Exam
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1)
Doping is used to ________.
1)
A)
decrease the conductivity of an intrinsic semiconductor
B)
increase the insulative quality of an intrinsic semiconductor
C)
stabilize the conductivity of an intrinsic semiconductor
D)
increase the conductivity of an intrinsic semiconductor
Answer:
D
A)
B)
C)
D)
2)
When a p–n junction’s depletion layer is narrowed and the device acts as a nearly perfect
conductor, it is ________.
2)
A)
reverse–biased
B)
unbiased
C)
forward–biased
D)
None of the above
Answer:
C
A)
B)
C)
D)
3)
An advantage of the miniaturization of electronic devices is that they ________.
3)
A)
reduce cost
B)
increase availability
C)
improve reliability
D)
increase speed
Answer:
D
A)
B)
C)
D)
4)
The ideal diode symbol has an arrow that points in the direction of ________.
4)
A)
positive terminal under forward bias
B)
the forward current flow
C)
the leakage current flow
D)
All of the above
Answer:
B
A)
B)
C)
D)
1
5)
The nominal voltage for a 1N961 Fairchild 10–V Zener diode has a temperature coefficient of 0.072.
If the temperature increases by 50° C, what is the change in V?
5)
A)
0.108 V
B)
0.36 V
C)
0.54 V
D)
0.72 V
Answer:
B
A)
B)
C)
D)
6)
The DC or the static resistance of the diode is given by ________.
6)
A)
RD=VVD
VID
B)
RD=VD1–VD2
ID1–ID2
C)
RD=VD
ID
D)
All of the above can be used.
Answer:
C
A)
B)
C)
D)
7)
The term ________ is applied to any material that supports a generous flow of charge when a
voltage source of limited magnitude is applied across its terminals.
7)
A)
semiconductor
B)
conductor
C)
insulator
D)
dielectric
Answer:
B
A)
B)
C)
D)
8)
The diode electrode with n–type material is called the ________.
8)
A)
depletion region
B)
anode
C)
Zener region
D)
cathode
Answer:
D
A)
B)
C)
D)
9)
When tested with an ohmmeter, a diode should have a relatively small resistance for ________
condition.
9)
A)
zero–biased
B)
both reverse– and forward–biased
C)
the reverse–biased
D)
the forward–biased
Answer:
D
A)
B)
C)
D)
2
10)
The characteristics of an ideal diode are those of a switch that can conduct current in ________.
10)
A)
both directions
B)
the reverse bias direction
C)
only one direction
D)
None of the above
Answer:
C
A)
B)
C)
D)
11)
The diffusion capacitance of a diode is a shunt capacitance effect that occurs when the diode
________.
11)
A)
is large
B)
is forward biased
C)
is reverse biased
D)
is small
Answer:
B
A)
B)
C)
D)
12)
An LED produces visible or invisible light when ________.
12)
A)
the electrons and the holes combine with each other
B)
a hole enters the diffusion region
C)
an electron enters the diffusion region
D)
the electrons and the holes combine in the diffusion region
Answer:
A
A)
B)
C)
D)
13)
Light–emitting diodes emit light when the p–n junction is ________.
13)
A)
zero biased
B)
forward–biased
C)
operating in the Zener region
D)
reverse–biased
Answer:
B
A)
B)
C)
D)
14)
The isolated atomic energy structure associated with electron orbital shells is called a/an ________.
14)
A)
energy gap
B)
energy band
C)
conduction band
D)
valence band
Answer:
B
A)
B)
C)
D)
3
15)
One electron volt is equal to ________ Joules.
15)
A)
3.6 ×10–16
B)
0.7 ×10–16
C)
1.6 ×10–19
D)
It depends on which shell the electron is in
Answer:
C
A)
B)
C)
D)
16)
The term ________ is applied to a material that has a conductivity level somewhere between the
extremes of conductivity.
16)
A)
semiconductor
B)
conductor
C)
insulator
D)
ionic
Answer:
A
A)
B)
C)
D)
17)
Suppose that a particular Zener diode has a temperature coefficient of 0.00575. If the temperature
of this Zener diode increases by 50° C, what is the change in Vz?
17)
A)
5 × 0.00575 = 0.02875
B)
50 × 0.00575 = 0.2875
C)
10 × 0.00575 = 0.0575
D)
Cannot tell without looking at the circuit in which the Zener is used
Answer:
B
A)
B)
C)
D)
18)
Silicon diodes have been more significantly developed than germanium because ________.
18)
A)
it has a lower forward voltage drop
B)
it is cheaper
C)
it is more tolerant of heat
D)
it is easier to produce
Answer:
B
A)
B)
C)
D)
19)
The act of giving off light by applying an electrical source of energy is called ________.
19)
A)
photons
B)
electroluminescence
C)
light power
D)
laser
Answer:
B
A)
B)
C)
D)
4
20)
A p–n junction is reverse biased when ________.
20)
A)
the applied potential causes the n–type material to be more positive than the p–type material
B)
the current flow across the junction is based on minority carrier transfer
C)
the applied potential causes the p–type material to be more negative than the n–type material
D)
All of the above
Answer:
D
A)
B)
C)
D)
21)
The direction of the arrow in the diode symbol points in the direction of ________.
21)
A)
positive terminal under forward bias
B)
from p–type of semiconductor to n–type semiconductor material
C)
from n–type of semiconductor to p–type semiconductor material
D)
leakage current flow
Answer:
B
A)
B)
C)
D)
22)
Which material(s) are commonly used in high–speed applications?
22)
A)
Si exclusively
B)
Si and Ge
C)
GaAs and Ge
D)
GaAs and Si
Answer:
C
A)
B)
C)
D)
23)
The reverse saturation current of a diode will just about ________ for every 10°C rise in the diode
temperature.
23)
A)
decrease proportionately with temperature
B)
increase proportionately with temperature
C)
double
D)
half
Answer:
C
A)
B)
C)
D)
24)
Pentavalent atoms are often referred to as ________.
24)
A)
donor atoms
B)
majority carriers
C)
minority carriers
D)
acceptor atoms
Answer:
A
A)
B)
C)
D)
5
25)
When silicon is doped with either a pentavalent or a trivalent impurity its resistance will ________.
25)
A)
make the resistance stable against variation due to temperature
B)
decrease
C)
increase
D)
None of the above
Answer:
B
A)
B)
C)
D)
26)
The term ________ is applied to a material that offers a very low level of conductivity under
pressure from an applied voltage.
26)
A)
conductor
B)
insulator
C)
ionic
D)
semiconductor
Answer:
B
A)
B)
C)
D)
27)
The maximum reverse bias potential that can be applied to a Zener diode before it enters the Zener
region is called the ________.
27)
A)
barrier voltage
B)
depletion voltage
C)
PIV
D)
threshold voltage
Answer:
C
A)
B)
C)
D)
28)
An LED light is expected to last for ________.
28)
A)
2,000 hours
B)
10,000 hours
C)
25,000 hours
D)
5,000 hours
Answer:
C
A)
B)
C)
D)
29)
In a p–type material, the minority carriers are ________.
29)
A)
conduction–band electrons
B)
valence–band holes
C)
conduction–band electrons
D)
valence–band electrons
Answer:
A
A)
B)
C)
D)
6
30)
When a p–n junction is reverse–biased, its junction resistance is ________.
30)
A)
constantly changing
B)
determined by the components that are external to the device
C)
high
D)
low
Answer:
C
A)
B)
C)
D)
31)
When pentavalent elements are used in doping, the resulting material is called ________ material
and has an excess of ________.
31)
A)
p–type; valence–band holes
B)
p–type; conduction–band electrons
C)
n–type; conduction–band electrons
D)
n–type; valence–band holes
Answer:
C
A)
B)
C)
D)
32)
The transition capacitance of a diode is a shunt capacitive effect that occurs when the diode
________.
32)
A)
is small
B)
is reverse–biased
C)
is forward–biased
D)
is large
Answer:
B
A)
B)
C)
D)
33)
When tested with an ohmmeter, a diode should have a relatively high resistance for ________
condition.
33)
A)
both reverse and forward–biased
B)
zero–biased
C)
the forward–biased
D)
the reverse–biased
Answer:
D
A)
B)
C)
D)
34)
The piecewise linear model, equivalent circuit of the diode consists of ________.
34)
A)
a battery, a small resistor, and the ideal diode
B)
a junction capacitor, a battery, a small resistor, and the ideal diode
C)
a battery and the ideal diode
D)
the ideal diode
Answer:
A
A)
B)
C)
D)
7
35)
Reverse saturation current is nomrally larger than in Shockley’s equation. This is due to
35)
A)
junction area
B)
higher doping levels
C)
leakage current
D)
temperature sensitivity
E)
all of the above
Answer:
E
A)
B)
C)
D)
E)
36)
A p–n junction is forward biased when ________.
36)
A)
the applied potential causes the n–type material to be more positive than the p–type material
B)
the applied potential causes the n–type material to be more negative than the p–type material
C)
both materials are at the same potential
D)
None of these
Answer:
B
A)
B)
C)
D)
37)
When a p–n junction is reverse–biased, the depletion layer is ________ and the device acts as a
near–perfect ________.
37)
A)
narrowed; insulator
B)
narrowed; conductor
C)
widened; conductor
D)
widened; insulator
Answer:
D
A)
B)
C)
D)
38)
To make a p–type of semiconductor material you need a doping material that is ________.
38)
A)
tetravalent
B)
pentavalent
C)
trivalent
D)
hexavalent
Answer:
C
A)
B)
C)
D)
39)
As semiconductor devices have become ________ one of the primary purposes of the container is
simply to provide a means for physical handling.
39)
A)
widely used
B)
larger
C)
miniaturized
D)
more powerful
Answer:
C
A)
B)
C)
D)
8
40)
When trivalent elements are used in doping, the resulting material is called ________ material and
has an excess of ________.
40)
A)
p–type; conduction–band electrons
B)
n–type; valence–band holes
C)
n–type; conduction–band electrons
D)
p–type; valence–band holes
Answer:
D
A)
B)
C)
D)
41)
The diode electrode with p–type material is called the ________.
41)
A)
cathode
B)
depletion region
C)
Zener region
D)
anode
Answer:
D
A)
B)
C)
D)
42)
As the device temperature increases, semiconductor materials tend to have ________.
42)
A)
relatively unchanged conduction conduction levels
B)
an increasing number of free electrons
C)
lower conduction levels
D)
a decreasing number of free electrons
Answer:
B
A)
B)
C)
D)
43)
The energy required to move an electron in silicon from the valence band to the conduction band is
________.
43)
A)
10 eV
B)
1.1 eV
C)
0.67 eV
D)
1.8 eV
Answer:
B
A)
B)
C)
D)
44)
In an n–type material, the majority carriers are ________.
44)
A)
valence–band electron
B)
conduction–band electrons
C)
conduction–band holes
D)
valence–band holes
Answer:
B
A)
B)
C)
D)
9
45)
In the Zener region the current ________ and the voltage across the diode ________.
45)
A)
is almost constant; can increase a lot
B)
is almost constant; is almost constant
C)
can increase a lot; can increase a lot
D)
can increase a lot; is almost constant
Answer:
D
A)
B)
C)
D)
46)
The characteristic of an ideal diode are those of a switch that can conduct current ________.
46)
A)
in one direction only
B)
in both directions but in only one direction at a time
C)
in both directions
D)
depends on the circuit it is used in
Answer:
A
A)
B)
C)
D)
47)
The ________ diode is a short circuit for the region of conduction and it is an open circuit in the
region of nonconduction.
47)
A)
typical
B)
small–signal
C)
ideal
D)
power
Answer:
C
A)
B)
C)
D)
48)
The typical range of the ac resistance of a diode in the active region is ________.
48)
A)
1 to 10
B)
50 to 100
C)
100 to 500
D)
1 to 100
Answer:
D
A)
B)
C)
D)
49)
Pentavalent elements have ________ valence electrons.
49)
A)
1
B)
5
C)
4
D)
3
Answer:
B
A)
B)
C)
D)
10
50)
Increasing the temperature of a forward–biased diode ________.
50)
A)
causes forward current to increase
B)
has no significant effect effect on the forward current
C)
causes forward current to decrease
D)
None of these
Answer:
A
A)
B)
C)
D)
51)
Which of the following is not a commonly used semiconductor material’?
51)
A)
silicon
B)
carbon
C)
germaniun
D)
lead
Answer:
D
A)
B)
C)
D)
52)
Some of the modern ohmmeters have a diode test setting. If you do not have one of these
ohmmeters then to test the diode you need to check its resistance in the forward and the reverse
direction. These resistances should be ________.
52)
A)
relatively high in the forward direction and relatively low in the reverse direction
B)
relatively high in the forward direction and relatively high in the reverse direction
C)
relatively low in the forward direction and relatively low in the reverse direction
D)
relatively low in the forward direction and relatively high in the reverse direction
Answer:
D
A)
B)
C)
D)
TRUE/FALSE. Write ‘T’ if the statement is true and ‘F’ if the statement is false.
53)
A normalized value has a reference magnitude of one.
53)
Answer:
True
False
54)
Holes are the majority carriers in a p–type material.
54)
Answer:
True
False
55)
A free electron has a higher energy state than any that are bound to their nucleus.
55)
Answer:
True
False
56)
An intrinsic semiconductor is one that is as pure as present–day technology can make it.
56)
Answer:
True
False
11
57)
The reverse breakdown voltage of an LED is typically less than 12 V.
57)
Answer:
True
False
58)
The amount of photon energy emitted at the p–n junction of a silicon diode is negligible.
58)
Answer:
True
False
59)
Electrons are the minority carriers in an n–type material.
59)
Answer:
True
False
60)
The amount of energy that is converted to heat at a silicon p–n junction can be a significant design
consideration.
60)
Answer:
True
False
61)
The quantum–Volt (qV) is the unit of measurement for electron energy.
61)
Answer:
True
False
62)
Si and Ge both have negative temperature coefficients.
62)
Answer:
True
False
12
Answer Key
Testname: C1
1)
D
2)
C
3)
D
4)
B
5)
B
6)
C
7)
B
8)
D
9)
D
10)
C
11)
B
12)
A
13)
B
14)
B
15)
C
16)
A
17)
B
18)
B
19)
B
20)
D
21)
B
22)
C
23)
C
24)
A
25)
B
26)
B
27)
C
28)
C
29)
A
30)
C
31)
C
32)
B
33)
D
34)
A
35)
E
36)
B
37)
D
38)
C
39)
C
40)
D
41)
D
42)
B
43)
B
44)
B
45)
D
46)
A
47)
C
48)
D
49)
B
50)
A
Answer Key
Testname: C1
51)
D
52)
D
53)
TRUE
54)
TRUE
55)
TRUE
56)
TRUE
57)
TRUE
58)
TRUE
59)
FALSE
60)
TRUE
61)
FALSE
62)
TRUE