Semiconductors 1 . Single-element semiconductors are characterized by atoms with ____ valence electrons. A . 3 B . 4 C . 5 D . 2 E . none of the above 2 . Under normal conditions a diode conducts current when it is A . reverse-biased. B . forward-biased. C . avalanched. D . saturated. 3 . 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 4 . As the forward current through a silicon diode increases, the internal resistance
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Semiconductors
1. Single-element semiconductors are characterized by atoms with ____ valence electrons.A.3B.4C.5D.2E.none of the above
2. Under normal conditions a diode conducts current when it isA.reverse-biased. B.forward-biased.C.avalanched. D.saturated.
3. A diode conducts when it is forward-biased, and the anode is connected to the ________ through a limiting resistor.A.positive supplyB.negative supplyC.cathodeD.anode
4. As the forward current through a silicon diode increases, the internal resistanceA.increases.B.decreases.C.remains the same.
5. For a forward-biased diode, the barrier potential ________ as temperature increases.A.decreasesB.remains constantC.increases
6. An n-type semiconductor materialA.is intrinsic.B.has trivalent impurity atoms added.C.has pentavalent impurity atoms added.D.requires no doping.
7. For a forward-biased diode, as temperature is ________, the forward current ________ for a given value of forward voltage.A.decreased, increasesB.increased, increasesC.increased, decreasesD.decreased, decreases
08. 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.
09. You have an unknown type of diode in a circuit. You measure the voltage across it and find it to be 0.3 V. The diode might beA.
10. What types of impurity atoms are added to increase the number of conduction-band electrons in intrinsic silicon?A.
bivalent
B.octavalentC.
pentavalent
D.
trivalent
E.none of the above
11. What factor(s) do(es) the barrier potential of a pn junction depend on?A.
type of semiconductive material
B.the amount of dopingC.the temperatureD.
all of the above
E. type of semiconductive material and the amount of doping but not the temperature
12. Reverse breakdown is a condition in which a diodeA.
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.
13. What occurs when a conduction-band electron loses energy and falls back into a hole in the valence band?A.
doping B.recombination
C.generation D.[NIL]
Diode Applications
14. Each diode in a center-tapped full-wave rectifier is ________ -biased and conducts for ________ of the input cycle.
A.
forward, 90º
B.reverse, 180ºC.
forward, 180º
D.
reverse, 90º
15. The output frequency of a full-wave rectifier is ________ the input frequency.A.
one-half
B.equal toC.
twice
D.
one-quarter
16. PIV is which of the following?A.
peak input voltage
B.peak inverse voltageC.peak immediate voltageD.
positive input voltage
17. If the ac supply is 50 Hz, what will be the ripple frequency out of the full-wave rectifier?A.
50 Hz
B.60 HzC.
100 Hz
D.
120 Hz
18. A silicon diode in a half-wave rectifier has a barrier potential of 0.7 V. This has the effect ofA.
reducing the peak output voltage by 0.7 V.
B.increasing the peak output voltage by 0.7 V.C.reducing the peak input voltage by 0.7 V.D no effect.
.
19. If the ac supply is 60 Hz, what will be the ripple frequency out of the half-wave rectifier?A.
30 Hz
B.50 HzC.
60 Hz
D.
120 Hz
20. In the operation of a half-wave rectifier with a capacitor-input filter, the ripple factor can be lowered by ________ the value of the filter capacitor or ________ the load resistors.A.
Bjt DEVICES21. How much is the base-to-emitter voltage of a transistor in the "on" state?
A.
0 V
B.0.7 VC.0.7 mVD.
Undefined
22. For what kind of amplifications can the active region of the common-emitter configuration be used?A.
Voltage
B.CurrentC.PowerD.
All of the above
23. In the active region, while the collector-base junction is ________-biased, the base-emitter is ________-biased.A.
forward, forward
B.forward, reverseC.
reverse, forward
D.
reverse, reverse
24. What range of resistor values would you get when checking a transistor for forward- and reverse-biased conditions by an ohmmeter?A.
100 to a few k , exceeding 100 k
B.Exceeding 100 k , 100 to a few kC.Exceeding 100 k , exceeding 100 kD.
100 to a few k , 100 to a few k
25. In which region are both the collector-base and base-emitter junctions forward-biased?A.
Active
B.CutoffC.
Saturation
D.
All of the above
26. What does a reading of a large or small resistance in forward- and reverse-biased conditions indicate when checking a transistor using an ohmmeter?A.
Faulty device
B.Good deviceC.Bad ohmmeterD.
None of the above
27. Determine the value of when = 100.
A 1.01
.B.101C.
0.99
D.
Cannot be solved with the information provided
28. dc = ________A.
IB / IE
B.IC / IE
C.
IC / IB
D.
None of the above
29. How many carriers participate in the injection process of a unipolar device?A.
1 B.2
C.0 D.3
30. What are the ranges of the ac input and output resistance for a common-base configuration?A.
10 –100 , 50 k –1 M
B.50 k –1 M , 10 –100 C.10 –100 k , 50 –1 kD.
None of the above
31. What is the most frequently encountered transistor configuration?A.
Common-base B.Common-collector
C.
Common-emitter D.Emitter-collector
Field-Effect Transistors32. For a JFET, the value of VDS at which ID becomes essentially constant is the
A pinch-off voltage.
.B.cutoff voltage.C.breakdown voltage.D.
ohmic voltage.
33. The ________ has a physical channel between the drain and source.A.
D-MOSFET B.E-MOSFET
C.V-MOSFET D.[NIL]
34. What type(s) of gate-to-source voltage(s) can a depletion MOSFET (D-MOSFET) operate with?A.
zero
B.positiveC.negativeD.
any of the above
35. Midpoint bias for a D-MOSFET is ID = ________, obtained by setting VGS = 0.A.
IDSS / 2
B.IDSS / 3.4C.
IDSS
36. On the drain characteristic curve of a JFET for VGS = 0, the pinch-off voltage isA.
below the ohmic area.
B.between the ohmic area and the constant current area.C.between the constant current area and the breakdown region.D.
above the breakdown region.
37. Which of the following devices has the highest input resistance?A.
diode
B.JFETC.
MOSFET
D.
bipolar junction transistor
38. The value of VGS that makes ID approximately zero is theA.
pinch-off voltage.
B.cutoff voltage.C.breakdown voltage.D.
ohmic voltage.
39. A dual-gated MOSFET isA.
a depletion MOSFET.
B.an enhancement MOSFET.C.a VMOSFET.D.
either a depletion or an enhancement MOSFET.
40. What three areas are the drain characteristics of a JFET (VGS = 0) divided into?A.
65. In what range of voltages is the transistor in the linear region of its operation?
A.
0 < VCE
B.0.7 < VCE < VCE(max)
C.VCE(max) > VCE
D.
none of the above
66. The magnitude of dark current in a phototransistor usually falls in what range?A.
mA B.μA
C nA D.pA
.
67. The dc load line on a family of collector characteristic curves of a transistor shows theA.
saturation region.
B.cutoff region.C.active region.D.
all of the above
FET Devices
69. What is the level of IG in an FET?A.
Zero amperes
B.Equal to ID
C.Depends on VDS
D.
Undefined
70. What is the range of an FET's input impedance?A.
10 to 1 k
B.1 k to 10 kC.50 k to 100 kD.
1 M to several hundred M
71. Which of the following controls the level of ID?A.
VGS B.VDS
C.IG D.VDG
72. It is the insulating layer of ________ in the MOSFET construction that accounts for the very
desirable high input impedance of the device.A.
SiO B.GaAs
C.
SiO2 D.HCl
73. The BJT is a ________ device. The FET is a ________ device.A.
bipolar, bipolar
B.bipolar, unipolarC.unipolar, bipolarD.
unipolar, unipolar
74. The transfer curve is not defined by Shockley's equation for the ________.
A.
JFET
B.depletion-type MOSFETC.
enhancement-type MOSFET
D.
BJT
75. The region to the left of the pinch-off locus is referred to as the ________ region.A.
saturation
B.cutoffC.
ohmic
D.
All of the above
76. A BJT is a ________-controlled device. The JFET is a ________ - controlled device.A.
voltage, voltage
B.voltage, currentC.
current, voltage
D.
current, current
77. Which of the following FETs has the lowest input impedance?A.
JFET
B.MOSFET depletion-typeC.MOSFET enhancement-type
D.
None of the above
78. Which of the following applies to MOSFETs?A.
No direct electrical connection between the gate terminal and the channel
B.Desirable high input impedanceC.Uses metal for the gate, drain, and source connectionsD.
All of the above
79. At which of the following is the level of VDS equal to the pinch-off voltage?A.
When ID becomes equal to IDSS
B.When VGS is zero voltsC.IG is zeroD.
All of the above
80. Which of the following input impedances is not valid for a JFET?A.
1010
B.109 C.
108
D.
1011
Special-Purpose Diodes81. Schottky diodes are also known as
A.
PIN diodes.
B.hot carrier diodes.C.step-recovery diodes.D.
tunnel diodes.
82. Zener diodes with breakdown voltages less than 5 V operate predominantly in what type of
breakdown?A.
avalanche B.zener
C.varactor D.Schottky
83. The Schottky diode is usedA.
in high-power circuits.
B.in circuits requiring negative resistance.C.
in very fast-switching circuits.
D.
in power supply rectifiers.
84. You have an application for a diode to be used in a tuning circuit. A type of diode to use might beA.
an LED.
B.a Schottky diode.C.a Gunn diode.D.
a varactor.
85. What kind of diode is formed by joining a doped semiconductor region with a metal?A.
laser B.tunnel
C.pin D.Schottky
86. Which diode employs graded doping?A.
zener B.LED
C.tunnel D.step-recovery
87. LEDs are made out ofA.
silicon.
B.germanium.C Gallium Arsenide.
.D.
silicon and germanium, but not gallium.
88. The normal operating region for a zener diode is theA.
forward-bias region.
B.reverse-bias region.C.zero-crossing region.D.
reverse-breakdown region.
89. The process of emitting photons from a semiconductive material is calledA.
photoluminescence.
B.gallium arsenide.C.
electroluminescence.
D.
gallium phosphide.
90. What type of diode maintains a constant current?A.
LED
B.zenerC.
current regulator
D.
pin
E.none of the above
91. Back-to-back varactor diodes are used for what reason?A.
over-voltage protection
B.a wider tuning rangeC.
to eliminate harmonic distortion
D.
no reason; only zeners are used in a back-to-back configuration
92. A tunnel diode is usedA.
in high-power circuits.
B.in circuits requiring negative resistance.C.in very fast-switching circuits.D.
in power supply rectifiers.
93. A laser diode normally emitsA.
coherent light.
B.monochromatic light.C.
coherent and monochromatic light.
D.
neither coherent nor monochromatic light.
Thyristors94. The ________ can be externally programmed to turn on at a desired anode-to-gate voltage
level.A.
UJT B.PUT
C.SCR D.SCS
95. The silicon-controlled switch (SCS) is similar in construction to theA.
triac.
B.diac.C.
SCR.
D.
4-layer diode.
96. The ________ can conduct current in either direction and is turned on when a breakover
voltage is exceeded.A.
SCR B.diac
C.SCS D.triac
97. You need to design a relaxation oscillator circuit. The most likely device to use might beA.
an SCR.
B.a UJT.C.a triac.D.
a 4-layer diode.
98. You have the schematic diagram of several types of circuits. Which of these circuits most likely uses a triac?A.
an oscillator
B.an ac motor controlC.a programmable oscillatorD.
an amplifier
99. The SCR can be triggered on by a pulse at theA.gate.B.anode.C.cathode.D.none of the above
100. How many semiconductor layers are thyristors constructed with?A.2 B.3C.4 D.5
101. Your boss has asked you to recommend a thyristor that will enable you to turn it on with a pulse and also turn it off with a pulse. Which of the following should you recommend?A.an SCRB.an SCSC.a PUTD.a triac