PRACTICE PROBLEM ELEX SEMICONDUCTOR
1. An electronic circuit that converts ac voltage into dc voltage
2. A diode circuit that clips off or removes part of a waveform above and/or below a specified level.A protective
device that burns open when the current exceeds a rated limit.
3. The voltage across the diode when it is forward-biased; Approximately the same as the barrier potential and
typically 0.7 V for silicon
4. A circuit that adds a dc level to an ac voltage using a diode and a capacitor.
5. A type of full-wave rectifier consisting of a center-tapped transformer and two diodes.
6. An energy band in which electrons orbit the nucleus of an atom.
7. A material that lies between conductors and insulators in its conductive properties. Silicon, germanium, and
carbon are examples.
8. The condition in which a pn junction prevents current.
9. The most numerous charge carrier in a doped semiconductor material (either free electrons or holes).
10. The boundary between two different types of semiconductor materials.
11. An atom with five valence electrons.
12. The path an electron takes as it circles around the nucleus of an atom.
13. An uncharged particle found in the nucleus of an atom
14. The least numerous charge carrier in a doped semiconductor material (either free electrons or holes).
15. The removal or addition of an electron from or to a neutral atom so that the resulting atom (called an ion) has a
net positive or negative charge.
16. The pure or natural state of a material.
17. A material that does not conduct current.
18. The absence of an electron in the valence band of an atom.
19. An electron that has acquired enough energy to break away from the valance band of the parent atom, also
called a conduction electron.
20. The condition in which a pn junction conducts current.
21. The conduction electron and the hole created when the electron leaves the valence band.
22. The process of imparting impurities to an intrinsic semiconductor material in order to control its conduction
characteristics.
23. The area near a pn junction on both sides that has no majority carriers.
24. The rate of flow of free electrons.
25. Clamper is also known as
26. The pattern or arrangement of atoms forming a solid material.
27. Also known as free electron.
28. The creation of free electrons through zener effect is also known as
29. The application of a dc voltage to a pn junction to make it either conduct or block current.
30. The amount of energy required to produce full conduction across the pn junction in forward bias.
31. Approximately the number of protons and neutrons in the nucleus of an atom.
32. The smallest particle of an element that possesses the unique characteristics of that element.
33. The p region of a diode.
34. A measure of effectiveness of a power supply filter in reducing the ripple voltage; ratio of the ripple voltage to
the dc output voltage.
35. The circuit that converts ac voltage into dc voltage.
36. A type of full-wave rectifier consisting of four diodes arranged in a 4-cornered configuration.
37. Related to the outer shell of an atom.
38. An atom with three valence electrons.
39. The basic particle of positive charge.
40. The basic particle of negative electrical charge.
41. The nonlinear internal resistance of a semiconductor material.
PRACTICE PROBLEM ELEX SEMICONDUCTOR
42. A graph showing the relationship of current versus voltage in a diode.
43. Related to the bonding of two or more atoms by the interaction of their valence electrons.
44. The central part of an atom, includes the nucleus and all but the valence electrons.
45. A material that conducts electrical current very well.
46. The n region of a diode.
47. The rapid buildup of conduction electrons due to excessive reverse-bias voltage.
48. The number of electrons in a neutral atom.
49. A circuit using diodes and capacitors that increases the input voltage by two, three, or four times.
50. The process and technique of identifying and locating faults in an electronic circuit or system.
51. The small variation in the dc output voltage of a filtered rectifier caused by the charging and discharging of the
filter capacitor.
52. An electronic device or circuit that maintains an essentially constant output voltage for a range of input voltage
or load values; one part of a power supply.
53. A capacitor or combination of capacitor and inductor used to reduce the variation of the output voltage from a
rectifier.
54. A diode modeling circuit which considers the threshold voltage, average resistance and switch as the diode’s
equivalent circuit.
55. What is the other name of Esaki diode?
56. Approximately, the atomic weight of germanium is
57. Each pair of positive and negative ions at the junction is called a/an
58. A semiconductor in its purest form is called
59. The process of a free (conduction band) electron falling into a hole in the valence band of an atom.
60. The central part of an atom containing protons and neutrons
61. What is the VRRM (PIV rating) for the 1N4001 rectifier diode?
62. The maximum number of electrons in each shell of an atom
63. There is a small amount of current across the barrier of a reverse-biased diode. This current is called
64. The process of emitting photons from a semiconductive material is called.
65. The normal operating region for a zener diode is the?
66. The reverse bias diode capacitance is termed as
67. Schottky diodes are also known as
68. The time taken by the diode to operate in the reversed condition from forward conduction.
69. Solid state devices were first manufactured during
MCQ
70. An 8.2 V zener has a resistance of 5 Ω. The actual voltage across its terminals when the current is 25 mA is
A) 8.2 V.
B) 125 mV.
C) 8.325 V.
D) 8.075 V.
71. A 6.2 V zener is rated at 1 watt. The maximum safe current the zener can carry is
A) 1.61 A.
B) 161 mA.
C) 16.1 mA.
D) 1.61 mA.
72. Refer to Figure 3-1. If VIN attempts to increase, VR will
A) increase.
B) decrease.
PRACTICE PROBLEM ELEX SEMICONDUCTOR
C) remain the same.
D) none of the above
73. Refer to Figure 3-1. If VIN increases, IZ will
A) increase.
B) decrease.
C) remain the same.
D) none of the above
74. Refer to Figure 3-1. If VIN decreases, IR will
A) increase.
B) decrease.
C) remain the same.
d) none of the above
75. An LED is forward-biased. The diode should be on, but no light is showing. A possible trouble might be
A) the diode is open.
B) the series resistor is too small.
C) none. The diode should be off if forward-biased.
D) the power supply voltage is too high.
76. Which of the following materials has the smallest leakage current?
A. Germanium
B. Carbon
C. Sulfur
D. Silicon
77. The Schottky diode is used
A) in high-power circuits.
B) in circuits requiring negative resistance.
C) in very fast-switching circuits.
D) in power supply rectifiers.
78. A tunnel diode is used
A) in high-power circuits.
B) in circuits requiring negative resistance.
C) in very fast-switching circuits.
D) in power supply rectifiers.
79. You have an application for a diode to be used in a tuning circuit. A type of diode to use might be
A) an LED.
B) a Schottky diode.
C) a Gunn diode.
D) a varactor
PRACTICE PROBLEM ELEX SEMICONDUCTOR
80. Zener diodes with breakdown voltages less than 5 V operate predominantly in what type of breakdown?
A) avalanche
B) zener
C) varactor
D) Schottky
81. When temperature increases, barrier potential _________.
A. Remains the same
B. Decreases
C. Increase
D. Either increases or decreases depending on the semiconductor material used
82. Zener diodes with breakdown voltages greater than 5 V operate predominantly in what type of breakdown?
A) avalanche
B) zener
C) varactor
D) Schottky
83. Avalanche effects occurs at
A. Higher reverse voltages
B. Lower reverse voltages
C. Higher forward voltages
D. Lower forward voltages
84. What type of diode is commonly used in electronic tuners in TVs?
A) varactor
B) Schottky
C) LED
D) Gunn
85. LEDs are made out of
A) silicon.
B) germanium.
C) gallium.
86. One of the important diode parameters which gives the magnitude of current the diode candle without burning.
A. Reverse saturation current
B. Reverse current
C. Forward current
D. Forward breakdown current
87. Zener effect only depends on the
A. High-speed minority carriers
B. High-speed majority carriers
C. Intensity of the electric field
D. Intensity of the magnetic field
88. What type of diode maintains a constant current?
A) LED
B) zener
C) current regulator
D) pin
E) none of the above
89. What orbit controls the electrical property of the atom?
A. Valence orbit
B. First orbit
PRACTICE PROBLEM ELEX SEMICONDUCTOR
C. Fourth orbit
D. M shell
90. What diode operates only with majority carriers?
A) laser
B) tunnel
C) Schottky
D) step-recovery
91. What kind of diode is formed by joining a doped semiconductor region with a metal?
A) laser
B) tunnel
C) pin
D) Schottky
92. The most important application of Schottky diodes is in
A. Digital computers
B. Power supplies
C. Amplifier circuits
D. Voltage regulators
93. Which diode employs graded doping?
A) zener
B) LED
C) tunnel
D) step-recovery
94. What diode is used in seven-segment displays?
A) zener
B) LED
C) laser
D) Schottky
95. Back-to-back varactor diodes are used for what reason?
A) over-voltage protection
B) a wider tuning range
C) to eliminate harmonic distortion
D) no reason; only zeners are used in a back-to-back configuration
96. A diode conducts when it is forward-biased, and the anode is connected to the __________ through a limiting
resistor.
A) positive supply
B) negative supply
C) cathode
D) anode
97. Doping of a semiconductor material mean
A) that a glue-type substance is added to hold the material together.
B) that impurities are added to increase the resistance of the material.
C) that impurities are added to decrease the resistance of the material.
D) that all impurities are removed to get pure silicon
98. A silicon diode is forward-biased. You measure the voltage to ground from the anode at _____, and the voltage
from the cathode to ground at _____.
A) 0 V, 0.3 V
B) 2.3 V, 1.6 V
PRACTICE PROBLEM ELEX SEMICONDUCTOR
C) 1.6 V, 2.3 V
D) 0.3 V, 0 V
99. Reverse breakdown is a condition in which a diode
A) is subjected to a large reverse voltage.
B) is reverse-biased and there is a small leakage current.
C) has no current flowing at all.
D) is heated up by large amounts of current in the forward direction
100.
As the forward current through a silicon diode increases, the voltage across the diode.
A) increases to a 0.7 V maximum.
B) decreases.
C) is relatively constant.
D) decreases and then increases
101.
Percentage ripple can be calculated by getting the _________ and multiplying the result by100%.
A. Ratio of the input resistance and input voltage
B. Product of the ac current to dc current
C. Ratio of the ac voltage to dc voltage
D. Addition of the ac and dc component of the given signal
102.
Which statement best describes an insulator?
A) A material with many free electrons.
B) A material doped to have some free electrons.
C) A material with few free electrons.
D) No description fits
103.
As a general rule, ________ are found only in semiconductors.
A. Electrons
B. Bulk resistances
C. Depletion layers
D. Holes
104.
When temperature of a pure semiconductor is increased, its resistance
A. Decreases
B. Remains the same
C. Increases
D. Cannot be estimated
105.
What occurs in pn diodes when the electric field in the depletion layer increases to the point where it
can break covalent bonds and generate electron hole pairs?
A. Covalent breakdown
B. Diffusion
C. Zener breakdown
D. Avalanche effect
106.
What are the two possible breakdown mechanisms in pn junction diodes?
A. Reverse and breakdown effects
B. Threshold and knee effects
C. Avalanche and forward effects
D. Zener and avalanche effects
107.
What factor is shown on a data sheet that tells how much you have to reduce the power of a device?
A. Power factor
B. Derating factor
C. Reactive factor
D. Reduction factor
PRACTICE PROBLEM ELEX SEMICONDUCTOR
108.
What factor(s) do(es) the barrier potential of a pn junction depend on?
A) type of semiconductive material
B) the amount of doping
C) the temperature
D) all of the above
109.
What electronic circuit converts AC to DC where the DC output peak value can be greater than the AC
input peak value?
A. Voltage multiplier
B. Rectifier
C. Clamper
D. Clipper
110.
Avalanche breakdown in a semiconductor takes place
A. When forward current exceeds a certain value
B. When potential barrier is reduced to zero
C. When reverse bias exceeds a certain value
D. When forward bias exceeds a certain value
111.
What device uses a material catwhisker as its anode and is classified as a hot-carrier diode?
A. PIN
B. Point-contact diode
C. Shockley diode
D. Crystal diode
112.
What is considered as the key electrical conductivity?
A. The number of electrons in the valence orbit
B. The number of protons in the nucleus
C. The number of neutrons in the nucleus
D. The number of protons plus the number of electrons in the atom
113.
The term bias in electronics usually means
A) the value of ac voltage in the signal.
B) the condition of current through a pn junction.
C) the value of dc voltages for the device to operate properly.
D) the status
114.
The holding of one extreme amplitude of the input waveform to a certain amount of potential is called
A. Slicing
B. Limiting
C. Rectifying
D. Clamping of the diode
115.
What refers to annihilation of a hole and electron?
A. Doping
B. Recombination
C. Diffusion
D. Bonding
116.
What type of diode is used for tuning receivers and is normally operated with reverse bias and derived
its name from voltage variable capacitor?
A. Hot-carrier diode
B. Varactor diode
C. Tunnel diode
D. Zener diode
117.
A silicon crystal is an intrinsic semiconductor
PRACTICE PROBLEM ELEX SEMICONDUCTOR
A. If every atom in the crystal is a silicon atom
B. If majority of the atoms in crystal is a silicon atom
C. If the crystal contains 14 silicon atoms
D. If the crystal is undoped
118.
A silicon diode measures a low value of resistance with the meter leads in both positions. The trouble, if
any, is
A) the diode is open.
B) the diode is shorted to ground.
C) the diode is internally shorted.
D) the diode is working correctly.
119.
What is the ideal value stability factor?
A. 1
B. 0.5
C. Infinite
D. 100
Fill in the blank
120.
The wide end arrow on a schematic indicates the __________ of a diode.
121.
A reverse-biased diode has the ______ connected to the positive side of the source, and the ______
connected to the negative side of the source.
122.
Single-element semiconductors are characterized by atoms with ____ valence electrons.
123.
For a forward-biased diode, as temperature is _____, the forward current _____ for a given value of
forward voltage.
124.
The peak inverse voltage of a half wave rectifier circuit is approximately equal to the ________ of the
input signal.
125.
For a forward-biased diode, the barrier potential _____ as temperature increases.
126.
An ideal diode presents a(n) _____ when reversed-biased and a(n) _____ when forward-biased.
127.
The most common type of diode failure is a(n) _____.
128.
The depletion width ________ in the forward bias, which results in having a majority flow across the
junction.
129.
The intensity of LED is greatest at ________ degrees and the least at ________ degrees.
130.
The ________ the current through a diode, the ________ the dc resistance level.
131.
The term ________ is often used when comparing the resistance level of materials
132.
Ge and Si have a(n) ________ coefficient in forward bias.
133.
The electrons in the largest orbit travel ________ than the electrons in the smaller orbits.
134.
For either germanium or silicon diodes, the barrier potential decreases _______ for each Celsius degree
rise.
135.
________ is a substance that contains atoms with several bands of electrons but with only one valence
electron.
PROBLEM SOLVING
136.
A dc voltage supply provides 60 V when the output is unloaded when connected to a load the out put
drops to 56. Calculate the value of voltage regulation.
137.
Calculate the ripple of a capacitor filter for a peak rectified voltage of 30V. Capacitor C=100 microfarad
and a load current of 50 mA.
138.
Determine what maximum dissipation will be allowed for an 80-W silicon transistor (rated at 25 percent)
if the reading is required above 25degree Celsius by derating factor of 0.5 W/degree Celsius at case temperature
of 125-degree Celsius.
PRACTICE PROBLEM ELEX SEMICONDUCTOR
139.
Calculate the filter DC voltage of a full wave rectifier with a 100-microfarad capacitor connected to a
load drawing 50 mA if the peak rectifier voltage is 30V.
140.
Calculate the ripple of a capacitor filter for a peak rectified voltage of 30V, capacitor C=100micro and a
load current of 50 mA.
141.
A Zener regulator has an input voltage that may vary from 22 to 30V. If the regulated output voltage is
12 V and the load resistance varies from 140K to 10K, what is the maximum allowable series resistance?
NAME EACH DIODE