semicon & diodes Flashcards
Intrinsic semiconductor material is characterized by a valence shell of how many electrons?
1
2
4
6
4
Ionization within a P-N junction causes a layer on each side of the barrier called the:
junction
depletion region
barrier voltage
forward voltage
depletion region
What is the most significant development in electronics since World War II?
the development of color TV
the development of the diode
the development of the transistor
the development of the TRIAC
the development of the transistor
What causes the depletion region?
doping
diffusion
barrier potential
ions
diffusion
What is an energy gap?
the space between two orbital shells
the energy equal to the energy acquired by an electron passing a 1 V electric field
the energy band in which electrons can move freely
an energy level at which an electron can exist
the space between two orbital shells
Silicon atoms combine into an orderly pattern called a:
covalent bond
crystal
semiconductor
valence orbit
crystal
In “n” type material, majority carriers would be:
holes
dopants
slower
electrons
electrons
Elements with 1, 2, or 3 valence electrons usually make excellent:
conductors
semiconductors
insulators
neutral
conductors
A commonly used pentavalent material is:
arsenic
boron
gallium
neon
arsenic
Which material may also be considered a semiconductor element?
carbon
ceramic
mica
argon
carbon
In “p” type material, minority carriers would be:
holes
dopants
slower
electrons
electrons
What can a semiconductor sense?
magnetism
temperature
pressure
all of the above
all of the above
When an electron jumps from the valence shell to the conduction band, it leaves a gap. What is this gap called?
energy gap
hole
electron-hole pair
recombination
hole
Forward bias of a silicon P-N junction will produce a barrier voltage of approximately how many volts?
0.2
0.3
0.7
0.8
0.7
Which semiconductor material is made from coal ash?
germanium
silicon
tin
carbon
germanium
When and who discovered that more than one transistor could be constructed on a single piece of semiconductor material:
1949, William Schockley
1955, Walter Bratten
1959, Robert Noyce
1960, John Bardeen
1959, Robert Noyce
When is a P-N junction formed?
in a depletion region
in a large reverse biased region
the point at which two opposite doped materials come together
whenever there is a forward voltage drop
the point at which two opposite doped materials come together
A P-N junction mimics a closed switch when it:
has a low junction resistance
is reverse biased
cannot overcome its barrier voltage
has a wide depletion region
has a low junction resistance
Solid state devices were first manufactured during:
World War 2
1904
1907
1960
1960
Electron pair bonding occurs when atoms:
lack electrons
share holes
lack holes
share electrons
share electrons
How many valence electrons are in every semiconductor material?
1
2
3
4
4
What is a type of doping material?
extrinsic semiconductor material
pentavalent material
n-type semiconductor
majority carriers
pentavalent material
Minority carriers are many times activated by:
heat
pressure
dopants
forward bias
heat
What is the voltage across R1 if the P-N junction is made of silicon?
12 V
11.7 V
11.3 V
0 V
11.3 V
If conductance increases as temperature increases, this is known as a:
positive coefficient
negative current flow
negative coefficient
positive resistance
negative coefficient
Which of the following cannot actually move?
majority carriers
ions
holes
free electrons
ions
What electrical characteristic of intrinsic semiconductor material is controlled by the addition of impurities?
conductivity
resistance
power
all of the above
Conductivity
What is a varistor?
a voltage-dependent resistor
a voltage-dependent diode
a current-dependent resistor
a current-dependent diode
a voltage-dependent resistor
Which type of transformer is required to create a 180 degree input to a rectifier?
center-tapped secondary
step-down secondary
stepped-up secondary
split winding primary
center-tapped secondary
What circuit activity may shift a characteristic curve so that diode operating points are different?
higher power (heat)
higher resistance
lower voltage
lower current
higher power (heat)
The dc current through each diode in a bridge rectifier equals:
the load current
half the dc load current
twice the dc load current
one-fourth the dc load current
the load current
When matching polarity connections have been made and the potential difference (PD) is above 0.7 V, the diode is considered to be:
not working
forward biased
reverse biased
an open switch
forward biased
In a power supply diagram, which block indicates a smooth dc output?
transformer
filter
rectifier
regulator
regulator
The characteristic curve for the complex model of a silicon diode shows that
the barrier potential is 0 V
the barrier potential stays fixed at 0.7 V
the barrier potential increases slightly with an increase in current
the barrier potential decreases slightly with an increase in current
the barrier potential increases slightly with an increase in current
Since diodes are destroyed by excessive current, circuits must have:
higher voltage sources
current limiting resistors
more dopants
higher current sources
current limiting resistors
A diode for which you can change the reverse bias, and thus vary the capacitance is called a
varactor diode
tunnel diode
zener diode
switching diode
varactor diode
A filtered full-wave rectifier voltage has a smaller ripple than does a half-wave rectifier voltage for the same load resistance and capacitor values because:
there is a shorter time between peaks
there is a longer time between peaks
the larger the ripple, the better the filtering action
none of the above
there is a shorter time between peaks
Testing a good diode with an ohmmeter should indicate
high resistance when forward or reverse biased
low resistance when forward or reverse biased
high resistance when reverse biased and low resistance when forward biased
high resistance when forward biased and low resistance when reverse biased
high resistance when reverse biased and low resistance when forward biased
The peak inverse voltage (PIV) across a nonconducting diode in a bridge rectifier equals approximately:
half the peak secondary voltage
twice the peak secondary voltage
the peak value of the secondary voltage
four times the peak value of the secondary voltage
the peak value of the secondary voltage
Electrons in the outermost orbit or shell of an atom are called
free electrons
negative ions
valence electrons
conduction band electrons
valence electrons
Shunting the ac component away from the load is the task of a:
transformer
filter
regulator
rectifier
filter
A pn junction allows current flow when
the p-type material is more positive than the n-type material
the n-type material is more positive than the p-type material
both the n-type and p-type materials have the same potential
there is no potential on the n-type or p-type materials
the p-type material is more positive than the n-type material
When a diode is forward biased, the voltage across it
is directly proportional to the current
is inversely proportional to the current
is directly proportional to the source voltage
remains approximately the same
remains approximately the same
Why is heat produced in a diode?
due to current passing through the diode
due to voltage across the diode
due to the power rating of the diode
due to the PN junction of the diode
due to current passing through the diode
The arrow in the schematic symbol of a diode points to
the n-type material, which is called the anode
the n-type material, which is called the cathode
the p-type material, which is called the anode
the p-type material, which is called the cathode
the p-type material, which is called the anode
The diode schematic arrow points to the:
trivalent-doped material
positive axial lead
anode lead
cathode lead
cathode lead
When checking a diode, low resistance readings both ways indicate the diode is:
open
satisfactory
faulty
not the problem
faulty
In a diode schematic, the anode is represented by a(n):
triangle
vertical line
zig-zag line
element indicator
triangle
An IC regulator receives an overload; it will:
shut down
compensate for heat
provide more voltage
sample and adjust
shut down
With full-wave rectification, current through the load resistor must be:
in opposite directions
to the external load
from the reverse biased diode
in the same direction
in the same direction
A characteristic curve is the result of a current versus voltage plot of diode activity, which begins at the:
3rd quadrant
current plot
graph origin
voltage plot
graph origin
Rectifier output polarity depends upon:
cycles of input
capacitor polarity
half or full wave
diode installation
diode installation
If the frequency of the applied ac signal to a half-wave rectifier is 60 Hz, the frequency of the pulsating dc output will be
30 pps
60 pps
90 pps
120 pps
60 pps
Thermal shutdown occurs in an IC regulator if:
power dissipation is too high
internal temperature is too high
current through the device is too high
load resistance increases
internal temperature is too high
The conduction band is closest to the valence band in
semiconductors
conductors
insulators
The distance is the same for all of the above.
semiconductors
With a half-wave rectified voltage across the load resistor, load current flows for what part of a cycle?
0 degrees
90 degrees
180 degrees
360 degrees
180 degrees
Which of the following circuits would require the least amount of filtering?
A half-wave rectifier
A full-wave rectifier
A bridge rectifier
A full-wave rectifier and a bridge rectifier
A full-wave rectifier and a bridge rectifier
The voltage where current may start to flow in a reverse-biased pn junction is called the
breakdown voltage
barrier potential
forward voltage
biasing voltage
breakdown voltage
Providing a constant output regardless of ac input or load resistance changes is the function of a:
transformer
filter
regulator
rectifier
regulator
When a diode is destroyed it has infinite impedance. When damaged by heat it will probably:
short
conduct more
conduct less
open
short
The area at the junction of p-type and n-type materials that has lost its majority carriers is called the
barrier potential
depletion region
n region
p region
depletion region
DC power should be connected to forward bias a diode as follows:
– anode, + cathode
– cathode, – anode
+ anode, – cathode
+ cathode, + anode
+ anode, – cathode
At any given time in an intrinsic piece of semiconductor material at room temperature
electrons drift randomly
recombination occurs
holes are created
All of the above
All of the above
In a power supply diagram, which block indicates a pulsating dc output?
transformer
filter
rectifier
regulator
rectifier
List three diode packages:
clip package, DIP, small current package
DIP, small current package, large current package
small current package, large current package, and SIP
small current package, large current package, clip package
small current package, large current package, clip package
The mimicking of an open/closed switch by a diode allows alternating current to be:
rectified
regulated
controlled
attenuated
rectified
