The Higher Institute of Engineering at Al-Shorouk

City
Department of Electrical Power and Machine
The Higher Institute of Engineering
Engineering Academic Year: 2022/2023 Semester: First
El-Shorouk City
Course Code: ECE 231 Level: 2nd year Electrical Power and Machine
Engineering Dept.
Course Name: Electronics and Logic Circuits
Sheet 1
Q1. Choose the correct answer:
1. …….. the smallest particle of an element that possesses the unique characteristics of that element.
a. Atom b. Nucleus c. Proton d. Electron
2. The amount of energy required to produce full conduction across the pn junction in forward bias.
a. Barrier potential b. Energy gap c. Ionization d. Doping
3. A material that easily conducts electrical current.
a. Insulator b. Conductor c. Semiconductor d. None of the
mentioned
4. A solid material in which the atoms are arranged in a symmetrical pattern.
a. Atom b. Crystal c. Proton d. Doping
5. The process of imparting impurities to an intrinsic semiconductive material in order to control its
conduction characteristics.
a. Crystal b. Atom c. Doping d. Ionization
6. The basic particle of negative electrical charge.
a. Proton b. Nucleus c. Electron d. Atom
7. An electron that has acquired enough energy to break away from the valence band of the parent atom;
also called a …….
a. conduction b. free electron c. a, and b d. None of the
electron mentioned
8. The absence of an electron in the valence band of an atom.
a. conduction b. free electron c. a, and b d. hole
electron
9. A material that does not normally conduct current.
a. Conductor b. Semiconductor c. a, or b d. Insulator
10. The removal or addition of an electron from or to a neutral atom so that the resulting atom has a net
positive or negative charge.
a. Ionization b. Crystal c. Recombination d. Electron hole pair
11. The boundary between two different types of semiconductive materials.
a. pn junction b. doping c. atom d. crystal
12. The basic particle of positive charge.
a. Electron b. Proton c. Atom d. Nucleus
13. A material that lies between conductors and insulators in its conductive properties. Silicon, germanium,
and carbon are examples.
a. Conductors b. Semiconductors c. Insulator d. None of the
mentioned
14. Every known element has….
a. the same type of b. the same number c. a unique type of d. several different
atoms of atoms atom types of atoms
15. An atom consists of…...
a. one nucleus and b. one nucleus and c. protons, electrons, d. b, and c
only one electron one or more and neutrons
electrons
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16. The nucleus of an atom is made up of….
a. protons and b. electrons and c. electrons d. electrons and
neutrons protons neutrons
17. Valence electrons are…..
a. in the closest orbit b. in the most distant c. in various orbits d. not associated with
to the nucleus orbit from the around the a particular atom
nucleus nucleus
18. A positive ion is formed when…..
a. a valence electron b. there are more c. two atoms bond d. an atom gains an
breaks away from holes than together extra valence
the atom electrons in the electron
outer orbit
19. The most widely used semiconductive material in electronic devices is ….
a. Germanium b. Carbon c. Copper d. Silicon
20. The difference between an insulator and a semiconductor is ….
a. a wider energy gap b. the number of free c. the atomic d. all of the
between the electrons structure mentioned
valence band and
the conduction
band
21. The atomic number of silicon is ….
a. 8 b. 14 c. 4 d. 32
22. The atomic number of germanium is
a. 8 b. 14 c. 4 d. 32
23. The most widely used semi-conductive material in electronic device is …
a. silicon b. carbon c. Germanium d. copper
24. The energy band in which free electrons exist is the
a. first band b. conduction band c. second band d. valence band
25. Electron-holes pairs are produced by
a. ionization b. thermal energy c. Recombination d. doping
26. Recombination is when
a. a crystal is formed b. a positive and a c. an electron falls d. a valence electron
negative ion bond into a hole becomes a
together conduction
electron
27. Each atom in a silicon crystal has
a. no valence b. eight valence c. four valence d. four conduction
electrons because electrons because electrons electrons
all are shared with all are with other
others atoms atoms
28. The current in a semiconductor is produced by
a. holes only b. electrons only c. both electrons d. negative ions
and holes
29. In an intrinsic semiconductor
b. the free electrons c. there are only d. there are as many
a. there are no free are thermally holes electrons as there
electrons produced are holes
30. A pure semiconductor behaves like an insulator at 0o K because
a. There is no b. Drift velocity of c. Free electrons are d. Energy possessed
recombination of free electrons is not available for by electrons at
very small that low
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 electrons with current temperature is
holes conduction almost zero
31. In semiconductor the forbidden energy gap lies
a. Just below the b. Just above the c. Either above or d. Between the
conduction band conduction band below the valence band and
conduction band conduction band
32. A semiconductor is formed by ……… bonds.
a. Covalent b. Electrovalent c. Co-ordinate d. None of the above
33. The process of adding an impurity to an intrinsic semiconductor is called
a. atomic b. doping c. Recombination d. ionization
modification
34. A trivalent impurity is added to silicon to create
a. germanium b. an n-type c. a depletion region d. a p-type
semiconductor semiconductor
35. When diode is forward-biased
a. the only current is b. the only current is c. the current is d. the only current is
hole current produced by produced by both electron current
majority carriers holes and
electrons
36. The purpose of a pentavalent impurity is to
a. increase the b. create minority c. reduce the d. increase the
number of free carriers conductivity of number of holes
electrons silicon
37. Holes in an n-type semiconductor are
a. minority carriers b. majority carriers c. minority carriers d. majority carriers
that are thermally that are thermally that are produced that are produced
produced produced by doping by doping
38. A pn junction is formed by
a. ionization b. the boundary of a c. the recombination d. the collision of a
p-type and an n- of electrons and proton and a
type material holes neutron
39. The depletion region is consist of
a. nothing but b. positive and c. no majority d. b, and c
minority carriers negative ions carriers
40. In a PN junction with no external voltage, the electric field between acceptor and donor ions is called
a. Peak b. Barrier c. Threshold d. Path
41. For a pn junction diode, the current in reverse bias may be
a. Few miliamperes b. Between 0.2 A and c. Few amperes d. Few micro or nano
15 A amperes
42. In a PN junction when the applied voltage overcomes the ........ potential, the diode current is large,
which is known as .............
a. Depletion, b. Reverse, reverse c. Resistance, d. Barrier, forward
negative bias bias reverse bias bias
43. The term bias means
a. a dc voltage is b. the ratio of c. neither a, b nor c d. the amount of
applied to control majority carriers current across a
the operation of a to minority diode
device carriers
44. In a reverse biased pn junction, the current through the junction increases abruptly at
a. 0.5 V b. 1.1 V c. 0.72 V d. Breakdown
voltage

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45. Although current is blocked in reverse bias
a. there is some b. there is very small c. there is an d. None of the
current due to current due to avalanche current mentioned
majority carriers minority carriers
46. When a voltmeter is placed across a forward-biased diode, it will read a voltage approximately equal to
a. the diode barrier b. the bias battery c. the total circuit d. 0 V
potential voltage voltage
47. At room temperature N-type material will have....
a. More of electrons b. More of holes c. Equal number of d. None of the
electrons and mentioned
holes
48. A forward biased pn junction diode has a resistance of the order of
a. Ω b. k Ω c. M Ω d. None of the
mentioned
49. A reverse biased pn junction has resistance of the order of
a. Ω b. k Ω c. M Ω d. None of the
mentioned
50. Each element in the periodic table has a ….. atomic structure
a. Different b. Unique c. a, and b d. none of the
mentioned
51. The quantum model is considered a ….. accurate representation than Bohr model.
a. More b. Less c. The same d. None of the
mentioned
52. The Bohr model of the atom is that electrons can circle around the nucleus only in specific orbits, which
correspond to discrete energy levels called
a. Shells b. Conduction c. Free d. None of the
mentioned
53. The atomic number is the number of …… in the nucleus.
a. Electrons b. Protons c. Neutrons d. a, and b
54. The outermost occupied shell is called the ….. shell
a. Conduction b. Valence c. Free d. First
55. A given atom has a …… number of shells
a. Fixed b. Variable c. a, and b d. a, or b
56. Electrons near the nucleus have …. energy than those in more distant orbits
a. Less b. More c. Equal d. None of the
mentioned
57. The maximum number of electrons (𝑵𝒆 ) that can exist in each shell of an atom is a fact of nature and
can be calculated by the formula
a. 𝑵𝒆 = 𝒏𝟐 b. 𝑵𝒆 = 𝟐𝒏𝟐 c. 𝑵𝒆 = 𝟐𝒏𝟑 d. 𝑵𝒆 = 𝟐𝒏𝟒
58. Electrons that are in orbits farther from the nucleus have …. energy and are less tightly bound to the
atom than those closer to the nucleus
a. higher b. lower c. the same d. None of the
mentioned
59. Electrons with the …. energy exist in the outermost shell of an atom and are relatively loosely bound
to the atom
a. Highest b. Lowest c. Equally d. None of the
mentioned
60. If a valence electron acquires a sufficient amount of energy, called …. energy, it can actually escape
from the outer shell and the atom’s influence
a. Ionization b. Recombination c. Electron hole d. None of the
pair mentioned
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61. The departure of a valence electron leaves a neutral atom with an excess of ….. charge.
a. Negative b. Positive c. a, and b d. a, or b
62. The process of losing a valence electron is known as….. , and the resulting positively charged atom is
called a …. ion.
a. Ionization, b. Ionization, c. Ionization, d. None of the
positive negative neutral mentioned
63. An …… is a material that does not conduct electrical current under normal conditions
a. Conductor b. Insulator c. Semiconductor d. a, or b
64. Valence electrons are tightly bound to the atoms; therefore, there are very …. free electrons in an
insulator
a. Few b. Large c. a, and b d. a, or b
65. A ….. is a material that easily conducts electrical current.
a. Conductor b. Insulator c. Semiconductor d. None of the
mentioned
66. The single-element semiconductors are characterized by atoms with …. valence electrons
a. Four b. Five c. Eight d. None of the
mentioned
67. The difference in energy between the valence band and the conduction band is called an ….
a. energy gap b. band gap c. a, and b d. None of the
mentioned
68. The core includes everything except the ……
a. Valence b. Free electrons c. Protons d. None of the
electrons mentioned
69. Silicon has …… number of electrons in the valence shell with respect to the germanium
a. The same b. Different c. a, and b d. None of the
mentioned
70. Silicon is ….. stable than germanium at high temperatures.
a. More b. Less c. The same d. None of the
mentioned
71. An intrinsic crystal is one that has …. impurities
a. Different b. No c. a, and b d. None of the
mentioned
72. When an electron jumps to the conduction band, a vacancy is left in the valence band within the crystal.
This is know as…..
a. Hole b. Free electron c. Valence d. Recombination
electron
73. For every electron raised to the conduction band by external energy, there is one hole left in the valence
band. This is known as…..
a. Recombination b. Electron hole c. Doping d. Recombination
pair
74. …… occurs when a conduction-band electron loses energy and falls back into a hole in the valence band
a. Recombination b. Electron hole c. Doping d. None of the
pair mentioned
75. Within the crystalline structure, there are ….. types of charge movement (current).
a. Two b. Three c. One d. None of the
mentioned
76. Since semiconductors are generally poor conductors, their conductivity can be increased by the
controlled addition of impurities to the intrinsic (pure) semiconductive material. This is known as:
a. Recombination b. Electron hole c. Doping d. None of the
pair mentioned
77. The process of increasing the number of current carriers (electrons or holes) is known as:
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 a. Doping b. Recombination c. Electron hole d. None of the
pair mentioned
78. The electrons are called the ….. carriers in n-type material
a. Majority b. Minority c. a, or b d. None of the
mentioned
79. The Holes in an n-type material are called …… carriers
a. Majority b. Minority c. a, or b d. None of the
mentioned
80. To increase the number of conduction-band electrons in intrinsic silicon, pentavalent impurity atoms
are added. This is corresponding to ……. semiconductor
a. n type b. p type c. a, and b d. None of the
mentioned
81. To increase the number of holes in intrinsic silicon, trivalent impurity atoms are added. This is
corresponding to …… semiconductor.
a. n type b. p type c. a, and b d. None of the
mentioned
82. The electrons are called the minority carriers in ….. material
a. n type b. p type c. a, and b d. None of the
mentioned
83. The Holes in an ….. material are called majority carriers
a. n type b. p type c. a, and b d. None of the
mentioned
84. The pn junction can be constructed via ……
a. n type b. p type c. a, and b d. a, or b
85. When the pn junction is formed, the n region loses …… as they diffuse across the junction.
a. free electrons b. holes c. a, or b d. None of the
mentioned
Best Regards,
Dr. Khaled Ramadan

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