MITRC – REFRESHER COURSE Basic Electronics, Diodes and Transistors

1. The atomic number of Silicon is 9. Although current is blocked in reverse bias

a. 8 a. there is some current due to majority
b. 2 carriers
c. 4 b. there is very small current due to
d. 14 minority carriers
c. there is avalanche CURRENT
2. Recombination is when d. there is lots of current due to majority of
a. an electron falls into a hole carriers
b. a positive and negative ion bond together
c. a valence electron becomes a conduction 10. A neutral dielectric has added to it 12.5 x 10 18
electron electrons, what is its charge in coulombs?
d. a crystal is formed a. -2
b. 2
3. Each atom in a silicon crystal has c. -3
a. four valence electrons d. 3
b. four conduction electrons
c. eight valence electrons, four of its own 11. The charge of 5 C moves past a given point
and four are shared in 1 s. How much is the current?
d. no valence electrons because all shared a. 5 A
with other atoms b. 0.2 A
c. 25 A
4. The process of adding an impurity to an d. .04 A
intrinsic semiconductor is called
a. doping 12. A carbon resistor is color coded with red, red,
b. recombination red and gold. What is the range of its resistance
c. atomic modification in ohms?
d. ionization a. 2090-2310
b. 20900- 23100
5. A trivalent impurity is added to silicon to create c. 1980- 2420
a. germanium d. 2100 -2300
b. an n-type semiconductor
c. a p-type semiconductor 13. It is the emission that causes a conductor to
d. a depletion region give off electrons at sufficiently high temperature.
a. thermionic
6. The purpose of a pentavalent impurity is to b. temperature
a. reduce the conductivity of the silicon c. high field
b. increase the number of holes d. secondary
c. increase the number of free electrons
d. create minority carriers 14. Diode vacuum tubes is popularly known as
________.
7. The term bias means a. Edison diode
a. the ratio of majority carriers to minority b. Fleming Bulb
carriers c. Edison Valve
b. the amount of current across a diode d. Fleming Valve
c. a dc voltage applied to control the
operation of the device 15. All vacuum tubes has this factor which is the
d. unfair tome required for an individual electron to travel
from the cathode to the plate of the tube.
8. When a diode is forward biased a. rise time
A. the only current is hole current b. pinch off time
b. the only current is electron current c. transit time
c. the only current is produced by majority d. traveling time
carriers
d. the current is produced by both holes
and electrons

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MITRC – REFRESHER COURSE Basic Electronics, Diodes and Transistors

16.The ________grid in an electron tube is 24. What effect does transit time have on
where the input signal is applied. conventional triode at UHF frequencies?
a. screen a. causes the plate to be shorted to the
b. control cathode
c. bias b. causes the control grid to be shorted
d. suppression to the cathode
c. causes the screen grid to be shorted to
17.________is a gaseous tube which uses a the cathode
poolol of liquid mercury as its cathode? d. the triode will be destroyed
a. thyratron
b. phanotron 25. This is a material usually graphite and is of
c. klystron high positive potential that attracts secondary
d. ignitron emitted electrons and removes them an also aid
sin the acceleration of electrons in a CRT.
18. What is the main reason why tetrode was a. accelerator grid
developed? b. cathode
a. space charge of triode c. aquadag
b. interelectrode capacitance of triode d. deflection plates
c. secondary emission of triode
d. all of the above 26.What is the fluorescent material in the CRT
screen that glows when struck by electron
19. A vacuum tube element that control the flow beams?
of plate current. a. aquadag
a. cathode b. phosphorus
b. heater c. LCD
c. control grid d. phosphor
d. anode
27. Structurally, what are the two main categories
20. What undesirable effect does the screen grid of semiconductor diode?
in the tetrode create? a. Junction and point contact
a. secondary emission b. Electrolytic and junction
b. thermionic emission c. Electrolytic and point contact
c. interelectrode capacitance d. Vacuum and point contact
d. space charge
28. The bulk resistance of a diode is_____
21. Electron flow within the vacuum tube diode is a. the resistance of N-material only
always b. the resistance of P material only
a. from cathode to anode c. the resistance of the junction only
b. from cathode to plate d. the resistance of the P and the N
c. from plate to cathode material
d. from anode to cathode
29. A silicon diode has a forward voltage drop of
22. In triode, the inter-electrode capacitance 1.2V for a forward DC current of 100 mA. With a
feeds back energy from the output to the input reverse current of 1 µA . Calculate the bulk
circuit? resistance?
a. grid to cathode capacitance a. 5 ohms
b. grid to plate capacitance b. 12 ohms
c. plate to cathode capacitance c. 19 ohms
d. all of these d. 1.2 Mohms

23. What is the tube that has 2 grids? 30. What are the two primary classifications of
a. vacuum tube diode Zener diodes?
b. triode a. Hot carrier and tunnel
c. tetrode b. Varactor and rectifying
d. pentode c. Voltage regulator and voltage
reference
d. Forward and reversed biased

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MITRC – REFRESHER COURSE Basic Electronics, Diodes and Transistors

38. It is a special type of diode that has no

31. What is the principal characteristic of a Zener depletion layer thereby eliminating the stored
diode? charges between junction.
a. A constant current under conditions of a. zener diode
varying voltage b. Schottky diode
b. A constant voltage under conditions c. Tunnel diode
of varying current d. back diode
c. A negative resistance region
d. An internal capacitance that varies with 39. Tunnel diode has the thinnest depletion layer
the applied voltage and is very popular because of this phenomenon.
a. positive resistance
32. What is the range of voltage ratings available b. negative resistance
in Zener diodes? c. inverted resistance
a. 2.4 volts to 200 volts d. bulk resistance
b. 1.2 volts to 7 volts
c. 3 volts to 2000 volts 40. It is the process involved when large surface
d. 1.2 volts to 5.6 volts area on one layer of one semiconductive material
permits the photons to be emitted as visible light.
33. What is the principal characteristic of a tunnel a. Photoluminescense
diode? b. Electroluminescense
a. A high forward resistance c. Extraluminescence
b. A very high PIVC d. Luminance
c. A negative resistance region
d. A high forward current rating 41. What is a common use of a hot-carrier diode?
a. As balanced mixers in SSB generation
34. What special type of diode is capable of both b. As a variable capacitance in an automatic
amplification and oscillation? frequency control circuit
a. Point contact diodes c. As a constant voltage reference in a power
b. Zener diodes supply
c. Tunnel diodes d. As VHF and UHF mixers and detectors
d. Junction diodes
42. What limits the maximum forward current in a
35. What type of semiconductor diode varies its junction diode?
internal capacitance as the voltage applied to its a. The peak inverse voltage
terminals varies? b. The junction temperature
a. A varactor diode c. The forward voltage
b. A tunnel diode d. The back EMF
c. A silicon-controlled rectifier
d. A Zener diode 43. How are junction diodes rated?
a. Maximum forward current and capacitance
36. What is the principal characteristic of a b. Maximum reverse current and PIV
varactor diode? c. Maximum reverse current and capacitance
a. It has a constant voltage under d. Maximum forward current and PW
conditions of varying current
b. Its internal capacitance varies with the 44. What is a common use for point contact
applied voltage diodes?
c. It has a negative resistance region a. As a constant current source
d. It has a very high PIV b. As a constant voltage source
c. As an RF detector
37. What is a common use of a varactor diode? d. As a high voltage rectifier
a. As a constant current source
b. As a constant voltage source 45. What type of diode is made of a metal
c. As a voltage-controlled inductance whisker touching a very small semiconductor
d. As a voltage-controlled capacitance die?
a. Zener diode
b. Varactor diode
c. Junction diode

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MITRC – REFRESHER COURSE Basic Electronics, Diodes and Transistors

d. Point-contact diode b. cut-off

c. shorted
46. What is one common use for PIN diodes? d. shunted
a. As a constant current source
b. As a constant voltage source 54. What are the three terminals of a bipolar
c. As an RF switch transistor?
d. As a high voltage rectifier a. Cathode, plate and grid
b. Base, collector and emitter
47. What special type of diode is often used in c. Gate, source and sink
RF switches, attenuators, and various types of d. Input, output and ground
phase shifting devices?
a. Tunnel diodes 55. The transistor is usually encapsulated in
b. Varactor diodes a. graphite powder
c. PIN diodes b. enamel paint
d. Junction diodes c. epoxy raisin
d. black plastic
48. The most widely used rectifier circuit is
______. 56. The operation of pnp transistor differs that of
a. half wave the npn in which of the ff:
b. center tap 1. The roles of the electrons and holes
c. bridge type 2. Bias voltage polarities
d. book type 3. Current directions are all reversed.
4. Three transistor terminals.
49. The _______filter circuit results in the best a. 1, 2 and 3 only
voltage regulation b. 1 and 2 only
a. choke input c. 2, 3 and 4 only
b. capacitor input d. 1, 2, 3 and 4
c. resistant input
d. transformer input 57. For BJT, the term bipolar refers to ____.
a. the use of both holes and electrons as
50. A 60 Hz sine voltage is applied to the input of carriers in transistor.
a half wave rectifier, what is the output b. the emitter and collector as terminals.
frequency? c. the anode and cathode as terminals.
a. 60 Hz d. the direction of current in the transistor
b. 120 Hz
c. 30 Hz 58. It is the most lightly doped BJT region.
d. 180 Hz a. emitter
b. collector
51. If you are checking a 60 Hz full-wave bridge c. base
rectifier and observe that the output has a 60 Hz d. gate
ripple,
a. the circuit is working properly 59. A transistor is also limited on its operation.
b. the transformer secondary is shorted These limitations are stated in the manufacturer’s
c. there is an open diode data sheet in the form of maximum ratings which
d. the filter capacitor is leaky typically includes maximum rating for:
1. collector-to-base voltage
52. How many diodes does a bridge circuits 2. collector-to-emitter voltage
require? (April, 2004) 3. emitter-to-base voltage
a. two diodes 4. collector current
b. three diodes 5. power dissipation
c. five diodes a. 1 ,2 ,3 only
d. four diodes b. 1, 2 ,3 and 4 only
c. 1, 2, 3 and 5 only
53. What is the condition of the diode in a series d. 1 ,2 ,3 ,4 and 5
–limiter when the output is developed?
(November, 2003) 60. What is the meaning of the term alpha with
a. conducting regard to bipolar transistors?

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MITRC – REFRESHER COURSE Basic Electronics, Diodes and Transistors

a. The change of collector current with 66. What is the meaning of the term beta cutoff
respect to base current frequency with regard to a bipolar transistor?
b. The change of base current with respect to a. That frequency at which the grounded
collector current base current gain has decreased to 0.7 of
c. The change of collector current with that obtainable at 1 kHz in a transistor
respect to emitter current b. That frequency at which the grounded
d. The change of collector current with emitter current gain has decreased to 0.7
respect to gate current of that obtainable at 1 kHz in a transistor
c. That frequency at which the grounded
61. What is the term used to express the ratio of collector current gain has decreased to 0.7 of
change in DC collector current to a change in that obtainable at 1 kHz in a transistor
emitter current in a bipolar transistor? d. That frequency at which the grounded gate
a. Gamma current gain has decreased to 0.7 of that
b. Epsilon obtainable at 1 kHz in a transistor
c. Alpha
d. Beta 67. What is the meaning of the term transition
region with regard to a transistor?
62. What is the meaning of the term beta with a. An area of 10 W charge density
regard to bipolar transistors? around the P-N junction
a. The change of collector current with b. The area of maximum P-type charge
respect to base current c. The area of maximum N-type charge
b. The change of base current with respect to d. The point where wire leads are
emitter current connected to the P- or N-type material
c. The change of collector current with
respect to emitter current 68. What does it mean for a transistor to be fully
d. The change in base current with respect to saturated?
gate current a. The collector current is at its
maximum value
63. What is the term used to express the ratio of b. The collector current is at its minimum
change in the DC Collector current to a change in value
base current in a bipolar transistor? c. The transistor’s Alpha is at its maximum
a. Alpha value
b. Beta d. The transistor’s Beta is at its maximum
c. Gamma value
d. Delta
69. What does it mean for a transistor to be cut
64. What is the meaning of the term alpha cut-off off?
frequency with regard to bipolar transistors? a. There is no base current
a. The practical lower frequency limit of a b. The transistor is at its operating point
transistor in common emitter configuration c. No current flows from emitter to
b. The practical upper frequency limit of a collector
transistor in common base configuration d. Maximum current flows from emitter to
c. The practical lower frequency limit of a collector
transistor in common base configuration
d. The practical upper frequency limit of a 70. What are the elements of a unijunction
transistor in common emitter configuration transistor?
a. Base 1, base 2 and emitter
65. What is the term used to express that b. Gate, cathode and anode
frequency at which the grounded base current c. Gate, base 1 and base 2
gain has decreased to 0.7 of the gain obtainable d. Gate, source and sink
at 1 kHz in a transistor?
a. Corner frequency 71. For best efficiency and stability, where on the
b. Alpha cutoff frequency load-line should a solid-state power amplifier be
c. Beta cutoff frequency operated?
d. Alpha rejection frequency a. Just below the saturation point
b. Just above the saturation point
c. At the saturation point

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MITRC – REFRESHER COURSE Basic Electronics, Diodes and Transistors

d. At 1.414 times the saturation d. An FET without a channel; no current

occurs with zero gate voltage
72. What two elements widely used in
semiconductor devices exhibit both metallic and 79. What do you call the layer that is adjacent to
non-metallic characteristics? the SiO2 that serves as connection layer for the
a. Silicon and gold drain and gate terminals for an E-MOSFET when
b. Silicon and germanium properly biased?
c. Galena and germanium a. inverted layer
d. Galena and bismuth b. inversion layer
c. channel
73. What is the normal operating voltage and d. catastrophic layer
current for a light-emitting diode?
a. 60 volts and 20 mA 80. What is a depletion-mode FET?
b. 5 volts and 50 mA a. An FET that has a channel with no
c. 1.7 volts and 20mA gate voltage applied; a current lows
d. 0.7 volts and 60 mA with zero gate voltage
b. An FET that has a channel that blocks
74. What type of bias is required for an LED to current when the gate voltage is zero
produce luminescence? c. An FET without a channel; no current
a. Reverse bias flows with zero gate voltage
b. Forward bias d. An FET without a channel to hinder
c. Zero bias current through the gate
d. Inductive bias
81. Why do many MOSFET devices have built-in
75. What are the advantages of using an LED? gate-protective Zener diodes?
a. Low power consumption and long life a. The gate-protective Zener diode provides
b. High lumens per cm per cm and low a voltage reference to provide the correct
power consumption amount of reverse-bias gate voltage
c. High lumens per cm per cm and low b. The gate-protective Zener diode protects
voltage requirement the substrate from excessive voltages
d. A current flows when the device is c. The gate-protective Zener diode keeps
exposed to a light source the gate voltage within specifications to
prevent the device from overheating
76. What colors are available in LEDs? d. The gate-protective Zener diode
a. Yellow, blue, red and brown prevents the gate insulation from
b. Red, violet, yellow and peach being punctured by small static
c. Violet, blue, orange and red charges or excessive voltages
d. Red, green, orange and yellow
82. What do the initials CMOS stand for?
77. How can a neon lamp be used to check for a. Common mode oscillating system
the presence of RF? b. Complementary mica-oxide silicon
a. A neon lamp will go out in the presence c. Complementary metal-oxide
of RF semiconductor
b. A neon lamp will change color in the d. Complementary metal-oxide substrate
presence of RF
c. A neon lamp will light only in the 83. Why are special precautions necessary in
presence of very low frequency RF handling FET and CMOS devices?
d. A neon lamp will light in the presence a. They are susceptible to damage from
of RF static charges
b. They have fragile leads that may break
78. What is an enhancement-mode FET? off
a. An FET with a channel that blocks c. They have micro-welded semiconductor
voltage through the gate junctions that are susceptible to
b. An FET with a channel that allows a breakage
current when the gate voltage is zero d. They are light sensitive
c. An FET without a channel to hinder
current through the gate

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MITRC – REFRESHER COURSE Basic Electronics, Diodes and Transistors

84. How does the input impedance of a field- 91. A JFET just operates with specifically
effect transistor compare with that of a bipolar a. the drain connected to ground
transistor? b. gate to source PN junction forward biased
a. One cannot compare input impedance c. gate connected to the source
without first knowing the supply voltage d. gate to source PN junction reverse
b. An FET has low input impedance; a biased
bipolar transistor has high input impedance
c. The input impedance of FETs and bipolar 92. The main difference of a MOSFET from a
transistors is the same JFET is that
d. An FET has high input impedance; a a. JFET has PN junction
bipolar transistor has low input b. of the power rating
impedance c. MOSFETS has two gates
d. MOSFETs do not have physical channel
85. What are the three terminals of a field-effect
transistor? 93. A small signal amplifier
a. Gate 1, gate 2, drain a. uses only a small portion of its loadline
b. Emitter, base, collector b. always has an output signal in the mV
c. Emitter, base 1, base 2 range
d. Gate, drain, source c. goes into saturation once on each input
cycle
86. What are the two basic types of junction field- d. is always a common emitter amplifier
effect transistors?
a. N-channel and P-channel 94. If the DC emitter current in a certain transistor
b. High power and low power amplifier is 3 mA, the approximate value of r’e is
c. MOSFET and GaAs FET a. 3KΩ
d. Silicon FET and germanium FET b. 3Ω
c. 8.33 Ω
87. Which of the following is expected to have the d. 0.33 KΩ
highest input impedance?
a. MOSFET 95. The maximum efficiency of a transformer
b.JFET amplifier coupled Class A amplifier is__.
c. CE bipolar transistor a. 25
d. CC bipolar transistor b. 50
c. 78.5
88.The ______is quite popular in digital circuits d. 100
especially in CMOS which require very low power
consumption. 96. In a MOSFET, the process of creating a
a. JFET channel by the addition of charge carrier is
b. BJT called.
c. D-type MOSFET a. inducement
d. E-type MOSFET b. improvement
c. balancing
89. What is the amplification factor in FET d. enhancement
transistor amplifiers?
a. Zi 97. In a common –base amplifier the voltage gain
b. gm is_____.(April, 2003)
c. ID a. medium
d. IG b. low
c. zero
90. The E-MOSFET is quite popular in what type d. high
of applications.
a. digital circuitry 98. In a common collector amplifier, the input
b. high frequency resistance is___.(Nov,2003)
c.buffering a. high
d. a, b and c b. zero
c. medium
d. low

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MITRC – REFRESHER COURSE Basic Electronics, Diodes and Transistors

99. What problem is caused by a loosely

coupled transformer in an RF amplifier? (April, 107. What type of crystal exhibit the highest
2004) piezoelectric activity?
a. a too narrow bandpass a. tourmaline
b. over coupling b. Rochelle salt
c. optimum coupling c. diamond
d. a too-wide bandpass d. quartz crystal

100. Normally, how are high power tubes tested 108. Blocking oscillator are used as
(April, 2004) a. abrupt pulse generator
a. visually b. high impedance switches
b. individually c. low impedance switches
c. in their circuit d. signal generator
d. use portable testers
109. A phase shift oscillator consist of number of
101. What is a CMOS IC? a. RC circuits
a. A chip with only P-channel transistors b. RL circuits
b. A chip with P-channel and N-channel c. LC circuits
transistors d. FET circuits
c. A chip with only N-channel transistors
d. A chip with only bipolar transistors 110. To sustain oscillations, circuits must exhibit
a. hall effect
102. Who developed negative feedback? b. fly effect
a. Harold Black c. flywheel effect
b. Herald Black d. shake effect
c. Ronald Black
d. Blackdyak 111. A monostable multivibrator can be used to
generate
103. A portion of the output is taken and is a. sweep
connected in the input. b. pulse
a. feedback systems c. sinusoids
b. amplifers d. DC
c. clampers
d. clippers 112. The main feature of crystal oscillator is
a. economy
104. This type of feedback increases the gain of b. reliability
the system c. stability
a. positive feedback d. high frequency
b. negative feedback
c. degenerative feedback 113. In a certain oscillator, Av = 50, the
d. zero feedback attenuation of the feedback circuit must
be______.
105. A circuit capable of providing a repetitive a. 1
output wave from an externally generated input b. 0.01
signal c. 10
a. amplifier d. 0.02
b. oscillator
c. feedback 114. An oscillator differs from an amplifier
d. regulator because
a. it has more gain
106. What do you call the phenomenon that a b. it requires no DC supply
mechanical stress produces a potential difference c. it requires no input signal
across the opposite faces of crystals? d. it always has the same output
a. photoelectric effect
b. piezoelectric effect 115. Wien Bridge oscillators are based on
c. mechatronics effect a. positive feedback
d hall effect b. the piezoelectric effect

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MITRC – REFRESHER COURSE Basic Electronics, Diodes and Transistors

c. negative feedback c. decreased

d. high gain d. equals infinity

116. For an oscillator to properly start, the gain 124. An oscillator always needs an amplifier with
around the feedback loop must initially be a. Positive feedback
a. 1 b. Negative feedback
b. less than 1 c. Degenerative feedback
c. greater than 1 d. all of the above
d. equal to β
125. An RC phase shift oscillator
117. The loop gain in a phase shift oscillator must uses______amplifier.
be___degrees a. Class A
a. 45 b. Class B
b. 90 c. Class C
c. 180 d. Class AB
d. 360
126. A Wien Bridge oscillator is sometimes called
118. An oscillator using a capacitive voltage a___________.
divider to provide feedback. a. Trap
a. Hartley b. Band pass filter
b. Colpitts c. Phase shifter
c. Armstrong d. Wheatstone bridge
d. Phase shift
127. _______damping is the progressive decay
119. The oscillator with the best frequency with time in the amplitude of the free oscillation in
stability and accuracy a circuit.
a. Hartley a. decrement
b. Colpitts b. pulse decay time
c. Clapp c. damping
d. Crystal-controlled d. transient

120. An oscillator circuit is mainly 128. Link coupling is also called

a. DC to AC converter a. capacitive coupling
b. DC to DC converter b. transformer coupling
c. AC to DC converter c. resistive coupling
d. AC to AC converter d. power coupling

121. If the gain of an amplifier without feedback is 129. The kind of oscillator found in an electronic
10 and with negative feedback is 8, then the wristwatch is the
feedback fraction is a. Armstrong
a. 0.25 b. Clapp
b. 0.9 c. Colpitts
c. 0.8 d. Quartz crystal
d. 0.225
130. Which of the following minerals provides
122. The gain with negative feedback is the highest piezoelectric effect?
approximately ______when the feedback fraction a. Tourmaline
is 0.01. b. Rochelle Salt
a. 10 c. Quartz
b. 100 d. Diamond
c. 500
d. 1000 131. A microwave oscillator is
a. Hartley oscillator
123. What happens to the input resistance of an b. Colpitts oscillator
amplifier employing current-shunt feedback? c. Relaxation oscillator
a. increased d. Klystron oscillator
b. remains the same

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MITRC – REFRESHER COURSE Basic Electronics, Diodes and Transistors

132. Type of oscillator whose frequency is

dependent on the charge and discharge of the
RC networks.
a. Hartley oscillator
b. Colpitts oscillator
c. Relaxation oscillator
d. Klystron oscillator

133. An RC phase shift oscillator has a 52 ohms

feedback resistance in each branch and 10 µF
capacitance in each branch. What is its resonant
frequency?
a. 125 Hz
b. 306 Hz
c. 25 MHz
d. 100 KHz

134. It is a feedback oscillator that uses

transformer coupling to fed back portion of the
input signal
a. Hartley
b. Colpitts
c. Armstrong
d. Clapp

135. Crystals have a very

a. low Q
b. high Q
c. small inductance
d. large resistance

10 Feedbacks and Oscillators