer
Correct option: B.
Will increase
 Will increase
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