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Electronic Device Physics Quiz | objective questions | Physics General Knowledge Questions | MCQ | Electronic device and communication

1 >>basic materials used in the present solid state electronic devices like diode, transistor, ICs, etc are ?
  • (A) metals
  • (B) insulators
  • (C) semiconductors
  • (D) conductors
2 >>In the case of metals the valence and conduction bands have ?
  • (A) no overlap, energy gap is small
  • (B) no overlap, energy gap =0
  • (C) no overlap, energy gap is large
  • (D) overlap, energy gap =0
3 >>In the case of semiconductors the valence and conduction bands have ?
  • (A) overlap, energy gap =0
  • (B) no overlap, energy gap =0
  • (C) no overlap, energy gap is large
  • (D) no overlap, energy gap is small
4 >>Hole is a vacancy or lack of an electron and can travel through the material. It can ?
  • (A) None of these
  • (B) move only if an electron stops
  • (C) serves as an additional current carrier
  • (D) only serves as a vacant spot and cannot conduct current
5 >>In a pure, or intrinsic, semiconductor, valence band holes and conduction-band electrons are always present ?
  • (A) in equal numbers
  • (B) None of these
  • (C) such that number of electrons is greater than the number of holes
  • (D) such that number of holes is greater than the number of electrons








6 >>doping of semiconductor is the process of ?
  • (A) removing impurity elements
  • (B) adding a surface coating
  • (C) None of these
  • (D) adding of impurity elements
7 >>Motion of hole is a convenient way of describing ?
  • (A) the actual motion of conduction electrons
  • (B) the actual motion of energy gap
  • (C) the actual motion of free electrons
  • (D) the actual motion of bound electrons
8 >>The total current in a semiconductor is ?
  • (A) hole current only
  • (B) the sum of electron and hole currents
  • (C) the difference of electron and hole currents
  • (D) electron current only
9 >>In n-type semiconductor the fifth electron ?
  • (A) is not capable of moving
  • (B) is not present
  • (C) needs high energy to be set free
  • (D) needs low energy to be set free
10 >>In n-type semiconductor the total number of conduction electrons ne is due to the, ?
  • (A) holes contributed by donors and those generated intrinsically
  • (B) electrons contributed by donors and those generated intrinsically
  • (C) electrons generated intrinsically only
  • (D) holes generated intrinsically only
11 >>in n-type semiconductor majority carriers and minority carriers are respectively ?
  • (A) germanium and silicon
  • (B) aluminium and boron
  • (C) electrons and holes
  • (D) holes and electrons
12 >>in p-type semiconductor the dopant is ?
  • (A) always germanium
  • (B) always silicon
  • (C) acceptor
  • (D) donor





.13 >>in p-type semiconductor ?
  • (A) nhe
  • (B) nh>>ne
  • (C) nh>ne
  • (D) nh=ne

14 >>The electron and hole concentration in a semiconductor in thermal equilibrium is given by ?
  • (A) nenh=2n2i
  • (B) 2nenh=n2i
  • (C) nenh=n2i
  • (D) nenh=2n3i
15 >>Diffusion in a p-n junction is due to ?
  • (A) concentration gradient
  • (B) carrier injection
  • (C) None of these
  • (D) minority carriers
16 >>Depletion region (space charge) is formed because ?
  • (A) majority carriers while diffusing to the other side leave behind immobile ionized atoms
  • (B) majority carriers while diffusing to the other side leave behind highly mobile ionized atoms
  • (C) majority carriers while drifting to the other side leave behind immobile ionized atoms
  • (D) minority carriers while diffusing to the other side leave behind immobile ionized atoms
17 >>In a p-n junction, as the diffusion process continues the width of the depletion zone ?
  • (A) remain same
  • (B) decrease
  • (C) oscillate
  • (D) decrease
18 >>Which of the following is not a semiconductor? ?
  • (A) Si
  • (B) Ge
  • (C) As
  • (D) All of these
19 >>In a semiconductor, the forbidden energy gap between the valance band and the conduction band is of the order of ?
  • (A) 15ev
  • (B) 5ev
  • (C) 1 Mev
  • (D) Mev








20 >>The main difference between conductors, semiconductors and insulators is because of ?
  • (A) Work function
  • (B) Width of forbidden energy gap
  • (C) energy of electrons
  • (D) Mobility of electrons


21 >>In an insulator, the forbidden energy gap between the valance band and conduction band is of the order of ?
  • (A) 1 ev
  • (B) 5 ev
  • (C) 10-3 ev
  • (D) 2 Mev
22 >>When the conductivity of a semiconductor is only due to breaking of the covalent bonds, the semiconductor is called ?
  • (A) extrinsic
  • (B) donor
  • (C) intrinsic
  • (D) acceptor
23 >>A small impurity is added to germanium to get p-type semiconductor. This impurity is a ?
  • (A) Bivalent substance
  • (B) Monovalent substance
  • (C) Trivalent substance
  • (D) Pentavalent substance
24 >>To obtain a p-type germanium semiconductor, it must be doped with ?
  • (A) An
  • (B) In
  • (C) As
  • (D) P
25 >>The impurity atoms with which pure silicon should be doped to make a p-type semiconductor are those of ?
  • (A) Bi
  • (B) B
  • (C) An
  • (D) P





26 >>When arsenic is added as an impurity to silicon, the resulting material is ?
  • (A) p-type semiconductor
  • (B) n-type semiconductor
  • (C) n-type conductor
  • (D) none of these
27 >>When Ge crystal is doped with phosphorus atoms, it becomes ?
  • (A) superconductor
  • (B) insulators
  • (C) p type
  • (D) n type
28 >>The depletion layer in the p-n junction region is caused by ?
  • (A) Drift of electrons
  • (B) Diffusion of carriers
  • (C) Migration of impurity ions
  • (D) Drift of holes
29 >>The potential barrier in the depletion layer is due to ?
  • (A) ions
  • (B) holes
  • (C) electrons
  • (D) forbidden gap
30 >>A p-n junction has a thickness of the order of ?
  • (A) 1 mm
  • (B) 10-12 cm
  • (C) 1 cm
  • (D) 10-6cm
31 >>The conductivity of P – type semiconductor is due to ?
  • (A) none of the above.
  • (B) both electron and holes
  • (C) electrons
  • (D) holes
32 >>An N-type Ge is obtained on doping the Ge- crystal with ?
  • (A) B
  • (B) gold
  • (C) p type
  • (D) Al
33 >>A P – type crystal is obtained by doping A) silicon with arsenic, B) silicon with aluminium, C) Ge with boron, D) Ge with phosphorus, Hence, say whether ?
  • (A) (A and C) are correct
  • (B) (B and D) are correct
  • (C) (B and C) are correct
  • (D) (A and D) are correct
34 >>Majority current carriers in N – types are ?
  • (A) positive ions
  • (B) electrons
  • (C) negative ions
  • (D) holes
35 >>A solid having uppermost energy – band partially filled with electrons is called ?
  • (A) a semi – conductor
  • (B) none of the above
  • (C) a conductor
  • (D) an insulator
36 >>The number of valence electrons in a good conductor is generally ?
  • (A) 5
  • (B) 4
  • (C) 3 or less than 3
  • (D) 6 or more than 6
37 >>Electrons are forbidden in a band (in a crystal) called the ?
  • (A) conduction band
  • (B) forbidden band
  • (C) one of the above
  • (D) valance band
38 >>The behavior of Ge as a semi – conductor is due to the width of ?
  • (A) conduction band being small and narrow
  • (B) forbidden band being small and narrow
  • (C) conduction band being large
  • (D) forbidden band being large
39 >>P-N junction can be used as ?
  • (A) modulator
  • (B) rectifier
  • (C) amplifier
  • (D) oscillator
40 >>To provide the abundance of holes the impurity added should be ?
  • (A) tetravalent
  • (B) pentavalent
  • (C) monovalent
  • (D) trivalent


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