1.Choose the below option in terms of ascending order of band gap energy
a)
b)
c)
d)
Diamond, Graphite, Silicon
Graphite, Silicon, Diamond
Silicon, Graphite, Diamond
Silicon, Diamond, Graphite
2. Carrier lifetime for holes and electrons in a semiconductor ranges from
a)
b)
c)
d)
Milliseconds to hundreds of nanoseconds
Microseconds to seconds
Nanoseconds to hundreds of microseconds
Nanoseconds to thousands of milliseconds
3. Choose the below option in terms of ascending order of band gap energy
a)
b)
c)
d)
Conduction and Diffusion
Conduction
Diffusion
None of the above
4. The thickness of space charge region for a P-N junction diode is of the order of
a)
b)
c)
d)
10-4 cm
10-2 cm
10 cm
100 cm
5. Formation of a junction between a sample of P-type and N-type material causes _______
action
a)
b)
c)
d)
Rectifying
Conducting
Insulating
None of the above
6. Cut-In or breakdown voltage of Silicon diode is greater than that of Germanium diode
because ______.
a)
b)
c)
d)
Reverse saturation current in a Silicon diode is lesser than that in Germanium diode
Reverse saturation current in Germanium diode is lesser than that in Silicon diode
The current is initially less dependent on voltage for a Silicon diode
None of the above
7.The d.c. resistance of a crystal diode is ………….. its a.c. resistance
a)
b)
c)
d)
The same as
More than
Less than
None of the above
8. A crystal diode is used as ……………
a)
b)
c)
d)
an amplifier
a rectifier
an oscillator
a voltage regulator
9. Question 9 Band gap Energy for Silicon and Germanium at Room Temperature (300°K) are
____ & ____ respectively
a)
b)
c)
d)
56eV, 1.1eV
72eV, 1.2eV
1eV, 0.72eV
1eV, 0.56eV
10. Depletion layer in semiconductor diode is caused by
a)
b)
c)
d)
Doping
Recombination
Barrier potential
Ions
11. Voltage multipliers produce
a) Low voltage and low current
b) Low voltage and high current
c) High voltage and low current
d) High voltage and high current
12. A Diode is a
a)
b)
c)
d)
Bilateral Device
Nonlinear Device
Linear Device
Unipolar Device
13. What is a Clamper?
a)
b)
c)
d)
A circuit that adds a DC voltage (positive or negative) to a wave
A circuit that adds a AC voltage (positive or negative) to a wave
A circuit that removes a part (positive or negative) of a waveform
All of the above
14. What is a Clipper?
a) circuit that adds a DC voltage (positive or negative) to a wave
b) A circuit that adds a AC voltage (positive or negative) to a wave
c) A circuit that removes a part (positive or negative) of a waveform
d) All of the above
15.The reverse saturation current in a Silicon Diode is _____ than that of Germanium Diode
a)
b)
c)
d)
Equal
Higher
Lower
Depends on temperature
16.The forward voltage drop across a silicon diode is about ……
a)
b)
c)
d)
2.5 V
3V
10 V
0.7 V
17. A zener diode has ………..
a)
b)
c)
d)
one pn junction
two pn junctions
three pn junctions
none of the above
18. A zener diode is used as …………….
a)
b)
c)
d)
an amplifier
a voltage regulator
a rectifier
a multivibrator
19. A zener diode is always ………… connected.
a)
b)
c)
d)
reverse
forward
either reverse or forward
none of the above
20.A zener diode utilizes ……….. characteristics for its operation.
a)
b)
c)
d)
forward
reverse
both forward and reverse
none of the above
21. A Zener diode has ………….. breakdown voltage.
a)
b)
c)
d)
undefined
sharp
zero
none of the above
22. A Zener diode is …………………. device
a)
b)
c)
d)
a non-linear
a linear
an amplifying
none of the above
23. ………. rectifier has the lowest forward resistance.
a)
b)
c)
d)
solid state
vacuum tube
gas tube
none of the above
24. A series resistance is connected in the zener circuit to………...
a)
b)
c)
d)
properly reverse bias the zener
protect the zener
properly forward bias the zener
none of the above
25. The ripple factor of a half-wave rectifier is …………………
a)
b)
c)
d)
2
1.21
2.5
0.4
26. The most widely used rectifier is ……………….
a)
b)
c)
d)
half-wave rectifier
centre-tap full-wave rectifier
bridge full-wave rectifier
none of the above
27. The maximum efficiency of a half-wave rectifier is ………………..
a) 40.6 %
b) 81.2 %
c) 50 %
d) 25 %
28. The number of holes in an intrinsic semiconductor is
a)
b)
c)
d)
Equal to number of free electrons
Greater than number of free electrons
Less than number of free electrons
None of the above
29. The conventional current in a PN junction diode flows:
a)
b)
c)
d)
From positive to negative
From negative to positive
In the direction opposite to the electron flow
Both (a) and (c)
30. When a diode is reverse biased, it is equivalent to
a) An OFF switch
b) an ON switch
c) A high resistance
d) none of the above
31. The resistance of a diode is equal to
a) Ohmic resistance of the P- and N- semiconductors
b) Junction resistance
c) Reverse resistance
d) Algebraic sum of (a) and (b) above
32. When forward biased, a diode
a) Blocks current
b) conducts current
c) Has a high resistance
d) drops a large voltage.
33. Junction breakdown of a PN junction occurs
a) With forward bias
b) with reverse bias
c) Because of manufacturing defect
d) None of these
34. Reverse saturation current in a silicon PN junction diode nearly doubles for every
a) 2° C rise in temperature
b) 5° C rise in temperature
c) 6° C rise in temperature
d) 10° C rise in temperature
35. The diode D is an ideal in the circuit shown in Fig below. The current, I will be
a) – 2nA
b) zero
c) 2 mA
d) 4mA
36.The voltage at Vl and V2 of the arrangement shown in Fig. below will be respectively
a) 6V and 5.4V
b) 5·4Vand 6V
c) 3V and 5·4V
d) 6V and 5V
37. A 5 V reference is drawn from the circuit shown in Fig below if the zener diode current
is of 5mA, then R will be
a) 50 Ω
b) 500 Ω
c) 5000 Ω
d) 50,000 Ω
38. In any atom, the potential energy of an orbiting electron is
a) always positive
b) always negative
c) sometime positive, sometime negative
d) numerically less than its kinetic energy
39. Regarding valence band in a solid which statement is false?
a) it represents the energy possessed by the valence electrons
b) it is the highest occupied band
c) it may be empty in some solids
d) it is either completely filled or partially filled
40. The neighbouring atoms in the crystalline lattice structure of a semiconductor like Ge form
............................................... bonds.
a) ionic
b) covalent
c) metallic
d) molecular
41. In order to obtain a p-type germanium, the germanium should be doped with a
a) trivalent impurity
b) tetravalent impurity
c) pentavalent impurity
d) any of the above will do
42. For converting intrinsic semiconductor into N-type extrinsic semiconductor, which of the
following doping elements would not be suitable?
a) arsenic
b) antimony
c) indium
d) phosphorous
43. Consider the energy level diagram of an intrinsic semiconductor. The Fermi level lies in
the
a) valence band
b) forbidden gap
c) conduction band or
d) it can be at any of the above locations depending upon the doping concentration and
temperature
44. At higher forward voltages, a junction diode is likely to
a) burn out
b) get saturated
c) suffer breakdown
d) become noisy
45. A general purpose diode is more likely to suffer avalanche breakdown rather than Zener
breakdown because
a) its leakage current is small
b) it has strong covalent bands
c) it is lightly-doped
d) it has low reverse resistance
46. The static V/I characteristics of a junction diode can be described by the equation called
a) Richardson-Dushman equation
b) Boltzmann diode equation
c) Einstein's photoelectic equation
d) Child's three half-power law
47. The turn-on voltage of a Ge junction diode is ___ volt.
a) 0.7
b) 0.3
c) 1
d) 0.1
48. For converting intrinsic semiconductors into extrinsic ones, the level of doping required is
about
a) 1 : 103
b) 1 : 105
c) 1 : 108
d) 0.111805556
49. At 0K, a pure semiconductor behaves like an insulator because
a) drift velocity of free electrons is very small
b) energy possessed by electrons at that low temperature is almost zero
c) there is no recombination of electrons with holes
d) no free electrons are available for current conduction
50. The temperature coefficient of an intrinsic semiconductor is
a) positive
b) negative
c) zero
d) like that of metals
51. Barrier potential in a P-N junction is caused by
a) thermally-generated electrons and holes
b) diffusion of majority carriers across the junction
c) migration of minority carriers across the junction
d) flow of drift current
52. The forward region of a semiconductor diode characteristic curve is where diode appears
as
a)
b)
c)
d)
a constant-current source
a capacitor
an OFF switch
an ON switch
53. The peak inverse voltage (PIV) is applied across a diode when it is
a) ON
b) on a heat sink
c) reverse-biased
d) forward-biased
54. When biased correctly, a Zener diode
a) acts as a fixed resistance
b) has a constant voltage across it
c) has a constant current passing through it
d) never overheats
55. A light-emitting diode can be made from
a) phosphorescent material
b) germanium
c) silicon
d) gallium arsenide
56. For converting a piece of pure silicon into a P-type extrinsic semiconductor, you will add
an extremely small quantity of
a) antimony
b) phosphorous
c) arsenic
d) boron
57. The maximum reverse voltage that can be applied to an ordinary semiconductor diode
without irreversible damage is called
a) peak inverse voltage
b) Zener voltage
c) avalanche breakdown voltage
d) cut-off voltage
58. Addition of impurity in the ratio of 1 in 108 to a pure or intrinsic semiconductor
a) decreases its conductivity nearly 100 times
b) increases its conductivity nearly 108 times
c) increases its conductivity nearly 100 times
d) increases its resistivity nearly 100 times
59. In a P-type semiconductor, free electrons
a) form majority carriers
b) take no part in conduction
c) equal the number of holes
d) form minority carriers
60. A tunnel diode
a) has a small tunnel in its junction
b) is a point contact diode with a high reverse resistance
c) is a gallium arsenide device
d) is a highly-doped P-N junction device
61. What circuit activity may shift a characteristic curve so that diode operating points are
different?
a)
b)
c)
d)
higher power (heat)
higher resistance
lower voltage
lower current
62. What is wrong with this diode?
a)
b)
c)
d)
open
short
nothing
not enough data
63. The dc current through each diode in a bridge rectifier equals:
a)
b)
c)
d)
the load current
half the dc load current
twice the dc load current
one-fourth the dc load current
64. When matching polarity connections have been made and the potential difference (PD) is
above 0.7 V, the diode is considered to be:
A.
B.
C.
D.
not working
forward biased
reverse biased
an open switch
65. In a power supply diagram, which block indicates a smooth dc output?
a.
b.
c.
d.
transformer
filter
rectifier
regulator
66. What is the current through the LED?
a.
b.
c.
d.
0 mA
23 mA
18 mA
13 mA
67.Since diodes are destroyed by excessive current, circuits must have:
a) higher voltage sources
b) current limiting resistors
c) more dopants
d) higher current sources
68. A diode for which you can change the reverse bias, and thus vary the capacitance is
called a
a.
b.
c.
d.
varactor diode
tunnel diode
zener diode
switching diode
69. What is the current through the diode?
a.
b.
c.
d.
1 mA
0.975 mA
0.942 mA
0.0 mA
70. What is the current through the zener diode?
a.
b.
c.
d.
0 mA
7 mA
8.3 mA
13 mA
71. Why is heat produced in a diode?
a.
b.
c.
d.
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
72. What is the peak output voltage for this half-wave rectifier?
a.
b.
c.
d.
1V
7.8V
10.9V
15.6V
73. What is wrong with this circuit?
a.
b.
c.
d.
The zener is open.
The zener is shorted.
nothing
not enough data
74. Use the information provided here to determine the value of IDQ.
a. 0 mA
b. 4.3 mA
c. 5 mA
d. 10 mA
75. Determine the current level if E = 15 V and R = 3 kΩ.
a. 0 A
b. 4.76 mA
c. 5 mA
d. 5 A
76. Determine the voltage across the resistor.
a. 0 V
b. 0.09 V
c. 0.2 V
d. 0.44 V
77. Determine the value of the load resistor.
a. RL = 5 kΩ
b. RL = 5.5 kΩ
c. RL = 6 kΩ
d. None of the above
78. Determine ID.
a) 0 mA
b) 1.893 mA
c) 2.036 mA
d) 2.143 mA
79. Determine V2.
a. 3.201 V
b. 0 V
c. 4.3 V
d. 1.371 V
80. Determine ID2.
a. 29.40 mA
b. 30.30 mA
c. 14.70 mA
d. None of the above
81. Determine ID1.
a. 0 mA
b. 29.40 mA
c. 14.70 mA
d. 14.09 mA
82. Determine ID2.
a. 6.061 mA
b. 0.7 mA
c. 3.393 mA
d. 3.571 mA
83. Determine the current through each diode if E1 = E2 = 0 V.
a. 4.65 mA
b. 9.3 mA
c. 18.6 mA
d. 0.7 mA
84. Determine Vo if E1 = E2 = 10 V.
a. 9.3 V
b. 10 V
c. –10 V
d. 0 V
85. What best describes the circuit?
a. Full-wave rectifier
b. Half-wave rectifier
c. Clipper
d. Clamper
86. Determine the peak value of the current through the load resistor.
a. 2.325 mA
b. 5 mA
c. 1.25 mA
d. 0 mA
87. Determine the average value of the current through the load resistor.
a. 2.5 mA
b. 0 mA
c. 1.37 mA
d. 1.479 mA
88. What best describes the circuit?
a. Full-wave rectifier
b. Half-wave rectifier
c. Clipper
d. Clamper
89. Determine the peak value of the output waveform
a. 25 V
b. 15 V
c. –25 V
d. –15 V
90. Determine the peak for both half cycles of the output waveform.
a. 16 V, –4 V
b. 16 V, 4 V
c. –16 V, 4 V
d. –16 V, –4 V
91. What best describes the circuit?
a. Full-wave rectifier
b. Half-wave rectifier
c. Clipper
d. Clamper
92. Calculate IL and IZ.
a. 2 mA, 0 mA
b. 4 mA, 2 mA
c. 2 mA, 2 mA
d. 2 mA, 4 mA
93. With this Zener diode in its “on state,” what is the level of IZ for the maximum load
resistance?
a. 0 mA
b. Undefined
c. Equal to IRL
d. IZM
94. What is the voltage measured from the negative terminal of C4 to the negative terminal of
the transformer?
i. –10 V
ii. –20 V
iii. 10 V
iv. 20 V
95. The intersection of the load line with the characteristic curve determines the _______ of
the system.
a. point of operation
b. load-line analysis
c. characteristic curve
d. forward bias
96. The slope of the load line depends on the _______.
a. type of the diode used
b. characteristic curve
c. load resistor
d. source voltage
97. The load line is defined by the _______ and a characteristic curve is defined by the
_______.
a) quiescent point, device
b) device, network
c) network, device
d) None of the above
98.The quiescent point (Q-point) is defined by a(n) _______.
a. ac network
b. dc network
c. ac and dc network
d. None of the above
99. A germanium diode is approximated by _______ equivalent for voltages less than 0.3 V.
a. a short circuit
b. a series circuit
c. a parallel circuit
d. an open circuit
100. The PIV rating of the diodes in a full-wave rectifier must be larger than _______ Vm.
a. 0.318
b. 0.636
c. 2
d. 1