Semiconductor Electronics: Materials, Devices And Simple Circuits Questions

We provide semiconductor electronics: materials, devices and simple circuits practice exercises, instructions, and a learning material that allows learners to study outside of the classroom. We focus on semiconductor electronics: materials, devices and simple circuits skills mastery so, below you will get all questions that are also asking in the competition exam beside that classroom.

List of semiconductor electronics: materials, devices and simple circuits Questions

Question No Questions Class
1 Photodiode is a device
A. Which is always operated in reverse bias
B. Which is always operated in forward bias
C. In which photo current is independent of intensity of incident radiation
D. Which may be operated in forward or reverse bias
12
2 A semiconductor ( X ) is made by doping a germanium crystal with arsenic ( (mathrm{Z}= )
33). A second semiconductor Y is made
by doping germanium with indium ( (z= )
49). The two are joined end to end and
connected to a battery as shown. Which
of the following statements is correct?
A. ( x ) is ( p ) -type, ( Y ) is ( n ) -type and the junction is forward biased
B. ( x ) is ( n ) -type, ( Y ) is ( p ) -type and the junction is forward biased
c. ( x ) is ( p ) -type, ( Y ) is ( n ) -type and the junction is reverse biased
D. ( x ) is ( n ) -type, ( Y ) is ( p ) -type and the junction is reverse biased
12
3 7. Barrier potential of a p-n junction diode does not depend
on
(a) Diode design
(c) Forward-biased
(b) Temperature
(d) Doping density
12
4 A full-wave rectifier circuit along with
the output is shown. The contribution(s)
from the diode 1 is (are).
A.
B. A, C
( c . B, D )
D. ( A, B, C, D )
12
5 For an amplitude modulated wave, the maximum amplitude is found to be 10 while the minimum amplitude is found
to be ( 2 v ). Determine the modulation
index ( mu )
12
6 Ge and Si diodes start conducting at 0.3
V and 0.7 V respectively. In the following figure if Ge diode connection are
reversed, the value of ( V_{o} ) changes by :
(assume that the Ge diode has large
breakdown voltage)
A . ( 0.6 v )
B. 0.8
( c cdot 0.4 v )
( D, 0.2 mathrm{v} )
12
7 The current gain of a transistor in a
Common base arrangement is ( 0.98 . ) The Change in collector current
corresponding to a change of ( 5 m A ) in emitter current is :
( mathbf{A} cdot 0.1 m A )
B. ( 0.2 m A )
c. ( 4.9 m A )
D. ( 9.2 m A )
12
8 23. In an NPN transistor, the collector current is 24 mA. If
80% of electrons reach collector, its base current in mA is
(a) 36
(b) 26
(c) 16
(d) 6
12
9 20. The forward-biased diode connection is
(a) 2 Dwwav (b) 2 Dww*2 v
(c) *2 Vww-2v (d) -3Dww-3 v
(JEE Main 2014)
12
10 The binary number of decimal number
( (9.25)_{10} ) is
A . 1101.01
в. 1001.01
c. 1001.10
D. 1110.010
12
11 A full-wave p-n diode rectifier uses a load resistor of ( 1500 Omega ). No filter is used.
The forward bias resistance of the diode
is ( 10 Omega . ) the efficiency of the rectifier is
A . ( 81.2 % )
B . ( 40.6 % )
c. ( 80.4 % )
D. ( 40.2 % )
12
12 The truth-table given below is for which gate?
( begin{array}{lll}A & B & C \ 0 & 0 & 1 \ 0 & 1 & 1 \ 1 & 0 & 1 \ 1 & 1 & 0end{array} )
A. xor
B. OR
c. AND
D. NAND
12
13 The ratio (R) of output resistance ( r_{0} )
and and the input resistance ( r_{i} ) in
measurements of input and output
characteristics of a transistor is
typically in the range:
A . ( R sim 10^{2}-10^{3} )
В. ( R sim 1-10 )
c. ( R sim 0.1-1.0 )
D. ( R sim 0.1-0.01 )
12
14 represents
45. Symbol
(a) NAND gate
(c) NOT gate
(b) NOR gate
(d) XNOR gate
12
15 Write the truth table of logic OR gate. 12
16 The maximum frequency of operation of photodiodes is of the order of:
( mathbf{A} cdot 1 k H z )
в. ( 1 M H z )
c. ( 1 G H z )
D. ( 1 T H z )
12
17 With rise in temperature, resistance of
a semiconductor material (germanium or silicon)
A . increases
B. decreases
c. remains the same
D. first increases then decreases
12
18 The number of silicon atomes per ( m^{3} ) is
( 5 times 10^{28} . ) This is doped simultaneously
with ( 5 times 10^{28} ) atoms per ( m^{3} ) of Arsenic
and ( 5 times 10^{20} ) per ( m^{3} ) atoms of Indium.
Calculate the number of electrons and
holes. Given that ( n_{1}=1.5 times 10^{16} m^{-3} )
Is the material ( n ) -type or ( p- ) type?
12
19 To get an output ( Y=1 ) in given circuit
which of the following input will be
correct.
( mathbf{A} cdot A=1 ; B=0 ; C=1 )
В. ( A=1 ; B=1 ; C=0 )
c. ( A=0 ; B=1 ; C=0 )
D. ( A=1 ; B=0 ; C=0 )
12
20 State whether given statement is True or False
Doping of pure ( S i ) with trivalent impurities, gives p-type semiconductors
A. True
B. False
12
21 In p-type semiconductors, holes are:
A. majority carriers
B. minority carriers
( c . ) absent
D. none of the above
12
22 The minimum number of gates required to realise the expression ( Z= ) ( D A B C+D overline{A B C} ) is
A. One
B. Two
c. Eight
D. Five
12
23 For a transistor, ( beta=100 . ) The value of ( alpha )
is
A . 1.01
B. 0.99
( c cdot 100 )
D. 0.01
12
24 If electromagnetic rays are incident on
a semiconductors its conductivity.
A. Increases
B. Increases with increases frequency
C. Increases when frequency increases above certain frequency
D. Increases when wavelength is increases above a certain wavelength
12
25 A semiconductor is doped with a donor
impurity then [more than one option may be correct
This question has multiple correct options
A. the hole concentration increases
B. the hole concentration decreases the electron
concentration increases
C. the electron concentration increases
D. the electron concentration decreases
12
26 The potential in the depletion layer is
due to:
A. electrons
B. holes
( c . ) ions
D. forbidden band
12
27 In an LED, the longer lead is always
connected to the terminal
of the battery and the shorter lead is
connected to the
terminal of the cell (or battery)
A. positive, negative
B. negative, positive
c. positive, neutral
D. neutral, positive
12
28 Which of the following statement(s)
is/are true about holes?
A. They flow from positive terminal to negative terminal
B. They flow from negative terminal to positive terminal
C. They do not flow
D. None of these
12
29 When PNjunction os forward biased the current in junction
A. increases
B. decreases
c. Remains same
D. None of these
12
30 How does a diode acts as a rectifier. 12
31 Mention practical importance of Zener
diode in a laboratory.
12
32 ( ln a p-n-p ) transistor the base is the
n-region. Its width relative to the ( p ) regions is
A. smaller
B. larger
c. same
D. not related
12
33 The conduction band and valency band of a good conductor are
A. well separated.
B. just touch.
c. very close.
D. overlapped.
12
34 Suppose a pure ( boldsymbol{S} boldsymbol{i} ) crystal has ( boldsymbol{5} times )
( 10^{28} ) atoms ( m^{-3} . ) It is doped by 1 ppm
concentration of pentavalent ( boldsymbol{A} boldsymbol{s} )

Calculate the number of electrons and
holes. Given that ( n_{i}=1.5 times 10^{16} m^{-3} )

12
35 In which bias can a zener diode be used
as voltage regulator?
12
36 In a Zener diode regulated power supply, unregulated DC input of ( 10 V ) is
applied. If the resistance ( left(R_{s}right) ) connected
in series with a Zener diode is ( 200 Omega )
and the Zener voltage ( V_{z}=5 V ), the
current across the resistance ( boldsymbol{R}_{s} ) is:
( mathbf{A} cdot 15 m A )
B. ( 10 mathrm{mA} )
c. ( 20 m A )
D. ( 5 m A )
E . ( 25 m A )
12
37 In the circuit shown, assume the diode
to be ideal. When ( V_{i} ) increases from ( 2 V )
to ( 6 V ), the change in the current is (in
( boldsymbol{m} boldsymbol{A}) )
A . zero
B . 20
( c cdot 80 / 3 )
D. 40
12
38 What is an intrinsic semi conductor?
Give two examples.
12
39 What is a Fermi energy level? What is its position in case of an intrinsic semiconductor? 12
40 Draw the circuit diagram of AND gate using diodes. 12
41 In which of the following statements, the obtained impure semiconductor is of p-type?
A. Germanium is doped with bismuth
B. Silicon is doped with antimony
c. Germanium is doped with gallium
D. Silicon is doped with phosphorus
12
42 55. In order to obtain an output Y = 1 from the circuit of the
figure, the inputs must be
Во
A
(a) 0
(b) 1
(c) 1
(d) 1
B
1
0
0
1
C
0
0
1
0
12
43 The barrier potential in a p-njunction is ( 0.3 V . ) The current required is ( 6 m A . ) The
emf of the cell required for use in the circuit if a resistance of ( 200 Omega ) is
connected in series with junction is (in volt)
12
44 Energy band gap between valence band and conduction band for insulator is:
A. Zero
B. greater than 9 eV
c. less than conductors
D. approximately ( 1 e V )
12
45 The circuit is equivalent to
A. NOR gate
B. AND gate
c. NAND gate
D. or gate
12
46 The voltage gain of an amplifier with 9 negative feedback is ( 10 . ) The voltage gain without feedback will be
A . 90
B. 100
c. 10
D. 1.25
12
47 The circuit has two oppositively
connected ideal diodes in parallel. What
is the current flowing in the circuit?
( mathbf{A} cdot 1.71 A )
B . ( 2.00 A )
c. ( 2.31 A )
D. ( 1.33 A )
12
48 Reverse bias applied to a p-njunction
diode
A. Lowers the potential barrier
B. Decreases the majority charge carriers
C. Raises the potential barrier
D. Change the mass of ( p ) -n junction diode
12
49 The energy band gap (distance between the conduction band and valence band) in conductor is.
( mathbf{A} cdot mathbf{0} )
в. 4 А
( c cdot 10^{circ} )
( mathbf{D} cdot_{100 A}_{A}^{circ} )
12
50 Draw the circuit diagram of a full wave rectifier using two p-njunction diodes and explain its working. Show the input
and output waveforms.
12
51 Construct the logic symbol, Boolean expression and truth table for an AND
gate.
12
52 If the load resistance decreases in a
zener regulator, the zener current
A. Decreases
B. Stays the same
c. Increases
D. Equals the source voltage divided by the series resistance
12
53 Name the device used to make a circuit
function, only when needed?
12
54 Make logic symbol and write Boolean expression of NOT gate. 12
55 When an input signal 1 is applied to a NOT gate, its output is
( mathbf{A} cdot mathbf{1} )
B. 0
c. either 0 or 1
D. both 0 and 1
12
56 In ( n ) -p-n transistor, the arrow head on emitter represents that the conventional current flows from
A. base to emitter.
B. emitter to base
c. emitter to collector.
D. base to collector.
12
57 In the energy band diagram of a
material shown below, the open circles and filled circles denote holes and
electrons respectively. The material is:
A. an n-type semiconductor
B. a p-type semiconductor
( c . ) an insulator
D. a meta
12
58 The transistor are usually made of
A. metal oxides with high temperature coefficient of resistivity.
B. metals with high temperature coefficient of resistivity.
C. metals with low temperature coefficient of resistivity.
D. semiconducting materials having low temperature coefficient of resistivity.
12
59 In a p-njunction having depletion layer
of thickness ( 10^{-6} m ), the potential
across it is ( 0.1 mathrm{V} ). The electric field is
A ( cdot 10^{7} V / m )
В ( cdot 10^{-6} V / m )
c. ( 10^{5} V / m )
D. ( 10^{-5} V / m )
12
60 In p-type semiconductor, conduction is
due to
A. greater number of holes and less number of electrons.
B. only electrons.
C . only holes.
D. greater number of electrons and less number of holes.
12
61 At absolute zero, Si acts as
A. non-metal
B. metal
c. insulator
D. semiconductor
12
62 The output ( (X) ) of the logic circuit shown
in the figure will be
( mathbf{A} cdot X=bar{A} . bar{B} )
В . ( X=overline{A . B} )
( mathbf{c} . X=A . B )
D. ( X=overline{A+B} )
12
63 In n-type semiconductor, majority charge carriers are
A. electrons
B. neutrons
c. holes
D. protons
12
64 In metals, the conduction bands are
incompletely filled orbitals that allow electrons to flow.
A. true
B. false
c. orbit
D. none of these
12
65 Assertion
Intrinsic semiconductors are undoped
Reason

Holes in the valence band are vacancies
created by electrons that have been thermally excited to the conduction
band
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect

12
66 11. If in a pn junction diode, a square input signal of 10 V is
applied as shown,
-sv
then the output signal across R, will be
(a) +5 V
(b)
– 10 V
– 10v
(d)
-5V
(AIEEE 2007)
12
67 With a neat circuit diagram, explain the working of a single stage ( C E ) amplifier. Draw the frequency response curve and discuss the results. 12
68 A student wants to use two p-njunction
diodes to convert alternating current into direct current. Draw the labelled
circuit diagram he/she would use and explain how it work
12
69 The intrinsic conductivity of
germanium at ( 27^{circ} mathrm{C} ) is ( 2.13 mathrm{mho} / mathrm{m} )
and mobilities of electrons and holes
are 0.38 and ( 0.18 m^{2} / V s ) respectively. The density of charge carriers is
( mathbf{A} cdot 2.37 times 10^{19} / m^{3} )
B. ( 3.28 times 10^{19} / m^{3} )
C. ( 7.83 times 10^{19} / m^{3} )
D. ( 8.47 times 10^{19} / m^{3} )
12
70 Resistor is coloured as green – orange –
yellow – gold,its resistance will be:
A. ( 53 times 10^{4} pm 10 % )
В. ( 54 times 10^{4} pm 10 % )
c. ( 42 times 10^{4} pm 10 % )
D. ( 53 times 10^{4} pm 5 % )
12
71 How is a Zener diode fabricated? What
causes the setting up of high electric field even for small reverse bias voltage
across the diode?
Describe, with the help of a circuit diagram, the working of Zener diode as
a voltage regulator.
12
72 1. Three semiconductors are arranged in the increasing order
of their energy gap as follows. The correct arrangement is
(a) Tellurium, germanium, silicon
(b) Tellurium, silicon, germanium
(c) Silicon, germanium, tellurium
(d) Silicon, tellurium, germanium
12
73 The current gain in the common emitter amplifier mode of a transistor is ( 10 . ) The input impedance is ( 20 k Omega ) and load of resistance is ( 100 k Omega ). The power gain is :
A. 300
в. 500
( c cdot 200 )
D. 100
12
74 The circuit as shown in figure, the
equivalent gate is
A. NOR gate
B. oR gate
c. AND gate
D. NAND gate
12
75 Indium impurity in germanium makes
A. n-type
B. p-type
c. insulator
D. intrinsic
12
76 Match List-1 with list-2
( begin{array}{ll}text { List-1 } & text { List-2 } \ text { A. Emitter } & text { E. Transistor } \ text { B. Base } & text { F. Moderately doped } \ text { C. Collector } & text { G. Lightly doped } \ text { D. Transfer of resistance } & text { H. Heavily doped } \ text { I. largest physical size }end{array} )
A. A-F B-E C-H,I D-G
B. A-G B-F.I C-E D-H
c. A-HB-G C-F,I D-E
D. A-E B-H,I C-G D-F
12
77 What are Forward and Reverse bias
conditions of a Diode?
12
78 The circuit has two oppositely connect
ideal diodes in parallel. What is the
current following in the circuit?
A ( .1 .33 A )
в. 1.71 А
( c .2 .00 A )
D. ( 2.31 A )
12
79 The output of the given combination of gates is equivalent to:
A. NAND
B. OR
( c . ) AND
D. NOR
12
80 The principle of LASER action involves:
A. Amplification of particular frequency emitted by the system
B. Population inversion
c. Stimulated emission
D. All of the above
12
81 To reverse bias a photo-diode:
A. cathode of the detector is set at a higher electric potential than the anode.
B. anode of the detector is set at a higher electric potential than the cathode.
C. cathode and anode are set at the same electric
potential.
D. none of the above.
12
82 59. For the given combination of gates , if the logic states of
inputs A, B, C are as follows A = B = C = 0 and A =B=1,
C = 0, then the logic states of output D are
B
(a) 0,0
(c) 1,0
(b) 0,1
(d) 1,1
al
12
83 State whether given statement is True or False

The majority charge carriers in ( p ) -type semiconductor are electrons.
A . True
B. False

12
84 A potential barrier V volts exists across a P-N junction. The thickness of the
depletion region is ‘d’. An electron with velocity ‘v’ approaches P-Njunction from N-side. Find the velocity of the electron crossing the junction.
12
85 The band gaps of a conductor, semiconductor and insulator are
respectively ( boldsymbol{E} boldsymbol{g}_{1}, boldsymbol{E} boldsymbol{g}_{2} ) and ( boldsymbol{E} boldsymbol{g}_{3} . ) The
relationship between them can be given
as.
A ( . E g_{1}=E g_{2}=E g_{3} )
в. ( E g_{1}<E g_{2}E g_{2}>E g_{3} )
D. ( E g_{1}E g_{3} )
12
86 For a common emitter amplifier,
current gain is ( 60 . ) If the emitter current is ( 6.6 m A ), the base current is
( mathbf{A} cdot 1.08 mathrm{mA} )
B . ( 10.8 mathrm{mA} )
c. ( 0.108 m A )
D. ( 8.01 mathrm{mA} )
12
87 In a CE amplifier, the input ac signal to be amplified is applied across.
A. Forward biased emitter-base junction
B. Reverse biased collector-base junction
c. Reverse biased emitter-base junction
D. Forward biased collector-base junction
12
88 A common emitter amplifier circuit,
built using an npn transistor, is shown
in the figure. Its dc current gain is
( 250, R_{C}=1 k Omega ) and ( V_{C E} ) to reach
saturation?
A. ( 100 mu A )
B. ( 7 mu A )
( c .40 mu A )
D. ( 10 mu A )
12
89 The efficiency of a full wave rectifier is?
A. Half of half wave rectifier
B. 3 times of half wave rectifier
C. Double of half wave rectifier
D. Same as half wave rectifier
12
90 To achieve DC from ( A C, A C ) be applied
across
( A cdot B D )
B. AC
( c ). ВС
( D cdot c D )
E. Al
12
91 On increasing the reverse bias to a large value in a p-njunction, diode
current
A. Increases slowely
B. Remains fixed
c. suddenly increases
D. Decreases slowly
12
92 Barrier potential of a p-njunction diode does not depend on –
A. diode design
B. temperature
c. forward bias
D. doping density
12
93 Reverse saturation current of a diode:
A. is independent of temperature
B. increases with increase in temperature
C. decreases with increase in temperature
D. may increase or decrease with increase in temperature depending on the semiconductor
12
94 The process of converting alternating current into direct current is known as
A. modulation
B. amplification
c. detection
D. rectification
12
95 Which of the following table helps in representing the previous and next of the sequential circuit prior to and after the clock pulse respectively?
A. Truth table
B. Characteristic table
c. Excitation table
D. None of the above
12
96 What is forward biasing and reverse biasing of a diode? 12
97 The
determines how electrons respond to forces (via the concept of effective mass).
A. electrostatic forces
B. dispersion relation
c. magnetic force
D. lorentz force
12
98 An AND gate is followed by a NOT gate in series. With two inputs ( boldsymbol{A} & boldsymbol{B} ), the
Boolean expression for the out put ( Y ) will be :
A. ( A . B )
B. ( A+B )
( c cdot overline{A+B} )
D. ( overline{A . B} )
12
99 For a transistor, the current ratio ( boldsymbol{alpha}_{d c}= ) ( frac{69}{70} . ) The current gain ( beta_{d c} ) is
( mathbf{A} cdot 66 )
B. 67
( c cdot 69 )
D. 71
12
100 ( boldsymbol{E}_{boldsymbol{g}}(boldsymbol{T})=boldsymbol{E}_{boldsymbol{g}}(boldsymbol{m})-frac{boldsymbol{alpha} boldsymbol{T}^{2}}{boldsymbol{T}+boldsymbol{beta}} ) is
the Varshni’s empirical expression,then
the value of ( m ) is
12
101 If to an intrinsic semiconductor, a pentavalent element is added as impurity, one get extrinsic semi conductor of ( _{–}-_{-}- ) type
A. n-type
B. p-type
C. intrinsic
D. Both A and B
12
102 The value of current in the above
diagram is (diode assumed to be ideal
one)
A . 0
в. ( 1 A )
c. ( 1.66 A )
D. 15A
12
103 LCD stands for:
A. Light Carrying Diode
B. Liquid Crystal Display
C . Long Crystal Display
D. Light Crystal Display
12
104 A semiconductor is a material with a
small but non-zero band gap that
behaves as an insulator at absolute
zero but allows thermal excitation of
electrons into its
temperatures that are below its melting point.
A. номо
B. valence band
c. conduction band
D. LUMO
12
105 44. In the circuit shown in the figure, the base current le 1S
10 uA and the collector is 5.2 mA. The value of VBE is
RE 3 500 k22
13 lctlB
Rc = 1 k12
+ 5.5 V
INCE
T-vec
-VBE
(a) 0.1 V
(c) 0.5 V
(b) 0.3 V
(d) 0.7 V
12
106 Draw V-I characteristics of a p-n junction diode. Answer the following questions, giving reasons:
(i) Why is the current under reverse bias almost independent of the applied upto a critical voltage?
(ii) Why does the reverse current show a sudden increase at the critical voltage?
Name any semiconductor device which operates under the reverse bias in the
breakdown regions
12
107 In an ( n ) -p-n transistor circuit, the collector current is ( 10 m A ). If ( 90 % ) of the
electrons emitted reach the collector,
then
This question has multiple correct options
A. the emitter current, the will be ( 9 m A )
B. the base current will be ( 1 m A )
c. the emitter current will be ( 11.11 m A )
D. The base current will be ( 1.11 mathrm{mA} )
12
108 toppr
Q Type your question
configuration is :
( A )
B.
( c )
( D )
12
109 Which of the following gates corresponds to the truth table given below?
( A B Y )
[
begin{array}{ccc}
1 & 1 & 0 \
1 & 0 & 1 \
0 & 1 & 1
end{array}
]
( 0 quad 0 quad 1 )
A. xor
в. ок
c. NAND
D. NOR
12
110 In the valance band, the current is due
to
A. the presence of electrons
B. the presence of holes
c. the presence of both electrons and holes
D. none of the above
12
111 70. A moving-coil ammeter is to be adapted to detect small
alternating currents. Which of the following diagrams
shows how a diode could be connected in order to make
the conversion?
12
112 Production of ICs is preferred in
industrial scales because:
A. it reduces the cost of production.
B. it makes the task of fabrication of a circuit easier
c. it improves the efficiency of the circuit.
D. specifications of a circuit is same for all applications
12
113 Of the diodes shown in the following
diagrams, the reverse biased diode is
( mathbf{A} )
B.
( mathbf{c} )
D.
12
114 In the Boolean algebra : ( boldsymbol{A}+boldsymbol{B}= )
A. ( bar{A}+bar{B} bar{hline} bar{B} )
в. А.
c. ( overline{bar{A}}+overline{bar{B}} )
12
115 the intrinsic semiconductor at room
temperature is
12
116 In the case of forward biasing of a p-n junction diode,which one of the
following figure correctly depicts the
direction of conventional current?
( A )
( B )
( c )
( D )
12
117 Which one of the following statements is not correct of for a junction transistor?
A. The base region is very thin.
B. Emitter is more heavily doped as compared to collector.
c. Emitter and collector can be interchanged
D. The surface area of collector is quite large as compared to emitter.
12
118 You are given two circuits as shown in Fig., which consist of NAND gates. Identify the logic operation carried out by the two circuits. 12
119 At ( 0 K ) temperature, a p-type
semiconductor
A. has equal number of holes and free electrons
B. has few holes but no free electrons
c. has few holes and few free electrons
D. does not have any charge carriers
12
120 An oscillator is basically an amplifier
with gain:
A. Less than unity
B. More than unity
c. zero
D. 0.5
12
121 Explain the formation of energy bands in solids. On the basis of energy bands distinguish between a metal, a semiconductor and an insulator. 12
122 The following symbol represents
A. NAND gate
B. NOT gate
c. AND gate
D. or gate
12
123 For transistor action, which of the
following statements are correct:
This question has multiple correct options
A. Base, emitter and collector regions should have similar size and doping concentrations
B. The base region must be very thin and lightly doped
C. The emitter junction is forward biased and collector junction is reverse biased
D. Both the emitter junction as well as the collector junction are forward biased
12
124 When a p-n-p transistor is operated in
saturation region, then its
A. Base-emitter junction is forward biased and basecollector junction is reverse biased.
B. Both base-emitter and base-collector junctions are reverse biased
C. Both base-emitter and base-collector junctions are forward biased
D. Base-emitter junction is reverse biased and basecollector junction is forward biased.
12
125 Which of the following pairs of
semiconductor devices and the
materials used don’t match?
A. Solar cell : ( C u I n S e_{2} ) as absorber and ( C d S ) as collector
B. LED:GaAs and AlGaAs
c. optical fibre : Vitreous high silica glass doped with germanium
D. Semiconductor Laser: NdYAG
12
126 The attached figure shows the
characteristics of:
A. Zener diode
B. Avalanche diode
C. Photodiode
D. LED
12
127 Which of the following symbol represents a universal gate?
( A )
в.
( c )
D.
12
128 In a common emitter transistor
amplifier ( beta=60, R_{0}=5000 Omega ) and
internal resistance of a transistor is
500Omega. The voltage amplification of amplifier will be
A . 500
в. 460
c. 600
D. 560
12
129 2. Two identical capacitors A and B are charged to the same
potential V and are connected in two circuits at t = 0, as
shown in figure. The charge on the capacitors at time t= CR
are respectively
R
(a) VC, VC
(b) C vc
VC VC
)
(0) VC vc
12
130 Transistors used for making NOT
gate.why?
12
131 Energy band gap size for semiconductors is in the range
( e V )
( mathbf{A} cdot 1-2 )
B. ( 2-3 )
( mathbf{c} cdot 3-4 )
( mathrm{D} cdot>4 )
12
132 Which of the following material(s) is/are used in making a solar cell? This question has multiple correct options
A. Silicon
B. Polycrystalline Thin Films
c. Gallium Arsenide
D. Both A and B
12
133 20. In the following circuit, the equivalent resistance between
A and B is
2003
– 10 V
d
(b) 1032
(d) 2012
(c) 1692
12
134 Which among the following devices work on the basis of photo-voltaic effect?

This question has multiple correct options
A. Photo-diode
B. Light Emitting Diode (LED)
c. solar Cell
D. None of these

12
135 State whether given statement is True or False
The ( p ) -n type junction can act as a semiconductor diode
A. True
B. False
12
136 Which logic gate produces LOW output when any of the inputs is HIGH?
A. AND
в. ов
c. NAND
D. NOR
12
137 Which one of the following represents
forward bias diode?
( A )
в.
( c )
D.
12
138 Conductors are materials having an
electrical conductivity :
A . greater than ( 10^{3} ) s/cm
B. between ( 10^{-8} ) to ( 10^{3} ) s/cm
C . equal to ( 10^{-8} mathrm{S} / mathrm{cm} )
D. zero
12
139 A transistor has ( beta=40 . ) A change in
base current of ( 100 mu ) A, produces
change in collector current
A. ( 40 times 100 m A )
в. ( (100-40) m A )
c. ( (100+40) m A )
D. ( 100 / 40 m A )
12
140 At absolute zero, a semiconductor is an
insulator because
A. No electron is present in the conduction band
B. All electrons occupy the valence band
C. The value of ( E_{G} ) is large
D. All of the above
12
141 Energy gap between valence band and conduction band of a semiconductor is
A. Zero
B. Infinite
( c cdot 1 e V )
D. 10 eV
12
142 3. In a full wave rectifier circuit operating from 50 Hz mains
frequency, the fundamental frequency in the ripple would be
(a) 70.7 Hz
(b) 100 Hz
(c) 25 Hz
(d) 50 Hz (AIEEE 2005)
12
143 The electrical conductivity of a semiconductor increases when
radiation of the wavelength shorter than ( 2480 n m ) is incident on it.The bandgap (in eV) for the semiconductor is
A . 0.5
B. 0.9
( c .0 .7 )
D. 1.
12
144 Write down 5 difference between N-type and P-type semiconductors. 12
145 Give the circuit symbol of a diode. 12
146 In a solar cell current is generated due to bond breakage in which region?
A. Depletion region
B. n-region
c. p-region
D. None of these
12
147 The circuit shown below is working as a
( 8 V ) de regulated voltage source. When
( 12 V ) is used as input, the power
dissipated (in ( boldsymbol{m} boldsymbol{W} ) ) in each diode is;
(considering both zener dioses are
identical)
12
148 The transducer used in television
transmission works on the principle of
A. Electromagnetic induction
B. Photoelectric effect
c. Raman’s effect
D. Rayleigh’s effect
12
149 A Zener diode is connected to a battery
and a load as shown below: The current
( boldsymbol{I}, boldsymbol{I}_{Z} ) and ( boldsymbol{I}_{boldsymbol{L}} ) are respectively :
A ( .12 .5 mathrm{mA}, 735 mathrm{mA}, 5 mathrm{mA} )
B. ( 12.5 mathrm{mA}, 5 mathrm{mA}, 7.5 mathrm{mA} )
c. ( 15 mathrm{mA}, 7.5 mathrm{mA}, 7.5 mathrm{mA} )
D. ( 15 mathrm{mA}, 5 mathrm{mA}, 10 mathrm{mA} )
12
150 41. In question 38, the voltage gain of the amplifier is
(a) 5
(b) 50
(c) 500
(d) 5000
12
151 Fermi energy level for intrinsic semiconductors lies
A. At middle of the band gap
B. Close to valence band
c. close to conduction band
D. None of the above
12
152 Draw a diagram of show how NAND gates can be combined to obtain an OR gate.(Truth table is not required). 12
153 A germanium specimen is doped with aluminum. The concentration of
acceptor atoms is ( 10^{21} ) atoms ( / m^{3} ). Given that the intrinsic concentration of
electron-hole pairs is ( 10^{19} / m^{3}, ) the concentration of electrons in
the specimen is
A ( cdot 10^{17} / m^{3} )
В. ( 10^{15} 5 m^{3} )
c. ( 10^{4} / m^{3} )
D. ( 10^{3} / m^{3} )
12
154 With what considerations in view, a
photodiode is fabricated?

State its working with the help of a suitable diagram.
Even though the current in the forward bias is known to be more than in the
reverse bias, yet the photodiode works in revers bias. What is the reason?

12
155 ( boldsymbol{alpha}=mathbf{0 . 9 9} ) for a CE transistor amplified
circuit. The input resistance is equal to ( 1 mathrm{K} Omega ) and load resistance is equal to 10
K ( Omega . ) The voltage gain of the circuit is
A . 99
в. 990
c. 9900
D. 99000
12
156 LASER is an acronym for light amplification by
A. Stimulated energetic radiation
B. Spontaneous emission of radiation
c. Stimulated emission of radiation
D. Spontaneous emission of radio waves
12
157 In p-njunction, avalanche current flows in circuit when biasing is
A. forward
B. reverse
c. zero
D. excess
12
158 58. The diagram shows a logic network.
8 NANDO
YAND
NAND
NOT
AND
NANDO
NOT
Which single gate is equivalent to the network?
(a) EX-NOR
(b) NOR
(c) EX-OR
(d) OR
son 1
12
159 In a common -base amplifier, the phase difference between the input signal voltage and output voltage is :
A ( cdot frac{pi}{4} )
в. ( pi )
c. 0
D.
12
160 If a signal passing through a gate is inhibited by sending a LOW into one of the inputs, and the output is HIGH, the gate is ( a(n) )
A. AND
B. NAND
c. NOR
D. or
12
161 What is rectification? Draw the circuit
diagram of half wave rectifier and explain its working. Show the input ac voltage and output voltage waveforms from the rectifier circuit.
12
162 Current in the circuit will be
( A cdot frac{5}{A 0} )
( B cdot frac{5}{50} A )
( c cdot frac{5}{10} A )
( D cdot frac{5}{20} A )
12
163 What is rectification? Explain the working of a full-wave rectifier with a diagram. What is a zener diode? How
will a zener diode be connected in a
circuit generally?
12
164 Electrical conductivity of a semiconductor increases when em
radiation of ( lambda<2480 n m ) is incident on
it. The band gap in (ev) for the semiconductor is
( mathbf{A} cdot 1.1 e V )
B . ( 2.5 e V )
c. ( 0.7 e V )
( mathbf{D} cdot 0.5 e V )
12
165 The intrinsic semi conductor becomes
an insulator at
( mathbf{A} cdot 0^{circ} C )
в. ( 0 K )
c. ( 300 K )
D. ( -100^{circ} mathrm{C} )
12
166 Number of electrons in the valence shell
of a semiconductor is
A .
B. 2
( c .3 )
( D )
12
167 For both pure and doped silicon,
calculate the probability that a state at
the bottom of the silicon conduction
band is occupied?
( A cdot 5.20 times 10^{-2} )
B . ( 1.40 times 10^{-2} )
c. ( 10.5 times 10^{-2} )
D. ( 14 times 10^{-2} )
12
168 In the case of p-njunction diode at a high value of reverse bias, the current rises sharply. The value of reverse bias is known as
A. cut off voltage
B. zener voltage
c. inverse voltage
D. critical voltage
12
169 To obtain p-type Si semiconductor, we need to dope pure Si with
A. Aluminium
B. Phosphorous
c. oxygen
D. Germanium
12
170 The space-charge region on either side
of the junction together is known as depletion region because
A. neither electrons nor holes exist in this region
B. the electrons and holes taking part in the initial movement across the junction freed the region of its free charges.
c. the electrons and holes in this region are immobile
D. None of these
12
171 (a) NAND gates are also called universal gate. Why?
(b) Draw a logic symbol of OR gate.
(c) Write the value of output ( y ) in the
given circuit:
(d) Write the name of the diode used in
voltage regulation.
Input ( a=1-square ) output ( y )
12
172 The level formed due to impurity atom, in the forbidden energy gap, very near to the valence band in a P-type semiconductor is called
A. an acceptor level
B. a donor level
c. a conduction level
D. none of these
12
173 Write the name of device ( ^{prime} X^{prime} ) in the
following given diagram. Explain its working making its circuit diagram.
12
174 A diode having potential difference ( 0.5 V ) across its junction which does not depend on current, is connected in
series with resistance of ( 20 Omega ) across
source. If ( 0.1 A ) current passes through
resistance then what is the voltage of the source?
A. ( 1.5 V )
в. ( 2.0 V )
( mathrm{c} .2 .5 mathrm{V} )
D. ( 5 V )
12
175 The reverse saturation current of a
silicon diode
A. doubles for every ( 10^{circ} mathrm{C} ) increase in temperature
B. does not change with temperature
C. halves for every ( 1^{circ} mathrm{C} ) decrease in temperature
D. increases by 1.5 times for every ( 2^{circ} C ) increment in temperature
12
176 Write he name of any one doped semiconductor used for making light emitting diode (LED) 12
177 A point light source are located at ( P_{1} ) as shown in the figure in which all sides of the polygon are equal. The intensity of illumination at ( P_{2} ) is ( 8 frac{W}{m^{2}}, ) what will be
the intensity of illumination at ( P_{3} )
A ( cdot 3 sqrt{3} frac{W}{m^{2}} )
в. ( 6 frac{W}{m^{2}} )
с. ( _{8^{2}} frac{W}{^{2}} )
D. ( sqrt{3} frac{w}{m^{2}} )
12
178 If a full wave rectifier circuit is
operating from ( 50 H z ) mains, the
fundamental frequency in the ripple will
be
( mathbf{A} cdot 25 H z )
B. ( 50 mathrm{Hz} )
c. ( 70.7 mathrm{Hz} )
D. ( 100 H z )
12
179 LEDs have the following advantages over conventional incandescent low
power lamps:
A. Long life and ruggedness
B. Low operational voltage and less power
c. Fast on-off switching capability,
D. All of the above
12
180 Which of the following logic gates is an universal gate?
A. or
в. NOT
c. AND
D. NAND
12
181 Boolean relation at the output stage- ( boldsymbol{Y} )
for the following circuit is:
A ( . bar{A}+bar{B} )
в. ( A cdot B )
( c cdot bar{A} cdot bar{B} )
D. ( A+B )
12
182 Which of the following is/are optoelectronic devices?
A. photodiodes
B. solar cells
c. light emitting diodes
D. all of the above
12
183 Which of the following is/are true regarding breakdown voltage of Zener
diode?
A. If the reverse bias voltage across a p-njunction diode is increased, at a particular voltage the reverse current suddenly decreases to a large value
B. The holes in the n-side and the conduction electrons in the p-side are accelerated due to the reverse bias voltage.
C. The voltage at which the rate of creation of holeelectron pairs is increased leading to the increased current is called avalanche breakdown
D. None of the above
12
184 The output Y of the gate circuit shown
in the fig is
( mathbf{A} cdot bar{A}+bar{B} )
B. ( overline{A+bar{B}} )
( c cdot overline{A+B} )
( D cdot A+B )
12
185 The following truth table is for which
gate?
( begin{array}{lll}A & B & Y=A+B \ 0 & 0 & 0 \ 0 & 1 & 1 \ 1 & 0 & 1 \ 1 & 1 & 1end{array} )
A. AND
B. OR
c. Nor
D. NAND
12
186 Explain the working of a common base transistor amplifier with the help of a circuit diagram. The load resistance of output circuit is ( 600 k Omega ) and resistance
of input circuit is ( 150 p Omega ) in a common
base amplifier. If current amplification
is ( 0.90, ) then calculate the voltage amplification.
12
187 Calculate the probability that a donor
state in the doped material is
occupied?
A. 0.824
B. 0.08
c. 0.008
D. 8.2
12
188 Box
72. A semiconductor diode
and a resistor of constant
resistance are connected
in some way inside a
box having two external
terminals. When a potential difference V of 1 Vis applied,
I = 25 mA. If potential difference is reversed, I = 50 mA.
Forward resistance and diode resistance are
(a) 40 2,20 22
(b) 40 2,40 12
(c) 0 12,
(d) 622, 12 22
12
189 3. A doped semiconductor has impurity levels 30 meV below
the conduction band. In a thermal collision, an amount kT
of energy is given to the extra electron loosely bound to
the impurity of ion. This electron just manages to be in
the conduction band. The value of temperature T is
(a) 3 K
(b) 34 K
(c) 34.8 K
(d) 348 K
12
190 The output of an AND gate is connected to both the inputs of a NOR gate, then this circuit will act as a
A. or gate
B. NOR gate
c. AND gate
D. NOT gate
E. NAND gate
12
191 w.”15 ivsiv
circuit is
( A )
B.
[
left|begin{array}{lll}
A & B & Y \
0 & 0 & 1 \
0 & 1 & 1 \
1 & 0 & 1 \
1 & 1 & 1
end{array}right|
]
( c )
( D )
12
192 The circuit given represents which of
( log i c ) operations
A. AND
B. NOT
( c . ) ов
D. NOR
12
193 Optoelectronic devices work on:
A . light
B. electrical current
c. both ( A ) and ( B )
D. none of the above
12
194 The distinction between conductors,
insulators and semiconductors is
largely concerned with
A. their ability to conduct current
B. the type of crystal lattice
c. binding energy of their electrons
D. relative widths of their energy gaps
12
195 In a sample of semi conductor
mobilities of electrons and holes are
( 24 times 10^{3} c m^{2} V^{-1} S^{-2} ) and ( 0.2 times )
( 10^{3} mathrm{cm}^{2} V^{-1} S^{-1} ) respectively. If the
density electrons is ( 0.8 times 10^{14} mathrm{cm}^{-3} )
and that of holes is ( 0.4 times 10^{14} mathrm{cm}^{-3} )
Find the nature of semi conductor and
its conductivity
12
196 (A) What do you mean by barrier
potential of diode?
(B) With help of a diagram explain the working of a full wave rectifier.
12
197 Let ( n_{p} ) and ( n_{e} ) the number of holes and
conduction electrons in an intrinsic
semiconductor. Then:
A ( cdot n_{p}>n_{e} )
в. ( n_{p}=n_{e} )
c. ( n_{p}<n_{e} )
D ( cdot n_{p} neq n_{e} )
12
198 Identify the gate and match ( A, B, Y ) in
bracket to check.
( mathbf{A} cdot operatorname{AND}(A=1, B=1, Y=1) )
B. OR ( (A=1, B=1, Y=0) )
C . NOT ( (A=1, B=1, Y=1) )
D. XOR ( (A=0, B=0, Y=0) )
12
199 On increasing the reverse bias to a
large value in p-njunction diode then value of current
A. remain fixed
B. increases slowly
c. decreases slowly
D. suddenly increases
12
200 What is a rectifier? With a suitable
circuit diagram, describe the action of
a full wave rectifier by drawing input and output waveforms.
12
201 toppr ( E )
Q Type your question.
0
( A )
( begin{array}{lll}A & B & Y \ 0 & 0 & 1end{array} )
010
101
в. ( A B cdot Y )
( 0 quad 0 quad 1 )
0.11
101
c.
( A B Y )
00
011
101
110
D. ( A B Y )
00.1
011
12
202 The figure represents a voltage regulator circuit using a Zener diode. The breakdown voltage of the Zener diode is ( 6 V ) and the load resistance is
( R_{L}=4 k Omega . ) The series resistance of the
circuit is ( R_{i}=1 k Omega . ) If the battery
voltage ( V_{B} ) varies from ( 8 V ) to ( 16 V ), what
are the minimum and maximum values
of the current through Zener diode?
A. ( 0.5 mathrm{mA} ; 6 mathrm{mA} )
B. ( 0.5 mathrm{mA} ; 8.5 mathrm{mA} )
c. ( 1.5 m A ; 8.5 m A )
D. ( 1 mathrm{mA} ; 8.5 mathrm{mA} )
12
203 State whether given statement is True or Falsel
n p-njunction diode, the current in the reverse biased junction is generally very small
A. True
B. False
12
204 AND gate
A. it has no equivalence to switching circuit.
B. it is equivalent to series switching circuit.
C. it is equivalent to parallel switching circuit
D. it is a mixture of series and parallel switching circuit.
12
205 2. The electrical conductivity of a semiconductor increases
when electromagnetic radiations of wavelength shorter
than 2480 nm is incident on it. The band gap (in eV) for
the semiconductor is
(a) 0.7 eV
(b) 0.5 eV
(c) 0.6 eV
(d) 1.1 eV (AIEEE 2005)
12
206 LEDs are better than conventional
incandescent power lamps because:
A. LEDs have higher efficiency.
B. LEDs look beautiful.
c. LEDs are cheap.
D. all of the above
12
207 Two triodes having amplification factors 30 and 21 and plate resistances
( 5 k Omega ) and ( 4 k Omega ) respectively are connected in parallel. The composite amplification factor of the system is
A . 25
B . 50
c. 75
D. 100
12
208 The ( V-I ) characteristic of a silicon diode
is shown in the figure. Calculate the
resistance of the diode at
(a) ( I_{D}=15 m A ) and
(b) ( V_{D}=-10 V )
12
209 7. In the following circuits, PN-junction diodes D1, D2 and
D3 are ideal for the following potential of A and B. The
correct increasing order of resistance between A and B
will be
DR
5.795
(ii) – 5V, – 10 V
(i) – 10 V, -5V
(iii) – 4V, – 12V
(a) (i) < (ii) < (iii)
(c) (ii) = (iii) < (i)
(b) (iii) <(ii) < (i)
(d) (i) = (iii) < (ii)
12
210 Draw a circuit diagram of a full wave rectifier. Explain its working and draw input and output waveforms. 12
211 In a common emitter (CE) amplifier having a voltage gain ( G, ) the transistor
used has transconductance 0.03 mho
and current gain ( 25 . ) If the above transistor is replaced with another one with transconductance 0.02 mho and
current gain ( 20, ) the voltage gain will be
A ( cdot frac{2}{3} G )
в. ( 1.5 G )
c. ( frac{1}{3} G )
D. ( frac{5}{4} G )
12
212 Currents flowing in each of the following
circuits ( A ) and ( B ) respectively are
( A cdot 1 A, 2 A )
B. 2 A, 1 A
( c cdot 4 A, 2 A )
D. 2 A, 4 A
12
213 In a zener-regulated power supply a
zener diode with ( V_{z}=6 ) volt is used for
regulation. The load current is to be ( 4 m A ) and the unregulated input is 10
volt. What should be the value of series
resistor ( boldsymbol{R}_{s} ) if the current through diode
is five times the load current?
12
214 In a semiconductor, the forbidden energy gap between the valence band
and the conduction band is of the order
is
A . ( 1 mathrm{MeV} )
B. ( 0.1 mathrm{MeV} )
c. ( 1 e V )
D. ( 5 e V )
12
215 Symbolic representation of NOR gate is?
( A )
в.
( c )
D.
12
216 The logic circuit in the figure represents characteristics of which logic gate?
A . NOR
B. OR
c. NAND
D. NOT
12
217 Ciascu
65. A capacitor is to be used to provide smoothing for a half
wave rectifier. In which of the following diagrams is the
capacitor correctly connected?
Load
=
Load
Load
Load
12
218 What is an energy gap?
A. the space between two orbital shells
B. the energy equal to the energy acquired by an electron passing a ( 1 V ) electric field
C. the energy band in which electrons can move freely
D. an energy level at which an electron can exist
12
219 An increase in temperature produces
A. an increase in the minority carrier current
B. an decrease in the minority carrier current
C. an increase in the majority carrier current
D. no carrier current
12
220 dentify the operation performed by the
circuit given below:
A . NOT
B. AND
( c . ) ов
D. NAND
12
221 Which logic gates is represented by the following combination of logic gates?
A. OR
B. NAND
c. AND
D. NOR
12
222 What is the number density of donor atoms which must be added to a pure
germanium semiconductor to produce an N-type semiconductor of
conductivity ( 6.4 X 10^{2} ) oh ( m^{-1} m^{-1} ) ? The mobility of electrons in N-type germanium is ( 4 X 10^{-1} m^{2} V^{-1} s^{-1} )
Neglect contribution of holes to conductivity.
A ( cdot 10^{20} m^{-3} )
B. ( 10^{21} m^{-3} )
( mathrm{c} cdot 10^{22} mathrm{m}^{-3} )
D. ( 10^{23} ) s ( ^{-3} )
12
223 What is photo diode? Mention its one
use.
12
224 13. This question has Statement I and Statement II. Of the
four choices given after the statements, choose the one
that best describes the two statements.
Statement I: Higher the range, greater is the resistance on
ammeter.
Statement II: To increase the range of ammeter,
additional shunt needs to be used across it.
(a) Statement I is true, statement II is true, statement II is
not the correct explanation of statement I.
(b) Statement I is true but statement II is false.
(c) Statement I is false but statement II is true.
(d) Statement I is true but statement II is true, statement
II is the correct explanation of statement I
(JEE Main 2013)
12
225 What is the depletion region in pn
junction?
12
226 The combination of the gates shown
below produces where ( G_{1} ) to ( G_{4} ) are NOR
gates:
A. AND gate
B. xoR gate
c. NOR gate
D. NAND gate
12
227 150 2
5092
12. The circuit shown in the following
figure contains two diodes, each
with a forward resistance of 50
and with infinite backward
resistance. If the battery voltage
is 6V, the current through 100 12
resistance (in amperes) is:
(a) Zero
(b) 0.02
(c) 0.03
(d) 0.036
1002
12
228 39. In question 38, the ac current gain is
(a) o
(b) 1
(c) 0.1
(d) 10000
12
229 Zener diodes with breakdown voltage ranging over ( 2 mathrm{V}-200 mathrm{V} ) are
commercially available. Breakdown voltage of a zener diode
A. Increases with increasing doping concentration
B. Decreases with increasing doping concentration
C. Does not depend on doping concentration
D. May increases or decreases with increasing doping concentration
12
230 A red LED emits light at ( 0.1 W ) uniformly around it. The amplitude of the electric filed of the light at a
distance of ( 1 ~ m ) form the diode is:
A. ( 1.73 mathrm{V} / mathrm{m} )
в. ( 2.45 mathrm{V} / mathrm{m} )
c. ( 5.48 mathrm{V} / mathrm{m} )
D. ( 7.75 V / m )
12
231 Which of the following elements is added to turn artificial diamond into
semi conductors?
A. Beryllium
B. Boron
c. Magnesium
D. Calcium
12
232 The grid voltage of any triode valve is changed from -1 volt to -3 volt and the mutual conductance is ( 3 times 10^{-4} ) mho.
The change in plate circuit current will be
A. ( 0.8 mathrm{mA} )
B. ( 0.6 mathrm{mA} )
c. ( 0.4 mathrm{mA} )
D. ( 1 mathrm{m} )
12
233 The highest occupied energy band is called and lowest
unoccupied energy band is called the
A. Band Gap, conduction band
B. Valence band, Band Gap
c. conduction band, valence band
D. valence band, Conduction band
12
234 What is a hole? Which type of doping
creats a hole?
12
235 In an insulator, the forbidden energy gap between the valence band
and conduction band is of the order of
A. ( 1 mathrm{MeV} )
B. ( 0.1 mathrm{MeV} )
c. ( 1 e V )
D. ( 5 e V )
12
236 What is true about the breakdown
voltage in a zener diode?
A. It decreases when current increases.
B. It destroys the diode.
c. It equals the current times the resistance.
D. It is approximately constant.
12
237 DU
6. In the circuit given below, V(t) is the sinusoidal voltage
source, voltage drop Var(t) across the resistance R
ZVAB
R; = 100 1
R2 = 150 12
(a) is half wave rectified
(b) is full wave rectified
(c) has the same peak value in the positive and negative half
cycles
(d) has different peak values during positive and negative half
cycle
12
238 A zener diode is rated as ( 1 W, ) if given
breakdown voltage is ( 6.2 V ) then max
current it can hold is
A ( .224 m A )
в. ( 161 m A )
( mathrm{c} .239 mathrm{mA} )
D. none of the above
12
239 A 5 V zener diode is used to regulate the
voltage across load resistor ( boldsymbol{R}_{L} ) and the
input voltage varies in between ( 10 mathrm{V} ) to ( 15 mathrm{V} . ) The load current also varies from 5
( mathrm{mA} ) to ( 50 mathrm{mA} ). Find the value of series
resistance R.
Given, ( boldsymbol{I}_{Z}(boldsymbol{m} boldsymbol{i} boldsymbol{n})=boldsymbol{2} boldsymbol{0} boldsymbol{m} boldsymbol{A} )
A . ( 70 Omega )
B. ( 90.91 Omega )
c. ( 142.86 Omega )
D. ( 71.43 Omega )
12
240 The forbidden energy gap for
germanium crystal at ( 0 K ) is
A. ( 0.071 e V )
в. ( 0.71 e V )
c. ( 2.57 e V )
D. ( 6.57 e V )
12
241 toppr
Q Type your question
( A )
3
( c )
( D )
12
242 Assertion
The logic gate NOT can be built using diode
Reason
The output voltage and the input
voltage of the diode have ( 180^{circ} mathrm{C} ) phase difference.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
243 Write the truth table for circuit given in the figure, consisting of NOR gates and identify the logic operation (OR, AND, NOT) which this circuit is performing. (Hint: ( A=0, B=1 ) then ( A ) and ( B ) inputs of
second NOR gate will be 0 and hence
( Y=1 . ) Similarly work out the values of ( Y ) for other combinations of ( A ) and ( B ).
Compare with the truth table of OR,
AND, NOT gates and find the correct
one).
12
244 In insulators (CB is conduction band
and VB is valence band)
A. VB is partially filled with electrons
B. CB is partially filled with electrons
c. ( mathrm{cB} ) is empty and ( mathrm{VB} ) is filled with electrons
D. CB is filled with electrons and VB is empty
12
245 One among the following is doping material in p-type of semiconductor:
A. carbon
B. Indium
c. Arsenic
D. Phosphorous
12
246 The junction diode shown in the figure
is ideal. The current in the circuit is
A ( .20 m A )
B. ( 2 m A )
( c .200 m A )
D. 200 A
12
247 What will be the current flowing through the ( 6 K Omega ) resistor in the circuit shown
where the breakdown voltage of the
zener is ( 6 mathrm{V} ) ?
A ( cdot frac{2}{3} mathrm{mA} )
B. 1mA
c. ( 10 mathrm{mA} )
D. ( frac{3}{2} mathrm{mA} )
12
248 A transistor having ( alpha=0.99 ) is used in
common base amplifier. If the load resistance is ( 0.45 M Omega ) and the dynamic resistance of the emitter junction is
( mathbf{5 0} mathbf{Omega}, ) the voltage gain of the amplifier will be
A .7910
0
в. 8910
( c .9910 )
D. 6910
12
249 For PN junction, the intensity of electric field is ( 1 times 10^{6} mathrm{V} / mathrm{m} ) and the width of
depletion region is 5000 A. The value of
potential barrier=
V.
A . 0.05
B. 0.005
( c .0 .5 )
D. 5
12
250 Integrated circuits are preferred over conventional circuits because:
A. They are very compact in size.
B. They are cheap.
c. They are fast and more efficient.
D. All of the above
12
251 In the Boolean algebra, the following one
is wrong
A ( .1+0=1 )
B. ( 0+1=1 )
c. ( 1+1=1 )
D. ( 0+0=1 )
12
252 In a silicon diode, the reverse current increases from ( 10 mu A ) to ( 20 mu A ). when the
reverse voltage change from ( 2 V ) to ( 4 V )
The reverse ac resistance of the diode is
A ( cdot 1 times 10^{5} Omega )
В. ( 3 times 10^{5} Omega )
c. ( 2 times 10^{5} Omega )
D. ( 4 times 10^{5} Omega )
12
253 The following configuration of gates is equivalent to
A. xon
B. NAND
( c . ) ок
D. None of these
12
254 Identify the gate. 12
255 56. Identify the gate in the figure.
(a) AND
(c) NOR
(b) XOR
(d) NAND
12
256 Among the following, the wrong statement in the case of semiconductor
is:
A. Resistivity is in between that of a conductor and insulator
B. Temperature coefficient of resistance is negative
c. Doping increases conductivity.
D. At absolute zero temperature, it behaves like a conductor
12
257 In a p-njunction photo cell, the value of
the photo electromotive force produced
by monochromatic light is proportional
to
A. the barrier voltage at the p-njunction.
B. the intensity of the light falling on the cell.
C. the frequency of the light falling on the cell.
D. the voltage applied at the p-n junction.
12
258 The current gain of transistor in a
common emitter circuit is ( 40 . ) The ratio
of emitter current to base current is
( mathbf{A} cdot 40 )
B. 41
c. 42
D. 43
12
259 If the forward bias on p-njunction is
increased from zero to ( 0.045 V ), then no
current flows in the circuit. The
contact potential of junction i.e. ( V_{B} ) is
A. zero
B. ( 0.045 V )
C. more than ( 0.045 V )
D. less than ( 0.045 V )
12
260 Why are NOR gates considered as
universal gates?
12
261 State whether given statement is True or False

The probability of electrons to be found in the conduction band of an intrinsic
semiconductor at a
finite temperature decreases
exponentially with increasing bandgap.
A. True
B. False

12
262 What is meant by amplification? Draw a simple circuit of ( n ) -p-n common emitter
transistor amplifier. On the basis of band theory, distinguish between conductor, insulator and semi-
conductor.
12
263 If an intrinsic semiconductor is heated,
the ratio of free electrons to holes is :
A. greater than one
B. less than one
c. equal to one
D. dercease and becomes zero
12
264 In the circuit shown, what will be the
current through the ( 6 V ) zener?
( mathbf{A} cdot 6 m A, ) from ( A ) to ( B )
B. ( 2 m A ), from A to ( B )
( mathrm{c} .2 mathrm{mA}, ) from ( mathrm{B} ) to ( A )
D. Zero
12
265 For a common emitter amplifier,
current gain is ( 60 . ) If the emitter current
is ( 6.6 ~ m A ) the collector current is :
A. ( 0.108 mathrm{mA} )
B. 6.492 m ( A )
c. ( 1.1 mathrm{m} ) А
D. 3.3 ( m A )
12
266 biased has a drop of ( 0.5 % ) which is
assumed to be independent of current.
The current in excess of ( 10 m A )
through the diode produces large joule
heating which damages the diode. If we
want to use a ( 1.5 ~ V ) battery to forward
bias the diode, the resistor used in
series with the diode so that the
maximum current does not exceed
( 5 m A ) is
A ( .2 times 10^{2} Omega )
B . ( 2 times 10^{5} Omega )
C ( cdot 2 times 10^{3} Omega )
D . ( 2 times 10^{4} Omega )
12
267 What is the voltage gain in a common emitter amplifier, when input resistance is ( 3 Omega ) and load resistance is
( 24 Omega ) with ( beta=60 ? )
A. 480
в. 2.4
( c .4 .8 )
D. 8.4
12
268 A semiconductor has equal electron
and hole concentration of ( 2 times 10^{8} m^{-3} )
On doping with a certain impurity, the electron concentration increases to ( 4 x )
( 10^{10} m^{-3}, ) then the new hole
concentration of the semiconductor is
A ( cdot 10^{6} m^{-3} )
B . ( 10^{8} m^{-3} )
D. ( 10^{12} m^{-3} )
12
269 Mention the important considerations required while fabricating a p-n junction diode to be used as a Light Emitting Diode (LED).What should be
the order of band gap of an LED if it is required to emit light in the visible range?
12
270 The Fermi level in intrinsic semi-
conductors at ( 0 K ) temperature lies:
A. Near the conduction band
B. Near the valence band
C. In the middle of valence and conduction band
D. Inside the conduction band
12
271 The majority charge carriers in the emitter of an NPN transistor are
A. pentavalent atoms
B. trivalent atoms
c. electrons
D. holes
12
272 If ( boldsymbol{A}=mathbf{1}, boldsymbol{B}=mathbf{0} ) then the value of ( overline{boldsymbol{A}}+boldsymbol{B} )
in terms of Boolean algebra is
A . ( A )
в. ( B )
c. ( B+A )
D. A.B
12
273 Generally semiconductor can be used safely between the temperatures:
A . -75 and 200
B. 0 and 75
c. -25 and 300
D. -40 and 1000
12
274 When an impurity is doped into semiconductor, the conductivity of the semiconductor
A . increases
B. decreases
c. remains same
D. becomes zero
12
275 The voltage at ( B ) in the figure is :
( A cdot 5.3 V )
В. ( 5.7 V )
( c .6 .3 V )
D. ( 6 V )
12
276 The energy gap in glass at room
temperature is
A. Greater than that in a semiconductor.
B. Less than that in a good conductor
C. Greater than that in a good conductor.
D. Both (1) and (3) are true.
12
277 Choose the correct statement:
A. A p-type semiconductor is positively charged
B. The Boolean expression ( 1 cdot 0=0 )
C. The majority carrier in ( N ) – type semiconductor is hole
D. A transistor cannot be used as a switch
12
278 In insulator
A. valence band is partially filled with electrons
B. conduction band is partially filled with electrons
c. conduction band is filled with electrons and valence
band is empty
D. conduction band is empty and valence band is filled with electrons
12
279 Constant DC voltage is required from a variable AC voltage. Which of the following is correct order of operation?
A. Regulator, Filter, Rectifier
B. Rectifier, Regulator, Filter
c. Rectifier, Filter, Regulator
D. Filter, Regulator, Rectifier
12
280 When a p-n diode is reverse biased, then
A. no current flows
B. the depletion region is increased
C. the depletion region is reduced
D. the height of the potential barrier is reduced
12
281 22. The reading of the ammeter for a silicon diode in the given
circuit is
2002
(a) 13.5mA
(c) 15 mA
(b) 0 (zero)
(d) 11.5 mA
(JEE Main 2018)
12
282 You are given the two circuits as shown In Fig. Show that circuit (a) acts as OR gate while the circuit (b) acts as AND
gate.
12
283 Which is not true:
A. Resistance of metals increases with increasing temperature
B. Resistance of semi-conductors decreases with rise of
temperature
C. Resistance of an electrolyte increases with rise of temperature
D. None of the above
12
284 Identify the semiconductor devices
whose characteristics are given above
in the order ( (a),(b),(c),(d): )
(a)
( (b) )
( (c) )
A. Simple diode, Zener diode, Solar cell, Light dependent resistance
B. Zener diode, Simple diode, Light dependent resistance, Solar cell
C. Solar cell, Light dependent resistance, Zener diode Simple diode
D. Zener diode, Solar cell, Simple diode, Light dependent resistance
12
285 In Boolean algebra, ( boldsymbol{A}+boldsymbol{B}=boldsymbol{Y} ) implies
that
A. sum of ( A ) and ( B ) is ( Y ).
B. ( Y ) exists when ( A ) exists or ( B ) exists or both ( A ) and ( B ) exist
c. ( Y ) exists only when ( A ) and ( B ) both exist
D. ( Y ) exists when ( A ) or ( B ) exist but not when both ( A ) and ( B ) exist
12
286 ( h ) 12
287 Calculate the number of states per
cubic metre of sodium in 3 s band. The
density of sodium is 1013 kgm ( ^{-3} ). How
many of them are empty?
12
288 In semiconductors, at a room
temperature
A. the valence band is partially empty and the conduction band is partially filled.
B. the valence band is completely filled and the conduction band is partially filled.
C. the valence band is completely filled.
D. the conduction band is completely empty.
12
289 If collector current is ( 120 m A ) and base
current is ( 2 m A ) and resistance gain is 3
what is power gain?
A . 180
B. 10800
c. 1.8
D. 18
12
290 An n-type semiconductor is
A. Positively charged
B. Negatively charged
C . Electrically neutral
D. None of the above
12
291 An electrical device which offers a low
resistance to the current in one
direction but a high resistance to the
current in opposite direction is:
A. Current Amplifier
B. Oscillator
c. Power Amplifier
D. Rectifier
12
292 67. In a common-emitter amplifier, using output resistance of
5000 ohm and input resistance of 2000 ohm, if the peak
value of input signal voltage is 10 mV and B = 50, then
the peak value of output voltage is
(a) 5 x 100 V
(b) 2.5 x 104 v
(c) 1.25 V
(d) 125 V
12
293 In Boolean algebra ( boldsymbol{A} . boldsymbol{B}=boldsymbol{Y} ) implies
that:
A. product of ( A ) and ( B ) is ( Y )
B. ( Y ) exists when ( A ) exists or ( B ) exists
c. ( Y ) exists when both ( A ) and ( B ) exist but not when only ( A ) or ( B ) exists
D. ( Y ) exists when ( A ) or ( B ) exists but not both ( A ) and ( B ) exist
12
294 opp
Q Type your question
3
( c )
( D )
12
295 Depletion layer consists of:
A. electrons
B. protons
c. mobile ions
D. immobile ions
12
296 Fill in the blanks.
During reverse bias of the diode there is a small current of the order of micro
ampere due to
12
297 Which are the areas influenced by
electronics?
12
298 To use a transistor as an amplifier:
A. The emitter base junction is forward biased and the base collector junction is reverse biased
B. No bias voltage are required
C. Both junctions are forward biased
D. Both junction are reverse biased
12
299 The saturation condition of transistor
implies that
A. Collector current has highest possible value
B. entire ( V_{c c} ) gets dropped across load resistor
C. it acts as a closed switch with negligible value of resistance
D. all of the above
12
300 The collector supply voltage in ( mathrm{CE} ) transistor amplifier is ( 10 V . ) The base
current is ( 10 mu A ) in the absence of the
signal voltage and the voltage between the collector and the emitter is ( 4 V ). The
current gain ( (beta) ) of a transistor is 200
then the value of the load resistance ( boldsymbol{R}_{boldsymbol{L}} )
( mathbf{A} cdot 2 k Omega )
в. ( 1 k Omega )
( c .3 k Omega )
D. ( 4 k Omega )
12
301 Calculate the current through the given
circuit. (The diodes are ideal)
( 4.6 mathrm{A} )
B. 12 A
( c cdot 1 A )
2
12
302 From the adjacent circuit, the output
voltage is
( mathbf{A} cdot 10 V )
B. ( 100 V )
( mathrm{C} cdot 90 mathrm{V} )
D. zero
12
303 Use of ICs has lead to an increase in
speed of PCs. Current processor speeds
in personal computers is of the order of:
A. ( k H z )
B. ( M H z )
( mathrm{c} . G H z )
D. ( T H z )
12
304 The device that can act as a complete electronic circuit is –
A. Junction diode
B. Integrated circuitt
c. Junction transistor
D. zener diode
12
305 The forward characteristic curve of a
junction diode is shown in Figure.
Calculate the resistance of the diode at:
(1) ( V=0.5 V )
(2) ( mathrm{I}=60 mathrm{mA} )
12
306 Choose the correct option:
Electrical conductivity of a semi conductor-
A. decreases with rise in its temperature.
B. increases with rise in its temperature.
c. does not changes with temperature.
D. first decreases and then increases with rise in temperature.
12
307 Which of the following is unipolar transistor?
A . p-n-p transistor
B. n-p-n transistor
C. Field effect transistor
D. Point contact transistor
12
308 State the difference between laser light and ordinary light 12
309 An oscillator is nothing but an amplifier
with
A. Positive feedback
B. Large gain
c. No feedback
D. Negative feedback
12
310 If the output ( Y ) of the following circuit is
1, the inputs ( A B C ) must be :
A .010
В. 100
( c .101 )
D. 110
12
311 The band structure determines the
conductive behaviour of a solid.
A. True
B. False
12
312 The truth table for NOT gate is
( A )
[
left[begin{array}{ll}
1 & 1 \
0 & 0
end{array}right]
]
B.
[
left[begin{array}{ll}
1 & 0 \
0 & 0
end{array}right]
]
c.
[
left[begin{array}{ll}
1 & 0 \
0 & 1
end{array}right]
]
D.
[
left[begin{array}{ll}
0 & 1 \
1 & 1
end{array}right]
]
12
313 What is a transistor? Mention any two
uses of transistor.
12
314 The avalanche breakdown in ( p-n )
junction is due to
A. shift of Fermi level.
B. cumulative effect of conduction band electron
c. widening of forbidden gap.
D. high impurity concentration.
12
315 The forward biased diode connection is:
( A )
B.
c.
D.
12
316 Explain, with the help of a circuit diagram, the working to a photo-diode. Write briefly how it is used to detect the
optical signals. OR
Mention the important considerations required while fabricating a ( boldsymbol{p}-boldsymbol{n} )
junction diode to be used as a Light Emitting Diode (LED). What should be
the order of band gap of an LED if it is required to emit light in the visible
range?
12
317 At absolute zero temperature a semiconductor behaves like:
A. an insulator
B. a super conductor
c. a good conductor
D. a variable resistor
12
318 Identify the logic gate whose truth table is given below and draw its symbol:
( begin{array}{ccc}boldsymbol{A} & boldsymbol{B} & boldsymbol{Y} \ 0 & 0 & 1 \ 0 & 1 & 1 \ 1 & 0 & 1 \ 1 & 1 & 0end{array} )
12
319 Assertion
Photodiode and solar cell work on same
mechanism.
Reason
Area is large for solar cell.
A. Both Assertion and Reason are correct and Reason is
the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is
not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
320 IR
71. Figure shows a piece
of semiconductor
(pure one) S in
series with a
variable resistor
R and a source of
constant voltage V.
S is heated and the
current is kept constant by adjustment of R. Which of the
following factors will decrease during this process?
1. The drift velocity of the conduction electrons in S
2. The de resistance of S
3. The number of conduction electrons in S
Which of the following is correct?
(a) Only 1
(b) 1 and 2
(c) 1, 2 and 3
(d) Only 3
12
321 For a common-emitter transistor, input
current is ( 5 mu A, beta=100 . ) Circuit is
operated at load resistance of ( 10 k Omega ). The
voltage across collector emitter will be
A. ( 5 v )
B. 10 ( v )
c. ( 12.5 mathrm{v} )
D. 7.5 ( v )
12
322 For the given circuit shown in figure, the
potential of the battery is varied from
( 10 V ) to ( 16 V . ) If by zener diode
breakdown voltage is ( 6 V ), find
maximum current through zener diode.
A. ( 1.5 mathrm{mA} )
в. 3.5 тА
( c .5 m A )
D. 6.5 m
12
323 In a semiconductor, ( 2 / 3 r d ) of the total
current is carried by electrons and
remaining ( 1 / 3 r d ) by the holes. If at this temperature, the drift velocity of
electrons is 3 times that of holes, the
ratio of number density of electrons to that of holes is
( A cdot frac{3}{2} )
B. ( frac{2}{3} )
c. ( frac{5}{3} )
D. ( frac{3}{3} )
( E cdot frac{1}{3} )
12
324 Which of the following circuit type is
based upon time or clock pulse?
A. Combinational circuit
B. Sequential circuit
c. Full adder
D. None of these
12
325 To convert a pure semiconductor into ( n )
type semi-conductor, what type of impurity is added to it?
12
326 The thickness of the depletion region is
of the order of of a
micrometre.
A. one-hundredth
B. one-tenth
c. one-thousandth
D. None of these
12
327 How many NAND gates are required to form an AND gate?
A . 1
B. 2
( c cdot 3 )
( D )
12
328 The logic gate equivalent to the above combination of logic gates is
A. OR
B. NAND
( c cdot ) AND
D. NOR
12
329 For a transistor, the current
amplification factor is ( 0.8 . ) The transistor is connected in
common emitter configuration, the change in collector current when the
base current changes by ( 6 m A ) is
( mathbf{A} cdot 6 m A )
в. ( 4.8 mathrm{mA} )
c. 24 m
D. ( 8 m A )
12
330 For the circuit shown in the figure. The
equivalent resistance between point ( mathbf{A} )
and ( mathrm{B} ) for the two cases ( (mathrm{i}) boldsymbol{V}_{boldsymbol{A}}>boldsymbol{V}_{boldsymbol{B}} )
(ii) ( V_{B}>V_{A} quad ) respectively is
( mathbf{Omega} ) and
respectively ( left(D_{1} text { and } D_{2} ) are ideal right.
diodes)
( A cdot 25, infty )
B. ( 50, infty )
( mathrm{c} cdot infty, 25 )
D. 50.5
12
331 In the adjacent circuit, ( A ) and ( B ) represent two inputs and ( C ) represents the output. The circuit represents.
A. NOR gate
B. AND gate
( a quad ) ” ( quad ) ” gate
( D )
12
332 A potential barrier V volts exists across a P-N junction. The thickness of the depletion region is ‘d’. An electron with velocity ‘v’ approaches P-Njunction from N-side. The velocity of the electron crossing the junction is:
A ( cdot sqrt{v^{2}+frac{2 V e}{m}} )
B. ( sqrt{v^{2}-frac{2 V e}{m}} )
( c )
D. ( sqrt{frac{2 V e}{m}} )
12
333 toppr ( E )
Q Type your question.
0
( A )
( begin{array}{lll}A & B & Y \ 0 & 0 & 1end{array} )
010
101
в. ( A B cdot Y )
( 0 quad 0 quad 1 )
0.11
101
c.
( A B Y )
00
011
101
110
D. ( A B Y )
00.1
011
12
334 The following configuration of gate is
equivalent to
A. NAND gate
B. XOR gate
c. or gate
D. NOR gate
12
335 What is forbidden energy gap(Eg) or band gap?
A. Forbidden energy gap ( E_{g} ) is the difference of energy levels of conduction band and within conduction band
B. Forbidden energy gap ( E_{g} ) is the difference of energy levels of conduction band and valence band.
C. when there is no energy
D. conduction band
12
336 The creation of voltage or electric current in a material upon exposure to light is termed as
A. photo-ionic effect
B. thermi-ionic effect
c. photo-voltaic effect
D. None of these.
12
337 In the bandgap between valence band and conduction band in a material is
( mathbf{5} . mathbf{0} e boldsymbol{V}, ) then the material is
A. semiconductor
B. good conductor
c. superconductor
D. insulator
12
338 4. In the following circuit, the equivalent resistance between
A and B is
τον
2ος
-10 V
-2V
8 Ω
12 Ω
(b) 10Ω
(c) 16 Ω
(d) 20 Ω
12
339 Sum of the two binary number
( (100010)_{2} ) and ( (11011)_{2} ) is
( mathbf{A} cdot(111101)_{2} )
B. ( (111111)_{2} )
( mathbf{c} cdot(101111)_{2} )
D. ( (111001)_{2} )
12
340 What is the value of ( vec{A}+A ) in the
boolean algebra?
( mathbf{A} cdot mathbf{0} )
B.
( c cdot A )
D. ( vec{A} )
12
341 Give band gap Eg value for conductor,
insulator and semiconductor?
A. Conductor ( <1 M e V ), insulation ( geq 6 e V ), semiconductor
( approx 8 e V )
B. Conductor ( <1 M e V ), insulation ( geq 6 e V ), semiconductor
( approx 1 e V )
C. Conductor ( <2 M e V ), insulation ( geq 6 e V ), semiconductor
( approx 1 e V )
D. Conductor< ( 1 mathrm{MeV} ), insulation ( geq 7 mathrm{eV} ), semiconductor
( approx 1 e V )
12
342 In a bridge rectifier, the number of diodes required is
A . 1
B. 2
( c .3 )
( D )
12
343 In a half-wave rectifier circuit operating
from ( 50 mathrm{Hz} ) mains frequency, the fundamental frequency in the ripple would be
A. ( 10 mathrm{Hz} )
B. 25 Hz
c. 50 нz
D. 100 нz
12
344 What is the conductivity of a
semiconductor if electron density ( = )
( 5 times 10^{12} / c m^{3} ) and hole density ( =8 times )
( mathbf{1 0}^{13} / mathbf{c m}^{3}left(boldsymbol{mu}_{e}=mathbf{2 . 3 m}^{2} boldsymbol{V}^{-1} boldsymbol{s}^{-1}, boldsymbol{mu}_{boldsymbol{h}}=right. )
( left.0.01 m^{2} V^{-1} s^{-1}right) )
( mathbf{A} cdot 5.634 )
B. 1.968
c. 3.421
D. 8.964
12
345 The output of a 2 -input OR gate is zero only when its
A. both inputs are 0 .
B. either input is 1.
c. both inputs are 1
D. either input is 0
12
346 13. The shows two NAND gates followed by a NOR gate.
The system is equivalent to the following logic gate
(a) OR
(c) NAND
(b) AND
(d) None of these
12
347 Zener diode is a voltage regulation device.
A . True
B. False
12
348 State whether True or False:
A semiconductor at absolute zero
become a insulator.
A. True
B. False
12
349 A change of ( 8 m A ) in the emitter current brings a change of ( 7.9 m A ) in the collector current. The value of ( alpha ) is
A. ( 80 / 79 )
B. ( 79 / 80 )
c. 79
D. 80
12
350 The energy gap in a semiconductor
A. Increases with temperature
B. Does not change with temperature
C . Decreases with temperature
D. Is zero
12
351 The transfer characteristics of a
transistor means a plot of
A. input voltage versus input current
B. output voltage versus output current
c. input voltage versus output voltage
D. input current versus output current
12
352 Three variable Boolean expression ( boldsymbol{P Q}+boldsymbol{P Q R}+overline{boldsymbol{P}} boldsymbol{Q}+boldsymbol{P} overline{boldsymbol{Q}} boldsymbol{R} operatorname{can} mathrm{be} )
written as
A. ( bar{Q}+bar{P} R )
в. ( bar{P}+bar{Q} R )
c. ( Q+P R )
D. ( Q+sqrt{P} R )
E . ( P+Q R )
12
353 Zener diode acts as a/an
A . oscillator
B. regulator
c. rectifier
D. fliter
12
354 Suppose a pure Si crystal has ( 5 times 10^{28} )
atoms ( m^{-3} . ) it is doped by 1 ppm
concentration of pentavalent As. Calculate the number of electrons and
holes. Given that ( n_{1}=1.5 times 10^{16} m^{-3} )
12
355 Fill in the blanks.
The traces of impurity added for doping are called
12
356 Assertion
A laser beam of ( 0.3 W ) can drill a hole
through metal sheet, whereas light of ( 1000 W ) can not do so
Reason
Laser beam has very high frequency
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
357 The circuit shown below contains two
diodes each with a forward resistance
of ( 50 Omega ) and
with infinite backward resistance. Find
the current through ( 150 Omega ) resistor.
A. zero
B. ( 0.01 A )
c. ( 0.02 A )
D. 0.03 A
12
358 In a N-P-N transistor about ( 10^{10} )
electrons enter the emitter in ( 2 mu s, ) when
it is connected to a battery. Then ( boldsymbol{I}_{boldsymbol{E}}= )
( boldsymbol{mu} boldsymbol{A} )
A . 200
в. 400
c. 800
D. 1600
12
359 Match the following
a) p-type
1) Pure semiconductor semiconductor
b) Intrinsic
2) Doped with impurity semiconductor
c) Extrinsic
3) majority carriers are semiconductor ( quad ) electrons
d) ( n ) -type
4) majority carriers are semiconductor holes
( A cdot a-3, b-2, c-4, d-1 )
B. ( a-1, b-2, c-4, d-3 )
C. ( a-4, b-1, c-2, d-3 )
D. ( a-2, b-1, c-4, d-3 )
12
360 In the middle of the depletion layer of a reverse-biased p-njunction, the
A. electric field is zero
B. potential is maximum
c. electric field is maximum
D. potential is zero
12
361 What happens when a p-njunction is
(a) forward biased
(b) reverse biased?
12
362 4. In a common base amplifier, the phase difference between
the input signal voltage and output voltage is
(b) 0
(c) r
(d) I
(AIEEE 2005)
12
363 Explain the working of a half wave diode
rectifier.
12
364 In ( n-p-n ) transistor circuit, the collector current is ( 5 mathrm{mA} ). If ( 98 % ) of electrons
emitted reach the collector then the
emitter current will be
A . ( 5.1 mathrm{mA} )
B. 8.1 mA
( c cdot 6.5 mathrm{mA} )
D. ( 10 mathrm{mA} )
12
365 To get an output ( y=1 ) from the circuit
shown, the inputs ( A, B ) and ( C ) must be respectively
A. 0,1,0
B. 1,0,0
c. 1,0,1
D. 1,1
12
366 Which are good conductors?
This question has multiple correct options
A. silicon
B. Silver
c. copper
D. glass
12
367 What is true for an ideal transistor
switch when turned OFF?
This question has multiple correct options
A. It has an infinite resistance
B. It has low resistance
c. It has maximum current flow
D. It has zero current flow
12
368 Diodes ( D-1 ) and ( D_{2} ) shown in circuit
are silicon diodes.The voltage drop (V)
across the diode ( D_{2} ) and the power
dissipated (P) by this diode ( left(D_{2}right) ) are
( mathbf{A} cdot V_{D_{2}}=0.7 V ) and ( P_{D_{2}}=0 W )
B. ( V_{D_{2}}=5 V ) and ( P_{D_{2}}=0 W )
( mathbf{C} cdot V_{D_{2}}=0.7 V ) and ( P_{D_{2}}=0.7 W )
D. ( V_{D_{2}}=5.0 V ) and ( P_{D_{2}}=5 W )
12
369 When NPN transistor is used as an
amplifier?
A. Electrons move from base to emitter
B. Electrons move from emitter to collector
c. Electrons moves from base to emitter
D. Holes moves from base to emitter
12
370 A semiconductor having electron and
hole mobilities ( mu_{n} ) and ( mu_{p} ) respectively.
if its intrinsic carrier density is ( n_{i}, ) then
what will be the value of hole
concentration ( P ) for which the
conductivity will be minimum at a
given temperature?
A ( cdot n_{i} sqrt{frac{mu_{n}}{mu_{p}}} )
В ( cdot n_{h} sqrt{frac{mu_{n}}{mu_{p}}} )
( mathbf{c} cdot n_{i} sqrt{frac{mu_{p}}{mu_{n}}} )
D. ( n_{h} sqrt{frac{mu_{p}}{mu_{n}}} )
12
371 Mention any four electronic gadgets. 12
372 Which logic gate corresponds to the truth table given below.
( begin{array}{lll}text { A } & text { в } & text { c } \ & & \ text { 0 } & text { o } & text { 1 } \ text { 0 } & text { 1 } & text { o } \ text { 1 } & text { 0 } & text { o } \ text { 1 } & text { 1 } & text { o }end{array} )
A. AND
в. NOR
( c . ) or
D. NAND
12
373 9. When on impurity is doped into an intrinsic semiconductor,
the conductivity of the semiconductor
(a) Increases
(b) Decreases
(c) Remains the same (d) Becomes zero
.
.
12
374 What is the use of a Zener diode? 12
375 What is the optimum band gap energy
for a material to be considered as a
semiconductor?
A. greater than ( 6 e V )
B. less than ( 6 e V )
c. ( 0 e V )
D. ( 0.5-3 e V )
12
376 From the following, reverse biased diode
is
( A )
в.
c.
D.
12
377 The change in emitter current by ( 2.1 mathrm{mA} ) results in change of ( 2 mathrm{mA} ) in the collector current and a change of ( 0.05 V ) in the emitter base voltage. The input resistance is
A . ( 5 K Omega )
в. зкл
c. 1 К ( Omega )
D. 0.5к.
12
378 An ( L E D ) is constructed from a pn
junction based on a certain semiconducting material whose energy gap is ( 1.9 e V . ) Then the wavelength of the emitted light is
A ( .2 .9 times 10^{-9} mathrm{m} )
в. ( 1.6 times 10^{-8} mathrm{m} )
c. ( 6.5 times 10^{-7} m )
D. ( 9.1 times 10^{-5} m )
12
379 In half wave rectifier, a p-n diode with internal resistance ( 20 Omega ) is used. If the
load resistance of ( 2 K Omega ) is used in the
circuit, then the efficiency of this half wave rectifier is (in percentage)
12
380 The valency of impurity element for making p-type semiconductor is
A . 5
B. 3
( c cdot 4 )
( D )
12
381 The impurity atoms, with which pure silicon should be doped to make a ptype semiconductor, are those of This question has multiple correct options
A. phosphorous
B. boron
C. antimony
D. aluminium
12
382 Which of the following is a correct
statement about current carrying
conductor?
A. On increasing temperature drifts speed of free electron decreases
B. On increasing temperature drift speed of free electron increases
C. On increasing temperature, drift speed of free electron remains same.
D. On increasing P.D. average kinetic energy of electron decreases ( Neglected heating effect of electric current)
12
383 The reverse breakdown voltage of a
Zener diode is ( 5.6 mathrm{V} ) in the given circuit
The current ( I_{Z} ) through the Zener is
( mathbf{A} cdot 7 m A )
В. 17 тА
( c .10 m A )
D. ( 15 mathrm{mA} )
12
384 The drift current in a p-njunction is
A. from the n-side to the p-side
B. from the p-side to the n-side
C. from the n-side to the p-side if the junction is forwardbiased and in the opposite direction if it is reverse biased
D. from the p-side to the n-side if the junction is forwardbiased and in the opposite direction if it is reversebiased
12
385 8. If the lattice constant of this semiconductor is decre
then which of the following is correct?
Conduction band gap T ITITIINIKE,
band gap
All
B
and E, in
Valence band gap ZIMATIZITZZZZE,
(a) All E., E., and E, decrease.
(b) All E., E, and E, increase.
(c) E, and E, increase, but E, decreases.
(d) E, and E, decrease, but E, increases.
(AIEEE 2006)
decreas
12
386 An oscillator is nothing but an amplifier
with
A. positive feedback
B. large gain
c. no feedback
D. negative feedback
12
387 Forbidden gap in a pure conductor is
A. 0 eV
B. 0.7 eV
c. ( 1.1 mathrm{eV} )
D. 6 eV
12
388 When the temperature changes, the
operating point is shifted due to
A. Change in ( I_{C B O} )
B. Change in ( V_{C C} )
C. Change in the values of circuit resistance
D. None of the above
12
389 Assertion
In some solids, the valence band is
completely filled while the next higher band separated by an energy gap of few electrons-volts is completely empty.
Reason
In insulators the energy band completely filled with electrons( the valence band) and above it is empty
band (the conduction band)
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
390 The charge carriers in a p-type
semiconductor are:
A. electrons only
B. holes only
C. holes in larger numbers and electrons in smaller numbers
D. holes and electrons in equal numbers
12
391 Carbon, silicon and germanium have
four valence electrons each. At room
temperature the appropriate statement
is
A. The number of free electrons for conduction is significant only in Si and Ge but small in ( mathrm{C} )
B. The number of free conduction electrons is significant in C but small si and Ge.
C. The number of free conduction electrons is negligibly small in all the three.
D. The number of free conduction electrons is significant in all the three.
12
392 In a photo-diode,
A. photocurrent is proportional to incident light intensity
B. photocurrent is inversely proportional to incident light intensity
C. photocurrent is independent of the incident light intensity
D. incident light intensity is proportional to the photocurrent
12
393 The material selected for solar cell
fabrication has
This question has multiple correct options
A. band gap (1.0 to 1.8 eV)
B. high optical absorption ( left(10^{4} mathrm{cm}^{-1}right) )
c. electrical conductivity
D. band gap (0.4 to 1. eV)
12
394 Match the following:
Left column lists the level of integration and right column lists the number of circuit components.
12
395 The magnitude of the force between a pair of conductors, each of length 110 ( mathrm{cm}, ) carrying a current of ( 10 mathrm{A} ) and separated by a distance of ( 10 mathrm{cm} ) is
A ( cdot 55 times 10^{-5} N )
B . ( 44 times 10^{-5} N )
c. ( 33 times 10^{-5} N )
D. ( 22 times 10^{-5} N )
12
396 If the collector current changes from ( 2 m A ) to ( 3 m A ) in a transistor when
collector – emitter voltage is increased from ( 2 V ) to ( 10 V ), the output
resistance is
( mathbf{A} cdot 1 K Omega )
B. ( 8 K Omega )
( mathbf{c} cdot 8 m Omega )
D. ( 1 mathrm{m} Omega )
12
397 A Ge specimen is doped with Al. The
concentration of acceptor atoms is ( sim ) ( 10^{21} ) atoms ( / m^{3} . ) Given that the intrinsic
concentration of electron-hole pairs is
( 10^{19} / m^{3} . ) The concentration of electrons in the specimen is:
( mathbf{A} cdot 10^{17} / m^{3} )
B . ( 10^{15} / m^{3} )
c. ( 10^{4} / m^{3} )
D. ( 10^{2} / m^{3} )
12
398 The intrinsic semiconductor behaves as
insulator at
( mathbf{A} cdot 0^{0} C )
B . ( 100^{circ} mathrm{C} )
c. ( 100 K )
D. ( 0 K )
12
399 When the p-njunction diode is reverse biased, the thickness of the depletion
layer
A . increases
B. decreases
c. becomes zero
D. remain constant
12
400 What is the state of an ideal diode in
the region of nonconduction?
A. Open circuit
B. Short circuit
c. undefined
D. None of the above
12
401 Why is a photodiode is used in reverse
bias?
A. Photocurrent flows only in reverse bias
B. Thermally generated current is large in reverse bias as compared to the photocurrent
C. Photocurrent is large in forward bias as compared to the forward bias current.
D. Photocurrent is significant in reverse bias as compared to the reverse bias current.
12
402 A light emitting diode (LED) has a voltage drop of ( 2 mathrm{V} ) across it and passes a current of 10 mA. When it operates with a ( 6 mathrm{V} ) battery through a limiting resistor ( R, ) the value of ( R ) is
A . ( 200 Omega )
B. 400 ( Omega )
c. ( 40 k Omega )
D. 4 ( k Omega )
12
403 84
10. Ge and Si diodes conduct at 0.3 V and 0.7 V, respectively.
In the following figure if Ge
diode connection are
reversed, the valve of V.
changes by
(a) 0.2 V
(b) 0.4 V
(c) 0.6 V
(d) 0.8 V
12 VI
> 522
12
404 The truth table given is for which gate?
( begin{array}{ccc}mathbf{A} & mathbf{B} & mathbf{Y} \ 0 & 0 & 1 \ 0 & 1 & 1 \ 1 & 0 & 1 \ 1 & 1 & 0end{array} )
( A cdot X O R )
B. OR
C . AND
D. NAND
12
405 In class A amplifiers, current through
load flows for
A. full cycle of the signal
B. half cycle of the signal
c. ( frac{1}{4} ) cycle of the signal
D. None of these
12
406 Consider the circuit, the current
through the Zener diode is
( A cdot 20 m A )
в. ( 10 mathrm{mA} )
( c .15 mathrm{mA} )
D. ( 40 mathrm{mA} )
12
407 In a p-njunction diode, not connected to
any circuit
A. the potential is same everywhere.
B. the p-type side is at a higher potential than the n-type side.
C. there is an electric field at the junction directed from the n-type side to the p-type side.
D. there is an electric field at the junction directed from the p-type side to the n-type side.
12
408 Draw the circuit diagram of full-wave rectifier using two p-njunction diodes and explain its working. Show the input
and output waveforms.
12
409 Figure shown a DC voltage regulator
circuit, with a Zener diode of breakdown
voltage ( =6 V . ) If the unregulated input
voltage varies between ( 10 V ) to ( 16 V )
then what is the maximum Zener
current?
A. ( 2.5 mathrm{mA} )
B. ( 3.5 mathrm{mA} )
c. ( 7.5 m A )
D. ( 1.5 mathrm{mA} )
12
410 Which logic gate is represented by the following combination of logic gates?
A. OR
в. NOR
( c cdot ) AND
D. NAND
12
411 Meeta’s father was driving her to the school. At the traffic signal she noticed
that each traffic light was made of many tiny lights instead of a single bulb. When meeta asked this question
to her father. he explained the reason for
this.
Answer the following based on above information:
(i) What were the values displayed by meeta and her father?
(ii) What answer did meeta’s father
give?
(iii) What are the tiny lights in traffic signals called and how do these
operate?
12
412 5. A semiconductor device is connected in a serried circuit
with a battery and a resistance. A current is found to pass
through the circuit. If the polarity of the battery is reversed,
the current drops almost to zero. The device may be
(a) Ap-type semiconductor
(b) An n-type semiconductor
(c) A p-n junction
(d) An intrinsic semiconductor
12
413 In forward bias, the depletion layer behaves like
A . an insulator
B. a conductor
c. a semiconductor
D. a capacitor
12
414 7. In the common base mode of a transistor, the collector
current is 5.488 mA for an emitter current of 5.60 mA. The
value of the base current amplification factor (B) will be
(a) 48
(b) 49
(c) 50
(d) 51 (AIEEE 2006)
12
415 When a p-njunction is reverse biased, the current becomes almost constant at
( 25 mu A . ) When it is forward biased at
( 200 m e V, ) a current of ( 75 mu A ) is obtained Find the magnitude of diffusion current when the diode is
(a) unbiased
reverse-biased at ( 200 m V ) and
forward-biased at ( 200 m V )
12
416 In a full wave rectifier circuit operating from ( 50 H z ) mains frequency, the
fundamental frequency in the ripple would be
( mathbf{A} cdot 25 H z )
B. ( 50 mathrm{Hz} )
c. ( 70.7 H z )
D. ( 100 H z )
12
417 For a transistor amplifier in common emitter configuration for load
impedance of ( 1 mathrm{k} Omegaleft(mathrm{h}_{f e}=50 text { and } mathrm{h}_{mathrm{o} e}=right. )
( 25 mu A / V ), the current gain is:
A. -5.2
B . -15.7
c. -24.8
D. -48.78
12
418 In the circuit diagram of zener diode as
shown in figure, when the value of ( V_{0} ) is
8 volt, the current through zener diode s
( i_{1} ) and when ( V_{0} ) is 16 volt, the
corresponding current is ( i_{2} . ) Find the
value of ( left(i_{2}-i_{1}right) . ) (Zener breakdown
voltage ( left.=V_{2}=6 Vright) )
A. zero
B. ( 5.0 mathrm{mA} )
C ( .1 .5 mathrm{mA} )
( mathbf{D} cdot 8 m A )
12
419 Zener diode is used as 12
420 Name two pentavalent impurities. 12
421 For one electron vacancy,
A. no holes are created
B. 1 hole is created
C. 2 holes are created
D. 4 holes are created
12
422 What is rectification? With relevant
circuit diagram and waveforms explain
the working of a P-N junction diode as a full-wave rectifier.
12
423 The value of ( alpha ) of a transistor is ( 0.9 . ) The
change in the collector current
corresponding to a change of 4 m ( A ) in
the base current in a common
emitter arrangement is
( mathbf{A} .36 mathrm{mA} )
в. 72 тА
( c .18 m A )
D. 54 m
12
424 Assertion
In a common-emitter amplfier, the load
resistance of the output circuit is 1000 times the load resistance of the input
circuit. If ( boldsymbol{alpha}=mathbf{0 . 9 8}, ) then voltage gain is
( 49 times 10^{3} )
Reason
( boldsymbol{alpha}=frac{beta}{1-beta}( ) symbols have their usual
meaning).
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
425 To make a p-njunction conducting
A. The value of forward bias should be more than the
barrier potenital
B. The value of forward bias should be less than the barrier potential
C. The value of revers bias should be more than the
barrier potential
D. The value of revers bias should be less than the barrier
potential
12
426 A pure germanium crystal at absolute zero is :
A. an insulator
B. a good conductor
c. a semiconductor
D. none of the above
12
427 A pnjunction is a/an
A. Bidirectional component
B. Unidirectional Component
C. Linear component
D. None of these
12
428 An intrinsic semiconductor is:
A. undoped
B. dopedd
c. can be undoped or doped
D. semi-doped
12
429 The potential barrier of a silicon junction diode is ( 0.7 V . ) If the thickness
of the depletion layer in it is ( 10^{-4} mathrm{cm} ) Then the intensity of electric field across the junction is
A ( cdot 7 times 10^{3} V / m )
в. ( 7 times 10^{5} V / m )
C ( .7 times 10^{-5} V / m )
D. ( 7 times 10^{-4} V / m )
12
430 According to Moore’s Law:
A. The memory capacity of a chip is constant.
B. The memory capacity of a chip doubles every one and a half-years.
C. The memory capacity of a chip increases by ten times every one and a half-years.
D. The memory capacity of chip decreases with time.
12
431 When PNjunction os forward biased the current in junction
A. Increase
B. decrease
c. remains same
D. None of these
12
432 What is ‘depletion region’ in a semi conductor diode? 12
433 1. A piece of copper and another of germanium are cooled
to 77 K. The resistance of
(a) each of them decreases.
(b) each of them increases.
(c) of Cu decreases and Ge increases.
(d) of Cu increases and Ge decreases. (AIEEE 2004)
12
434 The number 0 (zero) is required for
A. transistor
B. abacus
c. computer
D. calculator
12
435 A full wave rectifier along with the
output is shown in the given figure. The
contributions from the diode ( left(D_{2}right) ) are
( A cdot C )
B. A, C
( c cdot B, D )
D. ( A, B, C, D )
12
436 A p-n photodiode is manufactured from
a semiconductor with gap of ( 3.1 mathrm{eV} ) Which of the following wavelengths can be detected by it?
( A cdot 4000 hat{A} )
в. 3900 ,
( c cdot 4200 hat{A} )
D. Both (1) & (2)
12
437 The drift velocity of electrons in a conductor is :
A. Very small
B. Very large
c. Equal to the velocity of the tight
D. Varies with the conductor
12
438 Write the names of two important processes which occur on formation of
p-njunction. Define the ‘depletion region’ and ‘potential barrier’ in it.
12
439 Given above are four logic gate symbols.
Those for OR, NOR and NAND are
respectively
( A cdot a, d, c )
B. ( d, a, b )
( c cdot a, c, d )
( D cdot d, b, a )
12
440 In intrinsic semiconductor at room
temperature number of electrons and holes are:
A. Equal
B. zero
c. Unequal
D. Infinite
12
441 State whether true or false:
A bulb is used in place of LED to detect
weak currents.
A. True
B. False
12
442 Which of the following is/are correct about the direction of holes/electron?
This question has multiple correct options
A. Holes are moving along the direction of electric field.
B. Electrons are moving along the direction of electric field.
C. Electrons are moving against the direction of electric field.
D. None of the above
12
443 To a germanium sample, traces of gallium are added as an impurity. The resultant sample would behave like:
A. a conductor
B. a p-type semi-conductor
c. an n-type semi-conductor
D. an insulator
12
444 When plate voltage in diode valve is increased from ( 100 mathrm{V} ) to ( 150 mathrm{V} ). Then, plate
increases from ( 7.5 mathrm{mA} ) to ( 12 mathrm{mA} ), then dynamic plate resistance will be
( mathbf{A} cdot 10 k Omega )
B. ( 11 k Omega )
( mathbf{c} cdot 15 k Omega )
D. ( 11.1 k . Omega )
12
445 What is rectification? Explain the working of bridge rectifier. Draw the input and output signals. 12
446 The probability of electrons to be found
in the conduction band of an intrinsic
semiconductor at a finite temperature
A. decreases exponentially with increasing band gap
B. increases exponentially with increasing band gap
c. decreases with increasing temperature
D. is independent of the temperature and the band gap
12
447 When ( n-p-n ) transistor is used as an
amplifier:
A. electrons move from base to collector
B. holes moves from emitter to base
C. holes move from collector to base
D. holes move from base to emitter
12
448 Carbon, Silicon and Germanium atoms
have limn valence electrons each. Their
valence and conduction bands
are separated by energy band gaps
represented by ( left(boldsymbol{E}_{boldsymbol{g}}right)_{boldsymbol{c}},left(boldsymbol{E}_{boldsymbol{g}}right)_{boldsymbol{s i}} ) and ( left(boldsymbol{E}_{boldsymbol{g}}right)_{boldsymbol{G} boldsymbol{e}} )
respectively. Which one of the following relationship is true in their
case?
A ( cdotleft(E_{g}right)_{C}>left(E_{g}right)_{s i} )
B. ( left(E_{g}right)_{C}<left(E_{g}right)_{s i} )
( mathbf{c} cdotleft(E_{g}right)_{C}=left(E_{g}right)_{s i} )
D cdot ( left(E_{g}right)_{C}<left(E_{g}right)_{G e} )
12
449 Explain the use of P-N junction diode as
full wave rectifier on the basis of the
following points.
(i) Labelled circuit diagram
(ii) Working method
(iii) Graph between input and output potential with the variation of time.
12
450 State the properties and uses of a Junction Diode. 12
451 In the middle of the depletion layer of a reverse biased ( p-n ) junction, the
A. Potential is zero
B. Potential is maximum
c. Electric field is maximum
D. Electric field is zero
12
452 The mobility of free electrons is greater
than that of free holes because
A. they carry negative charge
B. they are light
C. their mutual collisions are less
D. they require low energy to continue their motion
12
453 000
following
12
454 A transistor is used in the common
emitter mode as an amplifier. Then
This question has multiple correct options
A. the base-emitter junction is forward-biased.
B. the base-emitter junction is reverse-biased.
C. the input signal is connected in series with the voltage applied to bias the base-emitter junction.
D. the input signal is connected in series with the voltage applied to bias the base-collector junction In p-type semiconductor ( n_{h}>n_{e} )
12
455 22
out
5. In the following common emitter configuration an NPN
transistor with current
gain B = 100 is used.
The output voltage of
the amplifier will be
(a) 10 mV
(b) 0.1 V
(c) 1.0 V
(d) 10 V
12
456 The conductivity of a semi conductor is:
This question has multiple correct options
A. Greater than the conductivity of metals.
B. Less than the conductivity of metals.
C. Equal to the conductivity of metals.
D. Intermediate between the conductivity of metals and insulators.
12
457 State whether given statement is True or False
A germanium crystal is doped with boron impurity
A. True
B. False
12
458 What are the functions of three regions
of a transistor?
12
459 76. An input voltage V; of 0.20 V is applied to an operational
amplifier connected as shown in the diagram.
What is the output voltage Vo?
+8.0 V
8.0 v 10 ks
2.0 k81
V = 0.20 V
(a) 0.20 V
(c) 0.80 V
(b) 1.2 V
(d) 8.0 V
12
460 What is the output Y in the following circuit when all the three inputs ( A, B, C )
are first 0 and then ( 1 ? )
A . 1,1
в. 0,1
( c .0,0 )
D. 1,0
12
461 The ( V ) -I characteristic of a diode is
shown in the figure. The ratio of forward
to reverse bias resistance is :
4.10
( 3 cdot 10^{-6} )
( c .1 )
0.10
12
462 6. If the ratio of concentration of electrons to that of holes
in a semiconductor is 7/5 and the ratio of currents is 7/4,
what is the ratio of their drift velocities?
(b) 5
noont
(c) 4
(d)
(AIEEE 2006)
12
463 Insulators are materials having an electrical conductivity equal to:
A. Between ( 10^{-8} mathrm{S} / mathrm{cm} ) to ( 10^{3} mathrm{S} / mathrm{cm} )
B. ( 10^{3} mathrm{S} / mathrm{cm} )
12
464 In the given circuit, the voltage across
the voltage across the load is
maintained at ( 12 mathrm{V} ). The current in the
zener diode varies from 0-50 mA. What
is the maximum watage of the diode?
( A cdot 12 W )
B. 6 w
c. ( 0.6 w )
D. ( 1.2 mathrm{w} )
12
465 We are familiar with the
semiconductors Silicon and
Germanium.
a) Draw the energy bands of a ( n ) -type semiconductor.
b) The following figure represents a
12
466 In the Boolean algebra, the following one
is wrong
A . ( 1.0=0 )
B. ( 0.1=0 )
c. ( 1.1=0 )
D. ( 1.1=1 )
12
467 The input resistance of a common emitter transistor amplifier, if the
output resistance is ( 500 mathrm{k} Omega ), the
current gain ( alpha=0.98 ) and the power
( operatorname{gain} ) is ( 6.0625 times 10^{6}, ) is
( mathbf{A} cdot 198 Omega )
в. 300Omega
c. ( 100 Omega )
D. ( 400 Omega )
12
468 Assertion
An ( n- ) type semiconductor has a large
number of electrons but still it is
electrically neutral
Reason
An ( n- ) type semicondutor is obtained
by doping an intrinsic semiconductor with a pentavalent impurity.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
469 (i) Define rectification.
(ii) Draw a circuit diagram of a full-
wave rectifier.
(iii) Semi-conductor related to given
energy band diagram is:
n-type semi-conductor, p-type semiconductor or intrinsic semi-conductor.
12
470 In a semiconductor, acceptor impurity is :
A. Antimony
B. Indium
c. Phosphorous
D. Arsenic
12
471 A potential barrier of ( 0.5 mathrm{V} ) exists across a p-njunction
(i) If the depletion region
is ( 5 times 10^{-7} ) m wide. What is the average
intensity of the eectric field in this
region?
(ii) An electron with speed ( 5 times )
( 10^{5} mathrm{m} / mathrm{s} ) approaches the ( mathrm{p} ) -n junction
from the n-side with what speed will it enter the p-side?
12
472 In the depletion layer of p-njunction diode, these are presents.
A. Only holes
B. Only electrons
c. Electrons and holes both
D. Neither electron nor hole
12
473 The rating of a zener diode is ( 1 W, 15 V ) Find the zener maximum current.
( mathbf{A} cdot 66.7 A )
в. ( 1 A )
( c .15 A )
D. ( 66.7 m A )
12
474 Consider a two-input AND gate of figure
below. Out of the four entries for the
Truth Table given here, the correct ones
are
( -1-1 ) begin{tabular}{|c|c|c|c|}
hline multirow{2}{*} {1} & A & B & C \
cline { 2 – 5 } & 0 & 1 & 0 \
cline { 2 – 4 } & 1 & 0 & 0 \
cline { 2 – 4 } 3 & 1 & 1 & 1 \
hline multirow{2}{*} {4} & 0 & 0 & 1 \
hline
end{tabular}
( mathbf{A} cdot ) Al
B. 1 and 2 only
C. 1,2 and 3 only
D. 1,3 and 4 only
12
475 The element that can be used as
acceptor impurity to dope silion is :
A. Antimony
B. Arsenic
c. Boron
D. Phosphorous
12
476 18. The current through an ideal P-N junction shown in the
following circuit diagram will be
re
10022
las
7 1
V
2
V 7
cm
(a) zero A ED
(c) 10 mAh
(b) 1 mA 100
(d) 30 mA
12
477 A p-njunction diode cannot be used
A. as a rectifier.
B. for converting light energy to electric energy.
C . for getting light radiation.
D. for increasing the amplitude of an AC signal.
12
478 A NOR gate and a NAND gate are connected as shown in the figure. Two different sets of inputs are given to this setup. In the first case, the inputs to the gates are ( boldsymbol{A}=mathbf{0}, boldsymbol{B}=mathbf{0}, boldsymbol{C}=mathbf{0} . ) In the
second case, the inputs are ( boldsymbol{A}=mathbf{1}, boldsymbol{B}= )
( 0, C=1 . ) The output ( D ) in the first case
and second case respectively are:
A. 0 and 0
B. 0 and 1
c. 1 and 0
D. 1 and 1
12
479 In n type semiconductor, electrons are
majority charge carriers but it does not show any negative charge. The reason is
A. Electrons are stationary
B. Electrons neutralize with holes
c. Mobility of electrons is extremely small
D. Atom is electrically neutral
12
480 If ( A=1 ) and ( B=0, ) than ( A . A+B ) in the
Boolean expression is equal to
A. ( B )
в.
c. ( A . B )
D. B.B
12
481 The peak voltage in the output of a halfwave diode rectifier fed with a
sinusoidal signal without filter is ( 10 mathrm{V} ) The d.c. component of the output voltage is
A. ( 10 / sqrt{2} V )
в. ( 10 / pi V )
( c cdot 10 v )
D. ( 20 / pi V )
12
482 begin{tabular}{|c|c|}
hline 0 \
( -5 mathrm{V} ) \
hline
end{tabular}
( 5 mathrm{V} )
0
0
( -10 mathrm{V} )
( 10 mathrm{V} )
( log _{10} 10 )
12
483 NAND and NOR gates are called universal gates primarily because they
A. are available universally
B. can be combined to produce OR, AND and NOT gates
c. are widely used in Integrated circuit packages
D. are easiest to manufacture
12
484 49. Which of the following gates corresponds to the truth table
given below?
Α.
IB
х
0
1 0 1
011
001
(a) XOR
(c) NAND
(b) OR
(d) NOR
JAN
12
485 A hole is
A. a positively charged electron.
B. an electron in the valence band.
C. an unfilled covalent bond.
D. an excess electron in covalent bond.
12
486 A PN-junction has a thickness of the order of :
A ( .1 g m )
B. ( 1 mathrm{mm} )
( mathrm{c} cdot 1 mu mathrm{m} )
D. ( 1 p ) m
12
487 Derive the expression for the voltage gain of a transistor amplifier in ( mathrm{CE} ) configuration terms of the load
resistance ( boldsymbol{R}_{boldsymbol{L}} ). current gain ( boldsymbol{beta}_{boldsymbol{a}} ) and input resistance. Explain why input and output voltages are in opposite phase.
12
488 The process of introducing impurities in small quantities into an intrinsic semiconductor is called Doping.
A. True
B. False
12
489 The junction diode shown in figure is
ideal. The current in the circuit is
A . ( 50 A )
в. ( 30 A )
( c .20 m A )
D. 30 ( m A )
12
490 Among the following, one statement is not correct when a junction diode is in forward bias
A. the width of depletion region decreases.
B. free electron on n- side will move towards the junction
c. holes on p-side move towards the junction
D. electrons on n-side and holes on p-side will move away from junction.
12
491 The energy gap in glass at room temperature is:
A. greater than that in a semiconductor
B. less than that in a good conductor
C . greater than that in a good conductor
D. both (A) and (C) are true
12
492 Which one of the following statements
is not correct in case of a
semiconductor?
A. Temperature coefficient of resistance is negative
B. Doping increases conductivity
c. At absolute zero temperature, it behaves like an conductor
D. Resistivity is in between that of a conductor and insulator
12
493 A Zener diode is connected to a battery
and a load as shown. The currents ( boldsymbol{I}, boldsymbol{I}_{boldsymbol{Z}} )
and ( I_{L} ) are respectively
( mathbf{A} cdot 12.5 m A, 5 m A, 7.5 m A )
B. ( 15 mathrm{mA}, 7.5 mathrm{mA}, 7.5 mathrm{mA} )
c. ( 15 mathrm{mA}, 7.5 mathrm{mA}, 5 mathrm{mA} )
D. ( 12.5 mathrm{mA}, 7.5 mathrm{mA}, 5 mathrm{mA} )
12
494 The thickness of depletion region is of the order of
A. ( 0.1 mu m )
в. ( 1 mu ) т
c. ( 0.1 m m )
D. ( 1 mathrm{mm} )
12
495 Which logic gate is represented by the following combination of logic gates:
A. OR
B. NAND
( c . ) AND
D. NOR
12
496 For transistor action which of the
following statements is correct?
This question has multiple correct options
A. Base, emitter and collector regions should have similar size and doping concentration.
B. The base region must be very thin and lightly doped.
C. The emitter junction is forward biased and collector junction is reverse biased.
D. Both emitter junction and collection junction are forward biased.
12
497 A potential barrier of ( 0.5 mathrm{V} ) exists
across a p-njjunction. If the width of depletion layer is ( 10^{-6} m ), then intensity
of electric field in this region will be
A ( .1 times 10^{6} V / m )
в. ( 5 times 10^{5} mathrm{V} / mathrm{m} )
c. ( 4 times 10^{4} V / m )
D. ( 2 times 10^{6} mathrm{V} / mathrm{m} )
12
498 Potential difference across depletion
regions
A. creates due to build up of space charge
B. limits further diffusion of electrons and holes across the depletion plane
c. should not be zero
D. both ( A ) and ( B )
12
499 The majority carriers in a p-type semiconductor are
A. Electrons
B. Holes
c. Both A and B
D. Impurities
12
500 The impurity atoms with which pure silicon may be doped to make it a ( mathrm{p} ) type semiconductor are those of Imore than one option may he correct] This question has multiple correct options
A. phosphorus
B. boron
C. antimony
D. aluminium
12
501 Draw separate energy band diagrams for conductors, semi-conductors and insulators and label each of them. 12
502 The part of a transistor which is heavily dopped to produce a large number of majority carriers is:
A. Base
B. Emitter
c. collector
D. None of these
12
503 In a common base transistor circuit, the
current gain is ( 0.98 . ) On changing the emitter current by ( 5.00 mathrm{mS} ), the change
in collector current is?
A. ( 0.196 mathrm{mA} )
B. ( 2.45 mathrm{mA} )
c. ( 4.9 mathrm{mA} )
D. ( 5.1 mathrm{m} ) A
12
504 An n-type and p-type silicon can be obtained by doping pure silicon with:
A. arsenic and phosphorous
B. indium and aluminium
c. phosphorous and indiumm
D. aluminium and boron
12
505 The n-side of the depletion layer of a p-n junction.
A. Always has same width as of the p-side
B. Has no bound charges
c. Is negatively charged
D. Is positively chargedd
12
506 The figure shows the input waveforms ( A )
and B for ‘AND’ gate.

Draw the output waveform and write the
truth table for this logic gate.

12
507 p-type crystal of p-njunction diode is
connected to a positive terminal of
battery and n-type crystal connected to
negative terminal of battery. Then
A. diode is forward biased.
B. diode is reversed biased.
C. potential barrier in depletion layer increases.
D. potential barrier in depletion layer remains unchanged.
12
508 LED glows even when a electric
current passes through it. Fill in the
blank.
( A ). weak
c. can’t predicted
D. none of the above
12
509 The relationship between band gap
energy and temperature can be described by
A. supersymmetric quantum mechanics
B. hyperuniformity.
c. phonons theory.
D. Varshni’s empirical expression
12
510 Pure ( S e ) at ( 300 K ) has equal electron ( left(n_{e}right) )
and hole ( left(n_{h}right) ) concentration of ( 1.5 times )
( 10^{6} m^{-3} . ) Doping by indium increases
( boldsymbol{n}_{boldsymbol{h}}=mathbf{4 . 5} times mathbf{1 0}^{mathbf{2 2}} boldsymbol{m}^{-mathbf{3}} . ) Calculate the
doped silicon.
12
511 A semiconductor is doped with a donor
İmpurity:
This question has multiple correct options
A. the hole concentration increases
B. the hole concentration decreases
C. the electron concentration increases
D. the electron concentration decreases
12
512 3. In the following circuit I, and I are respectively
2 k92
10 V
14 KOS 12 03
(a) 0,0
(c) 5 mA, 0
(b) 5 mA, 5 mA
(d) 0,5 mA
12
513 Write the two examples of acceptor
impurities
12
514 In forward bias of p-njunction, the potential barrier
A. increases
B. decreases
c. remains unchanged
D. becomes zero
12
515 A laser beam passes through the air
into a piece of plexiglass. Find out the possible change in property of the laser beam
A. The velocity decreases
B. The wavelength increases
c. The frequency decreases
D. The period decreases
E. None of the above is true
12
516 Which of the following cannot be used in electronic devices?
A. Aluminium gallium arsenide
B. Indium gallium arsenide
c. Gallium arsenide
D. Quasicrystals.
12
517 A p-n photodiode is made of a material with a band gap of ( 2.0 e V . ) The minimum
frequency of the radiation that can be
absorbed by the material is nearly:
( mathbf{A} cdot 10 times 10^{14} mathrm{Hz} )
B . ( 5 times 10^{14} mathrm{Hz} )
c. ( 1 times 10^{14} H z )
D. ( 20 times 10^{14} mathrm{Hz} )
12
518 When the maximum clock rate is
quoted for a logic family, it applies to a
A. Shift register
B. Flip-flop
c. counter
D. single logic gate
12
519 If the photo-diode is biased with a voltage larger than the specified maximum reverse bias, then:
A. the device may suffer breakdown
B. the device’s efficiency will increase
c. the device will become forward biased
D. none of the above
12
520 Which of the following is/are correct
regarding the working principle of LED?
This question has multiple correct options
A. When an electron makes a transition to the valance
band to fill up a hole in a p-njunction, it emits energy in the form of photon
B. The energy of this photon is equal to the energy gap between conducction band and valance band energy levels
C. Energy of a photon is the product of frequency of electromagnetic radiation (f) and Planck constant (h)
D. Both A and B
12
521 Using Nand twice of two inputs ( A & B ) will give:
A. AND
в. ов
c. It can not be done
D. None of these
12
522 uut 010 -11.-11.5=0.4 V
11. In the circuit shown in figure, the maximum output voltage
Vois
10 v H-
DD
N
2k12
T/2
0
+ Vo
2k 2
2 ks
(b) 5 V
(a) O V
(c) 10 V
12
523 ILLUSTRATION 31.7 Write the truth table for circuit given in
figure consisting of NOR gate and identify the logic operation
(OR, AND, NOT) which this circuit is performing.
BO
12
524 Minority carriers in a p-type
semiconductor are
( mathbf{A} cdot ) free electrons
B. holes
C. neither holes nor free electron
D. both holes and free electrons
12
525 Assertion
Most amplifiers use common emitter circuit configuration
Reason
Its input resistance is comparatively higher
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
526 In a semi-conducting material the
mobilities of electrons and holes are ( mu_{e} )
and ( mu_{h} ) respectively. Which of the following is true?
A ( cdot mu_{e}>mu_{h} )
в. ( mu_{e}0 )
12
527 A red LED emits light at0.1 watt uniformly around it. The amplitude of the electric field of the light at a
distance of ( 1 mathrm{m} ) from the diode is :
( mathbf{A} cdot 6 V / m )
в. ( 2.45 V / m )
c. ( 5.48 V / m )
D. ( 1.73 V / m )
12
528 What are the advantages of Integrated Circuits (IC) 12
529 24. A triode has a plate resistance of 10 k 2 and amplification
factor 24. If the input signal voltage is 0.4 V (r.m.s.), and
the load resistance is 10 k2, then, the output voltage
(r.m.s.) is
(a) 4.8 V
(b) 9.6 V
(c) 12.0 V
(d) none of these
12
530 Zener-diode is used in.
A. Amplification
B. Rectification
C. Oscillator in producing oscillations
D. Volatge regulation
12
531 What is the resistivity of a pure
semiconductor at absolute zero?
A. Zero
B. Infinity
C. Same as that of conductors at room temperature
D. Same as that of insulators at room temperature
12
532 A) Draw a typical illuminated ( boldsymbol{P}-boldsymbol{n} )
junction solar cell.
B) LED convert ( _{text {一一一一一一 }} ) energy to light.
12
533 In a semiconductor, which of the
following statement is correct?
A. At ( 0 K ), Si is a super conductor.
B. In a p-type semiconductor the acceptor level lies near the conduction band.
C. Each donor atom contributes one hole.
D. ( p-n ) junction is electrically neutral
12
534 Which gates are called universal gates? 12
535 In LED visible light is produced by
A. Gallium phosphide
B. Gallium arsenide
c. Germanium phosphide
D. silicon phosphide
12
536 Construct the circuit symbol of Zener
diode
12
537 In an intrinsic semiconductor, the Fermi
energy level is
A. nearer to valence band than conduction band.
B. equidistant from conduction band and valence band.
C. nearer to conduction band than valence band.
D. bisecting the conduction band
12
538 9. A diode is connected to 220 V
(rms) ac in series with a capacitor
220 V
as shown in figure. The voltage
across the capacitor is
(a) 220 V
(b) 110 V
(c) 311.1 V
(2) 220 V
12
539 The lead marked with the arrow is the
A . collector
B. base
c. emitter
D. cor
12
540 State True or False :
The n-type collector moves very little while p-type moves appreciably.
A. True
B. False
12
541 In a Zener regulated power supply of a
Zener diode with ( V_{2}=6 V ) is used for
regulation. The load current is to be ( 4 m A ) and the unregulated input is ( 10 V )
The value of series resistor ( boldsymbol{R}_{boldsymbol{S}} ) is
(Assume ( left.boldsymbol{I}_{z}=mathbf{5} boldsymbol{I}_{L}right) )
A. less than ( 5 Omega )
B. Infinite
c. greater than ( 100 Omega )
D. zero
12
542 When a p-njunction diode is connected
in forward bias its barrier potential
A. decreases and less current flows in the circuit
B. decreases and more current flows in the circuit
C. increases and more current flows in the circuit
D. decreases and no current flows in the circuit
12
543 Among the following, the wrong statement in the case of semiconductor
is:
A. Resistivity is in between that of a conductor and insulator
B. Temperature coefficient of resistance is negative
c. Doping increases conductivity.
D. At absolute zero temperature, it behaves like a conductor
12
544 The addition of pentavalent impurities
of the semiconductor.
A. brings no change to the conductivity
B. decreases the conductivity
c. increases the conductivity
D. reduces the formation of free electrons
12
545 The Wavelength of a LASER beam can be used as a standard of
A. time
B. temperature
c. angle
D. length
12
546 When a diode is heavily doped the
A. Zener voltage will be low
B. Avalanche voltage will be high
C. Depletion region will be thin
D. Leakage current will be low
12
547 The diode cannot be
A. the simplest of semiconductor devices.
B. having characteristics that closely match those of a simple switch
C. is a multi terminal device
D. none of the above
12
548 For the circuit show below, the current
through the zener diode is :
( A cdot 5 ) m
B. Zero
c. ( 14 mathrm{mA} )
( 0.9 mathrm{m} )
12
549 Amplifier may be
A. multi stage
B. single stage
( c . ) both (a) & (b)
D. None of these
12
550 p-njunction diode can be used as
A. amplifer
B. detector
c. oscillator
D. capacitor
12
551 Which of the following is not a rectifier
circuit?
4
3
( c )
. none of thes
12
552 Solar cells are made of :
A. silicon
B. germaniuminmmmmm
c. silver
D. aluminium
12
553 a germanium crystal with arsenic ( (Z= )
33). A second semi-conductor Y is made
by doping germanium with indium ( Z=49 ). The two are joined end to end
and connected to a battery as shown.
Which of the following statements is
correct-
A. ( x ) is ( p ) -type, ( Y ) is ( n ) -type and the junction is forward biased
B. ( x ) is ( n ) -type, ( Y ) is ( p ) -type and the junction is forward biased
c. ( x ) is ( p ) -type, ( Y ) is ( n ) -type and the junction is reverse biased
D. ( x ) is ( n ) -type, ( Y ) is ( p ) -type and the junction is reverse biased
12
554 In figure the input is across the
terminals ( A ) and ( C ) and the output is
across ( mathrm{B} ) and ( mathrm{D} ). Then the output is
A . zero
B. same as input
C. half wave rectifier
D. full wave rectifier
12
555 If ‘p’ region of a semi conductor is connected to negative and ‘n’ region to positive pole, it is said to be
A. directed biased
B. unbiased
c. forward biased
D. reverse biased
12
556 The input signal given to a a CE
amplifier having a voltage gain of 150 is ( V_{i}=2 cos left(15 t+frac{pi}{3}right) . ) The
corresponding output signal will be
A ( cdot 300 cos left(15 t+frac{4 pi}{3}right) )
B. ( 300 cos left(15 t+frac{pi}{3}right) )
c.
( 75 cos left(15 t+frac{2 pi}{3}right) )
D. ( 2 cos left(15 t+frac{5 pi}{6}right) )
12
557 What is meant by feedback? Derive an expression for voltage gain of an amplifier with negative feedback. 12
558 In a junction transistor the emitter, base and collector are made of
A. extrinsic semiconductors
B. intrinsic semiconductors
c. both A and B
D. metal.
12
559 Which of the following is a property of a Light Emitting Diode (LED)?
A. Low Threshold Voltage and High Reverse Breakdown Voltage
B. High Threshold Voltage and High Reverse Breakdown voltage
c. High Threshold Voltage and Low Reverse Breakdown Voltage
D. Low Threshold Voltage and Low Reverse Breakdown voltage
12
560 A pulse waveform has a high time of 8 ms and a pulse width of 32 ms. The duty cycle is
A . 25%
B. 50%
c. 1%
D. 100%
12
561 Which of these is the best description of
a Zener diode?
A. It is a constant voltage device.
B. It operates in the reverse region
c. It is a constant current device
D. It works in forward region
12
562 For a common emitter circuit amplifier, the load resistance of the output circuit is 500 times the resistance of the input. circuit. If ( alpha=0.98, ) then, current gain is
A . 0.98
B. 50
c. 98
D. 49
12
563 Which of the following is not a type of an
IC?
A. Analog IC
B. Digital IC
c. Mixed IC
D. compound IC
12
564 Materials which allow only larger currents to flow through them are
A. Insulators
B. Semi-conductors
c. conductors
D. Alloys
12
565 The probability of electrons to be found in the condition band of an intrinsic
semiconductor 6 at a finite
temperature.
A. Increases exponentially with increasing band gap
B. Decreases exponentially with increasing band gap
c. Decreases with increasing temperature
D. Is independent of the temperature and the band gar
12
566 A diode made of silicon has a barrier
potential of ( 0.7 ~ V ) and a current of
( 20 m A ) passes through the diode when
a battery of emf ( 3 V ) and a resistor
is connected to it. The power dissipated across the resistor and diode are
A. ( 0.046 mathrm{W}, 0.014 mathrm{W} )
в. ( 4.6 mathrm{W}, 0.14 mathrm{W} )
c. ( 0.46 W, 0.14 W )
D. ( 46 W, 14 W )
12
567 ( ln mu_{e} ) and ( mu_{h} ) are electron and hole
mobility. E be the applied electric field, the current density ( J ) for intristic semiconductor is equal to
( mathbf{A} cdot n_{i} eleft(mu_{e}+mu_{h}right) E )
B ( cdot n_{i} eleft(mu_{e}-mu_{h}right) E )
c. ( frac{n_{i} eleft(mu_{e}+mu_{h}right)}{E} )
D. ( frac{E}{n_{i} eleft(mu_{e}+mu_{n}right)} )
12
568 The level formed due to impurity atom,in the forbidden energy gap,very near to the valence band in a p-type
semiconductor is called
A. acceptor level
B. donor level
c. conduction level
D. forbidden level
12
569 One serious drawback of semi-
conductor devices is
A. they do not last for long time.
B. they are costly.
c. they cannot be used with high voltage.
D. they pollute the environment
12
570 When transistors are used in digital circuits they usually operate in
A. active region
B. breakdown region
c. linear region
D. saturation and cutoff regions
12
571 The energy gap in case of which of the following is less than ( 3 e V ? )
A. Aluminium
B. Iron
c. Germanium
D. copper
12
572 Tu Oy
LUL
16. Which one is in forward bias?
(d) None of these
12
573 The value of ( A . bar{A} ) in Boolean algebra is
( mathbf{A} cdot mathbf{0} )
B.
( c . A )
D. ( bar{A} )
12
574 Pure ( S i ) at ( 500 K ) has equal number of
electron ( left(boldsymbol{n}_{e}right) ) and hole ( left(boldsymbol{n}_{boldsymbol{h}}right) )
concentration of ( 1.5 times 10^{16} m^{-3} )
Doping by indium increases ( n_{h} ) to ( 4.5 times )
( 10^{22} m^{-3} . ) The doped semiconductor is
of
A ( cdot n ) -type with electron concentration ( n_{e}=5 times 10^{22} mathrm{m}^{-3} )
B . p-type with electron concentration ( n_{e}=2.5 times 10^{10} mathrm{m}^{-3} )
C . ( n ) -type with electron concentration ( n_{e}=2.5 times 10^{23} mathrm{m}^{-3} )
D. ( p ) -type having electron concentrations ( n_{e}=5 times ) ( 10^{9} m^{-3} )
12
575 The output of NOT gate when its input is
( mathbf{0} )
( A ). is 1
B. is 0
c. can be 0 or 1
D. is 0 and 1
12
576 The depletion region in a semiconductor diode is formed at the
A. thermonic emitter
B. junction
c. diode
D. forbidden zone
12
577 Solar cells are made up of:
A. conductors
B. insulators
c. semiconductors
D. superconductors
12
578 A Zener diode
A. has a high forward voltage rating
B. has a sharp breakdown at low reverse voltage
C. has a negative resistance
D. none of the above
12
579 The output of an OR gate is connected to both the inputs of a NAND gate. The combination will serve as:
A. AND gate
B. NOT gate
c. NAND gate
D. NOR gate
12
580 For transistor action, state which statements are true:
(1) Base, emitter and collector regions should have similar size and doping concentrations.
(2) The base region must be very thin and lightly doped.
(3) The emitter-base junction is forward
biased and base-collector junction is reverse biased
(4) Both the emitter-base junction as well as the base-collectorjunction are
forward biased
( A cdot(4) ) and (1)
B. (1) and (2)
c. (2) and (3)
( D cdot(3) ) and (4)
12
581 What is the reason to operate the
photodiodes in reverse bias?
A. fractional change due to the photo-effects on the majority carrier dominated forward bias current is more easily measurable than the fractional change in the reverse bias current.
B. reverse bias is more efficient than forward bias.
C. fractional change due to the photo-effects on the minority carrier dominated reverse bias current is more easily measurable than the fractional change in the forward bias current.
D. reverse bias configuration result in larger amount of current ( (operatorname{in} mu A) )
12
582 The light emitting diode (LED) is
A. a heavily doped p-n junction with no external bias
B. a heavily doped p-n junction with reverse bias
C. a heavily doped p-njunction with forward bias
D. a lightly doped p-n junction with no external bias
E . a lightly doped p-n junction with reverse bias
12
583 63. The circuit diagram (see the figure) shows a login
combination with the states outputs X, Y and Z given for
inputs P, Q, R and S at state 1 (i.e., high). When inputs P
and R change to state 0, (i.e., low) with inputs Q and still
at 1, the condition of output X, Y and Z changes to
P(1)
ANDH
9X(1)
Q(1)
Y(1)
NOR
Z(0)
R(1)
– NOR
NOR
NOT
NOT Horn
S(1)
I (a) I (6) I (6) I d o
x 1 1 0 1 0
IY Io Ti I 10
1 Z 0 1 1 0 1
12
584 For creating a ( boldsymbol{p}-boldsymbol{n} ) junction,
A. we take one slab of p-type semiconductor and physically join it to another n-type semiconductor
B. continuous contact at the atomic level is necessary.
C. two macroscopic smooth flat slabs can be used
D. None of these
12
585 There is a sudden increase in current in
zener diode is
A. Due to rupture of bonds
B. Resistance of deplection layer becomes less
c. Due to high doping
D. Due to less doping
12
586 State whether given statement is True or False

In p-njunction diode, the forward bias current is very small as compared to the reverse bias current.
A. True
B. False

12
587 An experiment is performed to
determine the ( I-V ) characteristics of
a Zener diode, which has a protective
resistance of ( R=100 Omega ), and a
maximum power of dissipation rating
of ( 1 W . ) The minimum voltage range of
the DC source in the circuit is
A. ( 0-24 V )
В. ( 0-5 V )
( begin{array}{ll}c-12 V & V \ V V & -0.12end{array}-12 )
D. ( 0-8 V )
12
588 Assertion
The various energy bands in a solid may or may not overlap depending on the structure of the solid.
Reason
If they do not overlap then the intervals between them represent energies which the electrons in the solid cannot have.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
589 When an impurity is doped into an intrinsic semiconductor, the
conductivity of the semiconductor
A . increases
B. decreases
c. remains the same
D. becomes zero
12
590 9. Which of the following is biased?
(a)
et 5 (6)
* 10
+sv than
(C) – 12 VKA
(d)
A
SR
6-10 V
(AIEEE 2006)
12
591 What are extrinsic semiconductors?
Write two differences between the two
types of extrinsic semiconductors.
12
592 A semi conductor device with both
active and passive electronic elements
diffused into a silicon water to form a
functional circuit is called.
A. Thin-film circuit
B. Integrated circuit
c. Hybrid-circuit
D. Thick-film circuit
12
593 In the circuit shown in figure, the diode
is ideal. The potential difference
between A and B is?
A. ( V / 4 )
B.
c. zero
D. ( V / 2 )
12
594 The gate for which output is high, if at least one input is low is
A. NAND
в. NOR
c. AND
D. or
12
595 If the input frequency of a full wave
rectifier is ( 50 H z ) ac. Its output frequency is
A. ( 50 H z ) pulsating dc
B. ( 100 H z ) pulsating do
c. ( 200 H z ) pulsating dc
D. ( 500 H z ) pulsating dc
12
596 Explain the term ‘doping’ 12
597 In reverse biasing
A. large amount of current flows
B. potential barrier across junction increases
C. depletion laver resistance increases
D. no current flows
12
598 A potential barrier of ( 0.3 mathrm{V} ) exists across
a p-njunction. An electron with speed
( 5 times 10^{5} m / s e c ) approaches this p-n
junction from n-side, what will be its speed on entering the p-side?
A ( .4 .8 times 10^{5} mathrm{m} / mathrm{sec} )
В. ( 3.8 times 10^{5} mathrm{m} / mathrm{sec} )
c. ( 5.8 times 10^{5} mathrm{m} / mathrm{sec} )
D. ( 6.8 times 10^{5} mathrm{m} / mathrm{sec} )
12
599 The slope of plate characteristic and mutual characteristic curves of a triode
value is ( 0.02 mathrm{mA} / mathrm{V} ) and ( 1 mathrm{mA} / mathrm{V} ). The
amplification factor of triode value is:
A ( .2 times 10^{8} )
B. 20
c. 50
D. 40
12
600 What is light emitting diode (LED)? Explain its working principle and state factors on which the colour of light emitted by it depends. 12
601 Which type of semi-conductor is formed
when a trivalent impurity is dopped in a pure semiconductor?
12
602 f the lattice constant of this
semiconductor is decreased, then
( mathbf{A} cdot ) all ( E_{c}, E_{g}, E_{v} ) increases
B. ( E_{c} ) and ( E_{v} ) increases, but ( E_{g} ) decreases
( mathrm{C} cdot E_{c} ) and ( E_{v} ) decreases, but ( E_{g} ) increases.
D. all ( E_{c}, E_{g}, E_{v} ) decreases.
12
603 Carbon, Silicone, and Germanium al
have the same number of electrons in
an outer most shell. Explain?
12
604 Which of the following is not an advantage of Integrated Circuits (ICs).
A. Extremely small in size
B. High power consumption
c. Low cost
D. Less weight
12
605 An npn transistor receives
voltage to the collector terminal and ( _{-}-_{-}-_{-}-_{-}- ) voltage to the base terminal for proper operation
A. positive, positive
B. positive, negative
c. negative, positive
D. negative, negative
12
606 a speparanationa
varies as follows.
( 1 / 1 )
What
1
( M )
12
607 The value of ( beta ) of a transistor is ( 19 . ) The
value of ( alpha ) will be
A . 0.93
B. 0.98
( c .0 .99 )
D. 0.95
12
608 The band gap for a pure semiconductor is ( 2.1 e V . ) The maximum wavelength of a
photon which is able to create a hole-
electron pair is nearly:
A. ( 600 n m )
B. 590 nm
c. 400 n ( m )
D. 200nm
12
609 The hole in a p-type semiconductor is
A. an electron deficiency
B. an electron excess
c. an atom deficiency
D. positive ion
12
610 The junction area is kept much larger in
a solar cell
A. for solar radiation to be incident because we are
interested in more power.
B. for solar radiation to be incident because we are interested in less power
C. for solar radiation to be properly reflected from the junction.
D. None of these.
12
611 Distinguish between ‘paramagnetic’ and ‘ferromagnetic’ substances. 12
612 Consider the following statements A and B identify the correct statement from the following.
A) The width of the depletion layer in a
p-njjunction diode increases in forward bias.
B) In an intrinsic semiconductor, the
Fermi energy level is exactly in the middle of the forbidden gap.
A. A is true and B is false.
B. Both A and B are false
c. A is false and B is true
D. Both A and B are true
12
613 53. The figure shows a combination of logic gates.
To what single gate is this combination equivalent?
(a) EX-NOR
(b) NOR
Input
(c) EX-OR
(d) OR
IL
Output
M
12
614 Energy band gap between valence band and conduction band for semiconductor
is:
A. approximately 1 ev
B. less than conductors
c. equal to conductors
D. more than insulator
12
615 What is the energy band gap of:
(i) silicon and
(ii) germanium
12
616 The following arrangement performs the logic function of ( _{-}-_{-}-_{-}-_{-} ) gate
All the gates present above are NAND
gate
( A cdot A N D )
B. OR
c. NAND
D. EXOR
12
617 The logic expression which is NOT true in Boolean algebra is
( mathbf{A} cdot[overline{1}+overline{1}] cdot 1=0 )
В. ( [overline{1}+0] .1=0 )
c. ( [overline{1}+0] . overline{1}=0 )
D. ( [1+1] .1=0 )
12
618 A zener diode voltage regulator
operated in the range ( 120-180 V )
produces a constant supply of ( 110 V )
and ( 250 m A ) to the load. If the
maximum current is to be equally
shared between the load and zener, then
the values of series resistance ( left(R_{S}right) ) and
load resistance ( left(R_{L}right) ) are:
( mathbf{A} cdot R_{L}=70 Omega ; R_{S}=280 Omega )
B . ( R_{L}=440 Omega ; R_{S}=140 Omega )
C ( . R_{L}=140 Omega ; R_{S}=440 Omega )
( mathbf{D} cdot R_{L}=280 Omega ; R_{S}=70 Omega )
12
619 Explain the working of P-Njunction
diode in forward and reverse biased
mode
12
620 A change of ( 8 m A ) in the emitter current brings a change of ( 7.9 m A ) in the collector current. The value of ( beta ) is
A. ( 79 / 80 )
в. ( 80 / 79 )
c. 79
D. 80
12
621 In an n-type semiconductor, the Fermi-
energy level lies:
A. in the forbidden energy gap nearer to the conduction band
B. in the forbidden energy gap nearer to the valence band
C. in the middle of forbidden energy gap
D. outside of the forbidden energy gap
12
622 In the circuit shown below, ( V_{A} ) and ( V_{B} )
are the potentials at ( A ) and ( B, R ) is the
equivalent resistance between A and B,
( S_{1} ) and ( S_{2} ) are switches, and the diodes
are idea
This question has multiple correct options
( mathbf{A} cdot ) if ( V_{A}>V_{B}, S_{1} ) is open and ( S_{2} ) is closed then ( R=8 Omega )
B. if ( V_{A}>V_{B}, S_{1} ) is closed and ( S_{2} ) is open then ( R=12.5 Omega )
C. if ( V_{A}>V_{B}, S_{1} ) is open and ( S_{2} ) is closed then ( R=12.5 Omega )
D. if ( V_{A}>V_{B}, S_{1} ) is closed and ( S_{2} ) is open then ( R=8 Omega )
12
623 A ( p ) -type semiconductor has acceptor levels 57 me ( V ) above the valance band.
The maximum wavelength of light required to create a hole is (Planck’s
constant ( left.h=6.6 times 10^{-34} J-sright) )
A ( .57 AA )
В. ( 57 times 10^{-3} dot{A} )
c. 217100 月
D . ( 11.61 times 10^{-33} dot{A} )
12
624 Among the following, one statement is not correct when a junction diode is in forward bias
A. the width of depletion region decreases.
B. free electron on n- side will move towards the junction
c. holes on p-side move towards the junction
D. electrons on n-side and holes on p-side will move away from junction.
12
625 For what value of ( A, B ) and ( C . ) The output
of ( Y=1 )
A. 001
B. 101
( c cdot 100 )
D. 010
12
626 Write the logic symbols and prepare the truth tables of the following gates.
(i) AND
(ii) NOR.
12
627 The truth table for expression is the given Boolean expression is
[
(A+B) cdot overline{(A cdot B)}=1
]
A. begin{tabular}{|c|c|c|}
hline( A ) & ( B ) & ( Y ) \
hline 1 & 0 & 0 \
1 & 1 & 1 \
0 & 1 & 0 \
1 & 0 & 0 \
hline
end{tabular}
в. begin{tabular}{|c|c|c|}
hline( A ) & ( B ) & ( Y ) \
hline 1 & 1 & 1 \
0 & 0 & 1 \
1 & 0 & 0 \
1 & 0 & 1 \
hline
end{tabular}
c. begin{tabular}{|c|c|c|}
hline( A ) & ( B ) & ( Y ) \
hline 0 & 0 & 1 \
1 & 0 & 0 \
0 & 1 & 0 \
1 & 1 & 0 \
hline
end{tabular}
D. begin{tabular}{|c|c|c|}
hline( A ) & ( B ) & ( Y ) \
hline 1 & 1 & 0 \
0 & 1 & 1 \
1 & 0 & 1 \
0 & 0 & 0 \
hline
end{tabular}
12
628 Person who use boolean algebra for describing the operation of logic gates first was
A . Boole
B. Shannon
c. schottky
D. zener
12
629 A Truth table is given below. The logic gate having following truth table is
( A quad B quad Y )
( begin{array}{lll}0 & 1 & 1end{array} )
( 0 quad 0 )
( 0 quad 1 quad 0 )
10
A. NAND gate
B. NOR gate
c. AND gate
D. OR gate
12
630 Write one main use of Zener diode. 12
631 When light shines on a ( boldsymbol{p}-boldsymbol{n} ) junction
diode, the current ( (I) v s . ) voltage ( (V) ) is observed as in the figure below:
In which quadrant(s) does the diode generate power, so that it can be used
as a solar cell?
A . Quad 1 only
c. Quad 4 only
D. Quad 1 and 4 onl
12
632 www
13. In the circuit shown, A and 40A
B represent two inputs and C
represents the output. The circuit Boat
represents
(a) NAND gate
(b) OR gate
(c) NOR gate
(d) AND gate
(AIEEE 2008)
12
633 In a full wave rectifier in which input
voltage is represented by ( V=V_{M} sin omega t )
then peak inversion voltage of non conducting diode will be?
A. ( -V_{M} )
B. ( V_{M} / 2 )
с. ( 2 V_{M} )
D. 0
12
634 In common base circuit of a transistor,
current amplification factor is 0.95 Calculate the emitter current if base
current is ( 0.2 mathrm{mA} )
A . ( 2 mathrm{mA} )
B. ( 4 mathrm{m} )
( c .6 m A )
D. ( 8 mathrm{m} )
12
635 A capacitor is to be provide smoothing
for a half wave rectifier. In which of the
following diagrams is capacitor correctly connected?
( A )
B.
( c )
( D )
12
636 The current gain ( (beta) ) of a transistor in
common base mode is ( 40 . ) To change
the collector current by ( 160 mathrm{mA} ), the necessary change in the base current is
(at constant ( mathbf{V}_{C E} ) )
A. ( 0.25 mu )
B. ( 4 mu ) A
( c cdot 4 m A )
D. ( 40 mathrm{mA} )
12
637 20
18. The 1-V characteristic of an LED is
(b)
oooo
Red
Yellow
Green
Blud
(R) (Y) (G)(B)
(JEE Main 2013)
12
638 The working transistor with its three legs marked ( mathrm{P}, mathrm{Q}, ) and ( mathrm{R} ) is tested using a
multimeter. No conduction is found
between ( P & Q . ) By connecting the common (negative) terminal of the
multimeter to ( mathrm{R} ) and the other
(positive) terminal to ( mathrm{P} ) or ( mathrm{Q}, ) some
resistance is seen on the multimeter.
The correct statement for the transistor
is
A. It is an n-p-n transistor with ( mathrm{R} ) as base
B. It is a p-n-p transistor with ( mathrm{R} ) as collector
C. It is a p-n-p transistor with ( R ) as emitter
D. It is an n-p-n transistor with ( mathrm{R} ) as collector
12
639 The outputs of two NOT gates are fed to
a NOR gate. Draw the logic circuit of the combination of gates. Give its truth
table. Identify the gate represented by this combination.
12
640 The follwoing combined logic gate diagram is eqivalent to
A. NOR gate
B. oR gate
c. AND gate
D. NAND gate
12
641 In an intrinsic semiconductor,
conductivity is due to
A. doping
B. breaking of covalent bonds
c. free electrons
D. holes
12
642 What is biasing a diode? Write two differences between the two kinds of
biasing.
12
643 In a circuit shown in the value of ( beta ) is
100. ( I_{c}=1.5 m A . ) The transistor is in
A. Active state
B. Cut off state
c. Saturation state
D. Breakdown state
12
644 A Ge specimen is doped with ( A l ). The
concentration of acceptor atoms is ( sim ) ( 10^{21} ) atoms ( / m^{3} . ) Given that the intrinsic
concentration of electron-hole pairs is ( sim 10^{19} / m^{3}, ) the concentration of
electrons in the specimen is
( mathbf{A} cdot 10^{17} / m^{3} )
B . ( 10^{15} / m^{3} )
c. ( 10^{4} / m^{3} )
D. ( 10^{2} / m^{3} )
12
645 The Base-Emitter voltage for a CE
transistor used as an amplifier is ( 0.02 mathrm{V} ) An input signal given to this transistor results in a change of base current by, ( 20 mu A ) and a changes of ( 2 mathrm{mA} ) takes
place in the collector current. Calculate the following quantities:
1. Input resistance.
2. A.C. current gain
3. Transconductance.
4. If the load resistance is ( 5 k Omega ) what will
be the voltage gain.
12
646 To obtain a good quality DC from AC we
shall use
This question has multiple correct options
A . RC filter
B. LC filter
c. ( pi ) filter
D. Butterworth filter
12
647 Which of the following is the correct graph showing ( boldsymbol{V}-boldsymbol{I} ) characteristics
for an ideal ( P N ) junction diode?
12
648 In a transistor
A. the emitter has the least concentration of impurity
B. the collector has the least concentration of impurity
C. the base has the least concentration of impurity
D. all the three regions have equal concentrations of impurity
12
649 The current in the given circuit is:
(Given barrier potential of the diode =
( 0.5 V) )
( mathbf{A} cdot 4 m A )
B. ( 4 A )
c. ( 4 mu A )
D. ( 40 mu A )
12
650 An unknown transistor needs to be
identified as a ( n p n ) or ( p n p ) type.
multimeter, with ( + )ve and -ve
terminals, is used to measure resistance between different terminals
of transistor. If terminal 2 is the base of
the transistor then which of the
following is correct for a ( p n p ) transistor?
A. ( + )ve terminal
( 1,-v e ) terminal
2 , resistance high
( 2,-v e ) terminal
B. ( + )ve terminal
( 3, ) resistance low
c. ( + )ve terminal
( 3,-v e ) terminal
2 , resistance high
D. ( + )ve terminal ( 2, ) -ve terminal ( 1, ) resistance high
12
651 If ( N^{A} ) is number density of acceptor
atoms added and ( N^{D} ) is number
density of donor atoms added to a
semiconductor, ( n^{e} ) and ( n^{n} ) are the
number density of electrons and holes in it,then
A ( cdot n^{e}=N^{D}, n^{n}=N^{A} )
B . ( n^{e}=N^{A}, n^{h}=N^{D} )
c. ( N^{A}+n^{n}=N^{D}+n^{text {ศ }} )
D. ( n^{e}+N^{A}=n^{n}+N^{D} )
12
652 The depletion region is
A. region of opposite charges.
B. neutral region.
C . region of infinite energy.
D. region free of charge carriers.
12
653 Fermi energy level for ( boldsymbol{p}- )type extrinsic semiconductors lies
A . At middle of the band gap
B. close to conduction band
c. close to valence band
D. None of the above
12
654 The most widely used semiconductors
are
(i) silicon
(ii) germanium
(iii) phosphorus (iv) arsenic
A ( cdot ) (i) and (ii)
B. (ii) and (iii)
c. (iii) and (iv)
D. (i), (ii), (iv) (iii)
12
655 In the circuit shown, the diodes are
ideal. ( A_{1} ) and ( A_{2} ) are ammeters of
resistance ( 5 Omega ) each. The potentials of
the points ( A, B, C ) and ( D ) are ( V_{A}, V_{B}, V_{C} )
and ( V_{D} ) respectively. ( left|boldsymbol{V}_{boldsymbol{A}}-boldsymbol{V}_{boldsymbol{B}}right|=mathbf{1 0} boldsymbol{V} )
This question has multiple correct options
A. ( A_{1} ) and ( A_{2} ) will always show the same reading
B. the readings of ( A_{1} ) and ( A_{2} ) will depend on whether ( V_{A}>V_{B} ) or ( V_{A}V_{B}, A_{1} ) will show no deflection
12
656 Two similar p-njunctions can be connected in three different ways as
shown in the figures. The two connections across which the potential
difference is same are
( a) )
( b) )
( c )
A. circuits a and b
B. circuits b and c
C. circuits a and c
D. all the circuits
12
657 A semiconductor has an electron
concentration of ( 8 times 10^{13} ) per ( c m^{3} ) and ( a )
hole concentration of ( 5 times 10^{12} ) per ( c m^{3} )
The electron mobility is ( 25000 c m^{2} V^{-1} s^{-1} ) and the hole mobility
is ( 100 mathrm{cm}^{2} V^{-1} s^{-1} . ) Then
A. The semiconductor is ( n ) -type
B. The conductivity is 320 ( mathrm{m} ) mho ( mathrm{cm}^{-1} )
c. Both (a) and (b)
D. None of the above
12
658 A man wants to measure current ( sim boldsymbol{m} boldsymbol{A} )
He should use
A. photo multiplier tube
B. photo cell and amplifier
c. photo multiplier tube and amplifier
D. photo cell and two stage amplifier
12
659 The valency of impurity element for making n-type semiconductor is
A . 3
B. 5
( c cdot 4 )
( D )
12
660 A transistor is a two junction and two terminal device
A. True
B. False
12
661 The transfer ratio ( beta ) of a transistor is 50 The input resistance of the transistor
when used in the common emitter
mode is ( 1 K omega ).The peak value of the
collector alternating current for an
input peak voltage of ( 0.01 V ) is
A. ( 100 mu A )
в. ( 500 mu A )
c. ( 0.01 mu A )
D. ( 0.25 mu A )
12
662 If a rod has resistance 4 ohm and if rod
is turned as half circle, then the
resistance along diameter is
A. 1.56 ohm
B. 2.44 ohm
c. 4 ohm
D. 2 ohm
12
663 Direction of electric field in P-N junction
diode is
A. from P-side to N-side
B. from N-side to P-side
c. randomly oriented
D. electric field does not exist
12
664 In a current voltage plot of a ( mathrm{p}-mathrm{n} )
junction, find out the correct statement
from the following?
A. A p-njunction is essentially nonconducting when it is forward biased and highly conducting when it is reverse biased
B. A p-njunction is highly conducting when it is forward biased and essentially nonconducting when it is reverse biased
C. A p-njunction is highly conducting when it is forward biased as well as when it is reverse biased
D. A p-njunction is essectially nonconducting when it is forward biased as well as when it is reverse biased
12
665 Construct the logic symbol, Boolean expression, circuit diagram and truth
table for an OR gate.
12
666 Assertion
STATEMENT-1: If output of a AND gate is fed to OR gate, it is called NOR gate.
Reason
STATEMENT-2: If output of a AND gate is fed to NOT gate, it is called NAND gate.
A. Statement-1 is True, Statement-2 is True; Statementis a correct explanation for Statement-
B. Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement-
c. statement-1 is True, Statement-2 is False
D. Statement-1 is False, Statement-2 is True
12
667 In a transistor, forward bias is always
smaller than the reverse bias. This is
done to :
A. Maintain constant current supply
B. get good output
c. Avoid excessive heating of transistor
D. Maintain flow of majority charge carriers
12
668 With reference to semiconductor
devices, define a p-type semiconductor
and a Zener diode. What is the use of a
Zener diode?
12
669 Find the minimum load resistance
which can be used for the zener diode
as shown in figure. Given, ( boldsymbol{V}_{boldsymbol{Z}}= )
( mathbf{1 0} boldsymbol{V}, boldsymbol{R}_{Z}=mathbf{0} mathbf{Omega}, boldsymbol{R}=mathbf{4 5 0 Omega}, boldsymbol{I}_{Z}(boldsymbol{m} boldsymbol{i n})= )
( 2 m A ) and ( I_{Z}(max )=60 m A )
A . ( 0 Omega )
B. ( 333.3 Omega )
c. ( 31.95 Omega )
D. ( 319.5 Omega )
12
670 The vacancy created due to the absence
of an electron in the valence band of a
semiconductor is called a
A . electron
B. hole
c. proton
D. position
12
671 The following circut represents
A. OR gate
B. XOR gate
C. AND gate
D. NAND gate
12
672 To make a p-type semiconductor, an intrinsic semiconductor is doped with
A. Gallium or indium
B. Arsenic or phosphorus
c. Aluminium or boron
D. Both (1) and (3)
12
673 Write a short note on P-type semiconductor 12
674 Which of the following statement is not
true?
A. The resistance of intrinsic semiconductors decreases with increase to temperature
B. Doping pure Si with trivalent impurities gives p-type semiconductor
c. The majority carriers in n-type semiconductors are holes
D. A p-njunction can act as a semiconductor diode
12
675 Find the output ( F ) of the logic circuit
given below
12
676 Heavily doped p-n junction diode which emits light when it is forward biased is/are:
A. zener diode
B. photo-diode
c. light emitting diode
D. all of the above
12
677 Name the gate, which represents the Boolean expression ( boldsymbol{Y}=boldsymbol{A} cdot boldsymbol{B} )
A. NAND
B. AND
c. Not
D. NOR
12
678 An intrinsic semiconductor has
( 10^{18} / m^{3} ) free electron and is doped with
pentavalent impurity of ( 10^{24} / m^{3} . ) Then the free electrons density order increase by
A .4
B. 3
c. 5
D. 6
12
679 What is the type of the semiconductor,
for the energy band diagram shown in
the figure?
A. N-type semiconductor
B. P-type semiconductor
c. Intrinsic semiconductor
D. Both ( N ) and ( P ) type semiconductors
12
680 The forbidden gap for a pure silicon at the room temperature is eV.
A. Less than one
B. 1.1
( c cdot 3 )
D.
12
681 The barrier potential of a p-njunction depends on:
(a) type of semi conductor material
(b) amount of doping
(c) temperature
Which one of the following is correct?
A. (a) and (b) only
B. (b) only
c. (b) and (c) only
D. (a), (b) and (c)
12
682 In an unbiased ( p-n ) junction
A. Potential at ( p ) is more than that at ( n )
B. Potential at ( p ) is less than that at ( n )
C. Potential at ( p ) is equal to that at ( n )
D. Potential at ( p ) is +ve and that at ( n ) is -ve
12
683 Draw the logic symbol of AND gate. 12
684 An n-p-n transistor conducts when
A. both collector and emitter are positive with respect to the base.
B. collector is positive and emitter is negative with respect to the base.
C . collector is positive and emitter is at same potential as the base.
D. both collector and emitter are negative with respect to the base.
12
685 The output of OR gate is 1:
A. If either one or both inputs are 1
B. Only if both inputs are 1
C. If either input is zero
D. If both inputs are zero
12
686 Which of the following sources gives best monochromic light?
A. A candle
B. A bulb
c. A mercury tube
D. A laser
12
687 Figure shows the circuit of an electronic
device
(i) Which electronic device: a rectifier,
an amplifier or an oscillator does the
circuit represent?
(ii) State where the input voltage is
applied and where the output voltage is
available.
(iii) Compare the output voltage of this circuit with its input voltage.
12
688 With the help of circuit diagram, explain the V-1 characteristics of p-n junction diode in forward biasing. 12
689 What is the energy band gap of silicon and germanium respectively in ( e V ) ?
A . 1.1,0.7
в. 0.7,1.1
c. -0.7,-1.1
D. -1.1,-0.7
12
690 Calculate the mutual conductance ( g_{m} )
of the triode valve?
A ( .5 .33 times 10^{-3} mathrm{ohm}^{-1} )
B. ( 53.3 times 10^{-3} ) ohm ( ^{-1} )
c. ( 4.32 times 10^{-3} mathrm{ohm}^{-1} )
D. ( 5.00 times 10^{-3} mathrm{ohm}^{-1} )
12
691 A pure germanium crystal at absolute zero is:
A. An insulator.
B. A good conductor.
c. A semiconductor
D. None of the above
12
692 Which logic gate is represented by the following logic gates?
A. NOR
B. NAND
( c . ) AND
D. on
12
693 The necessary condition in making of a junction transistor (E-emitter, B-base
and C-collector)
A. ( E ) is heavily doped, ( B ) is thin and lightly doped and ( C ) is moderately doped
B. E and C are lightly doped and B is thick and heavily doped
C. ( mathrm{E} ) and ( mathrm{B} ) are heavily doped and ( mathrm{C} ) is lightly doped
D. ( mathrm{E} ) and ( mathrm{B} ) are lightly doped an ( mathrm{C} ) is heavily doped
12
694 W onductor
Which of the energy band diagrams shown in the figure
corresponds to that of a semiconductor?
СВ
(a)
(b)
VB
VB
СВ
СВ
E>>
T VB
E. = KT
VB
16
Two PN iunctions can be connen
12
695 For the given circuit shown in fig to act as full wave rectifier – ac input should
be connected across and ( ldots ldots . ) the d.c.
output would appear across ……… and
( A cdot A, C, B, D )
( B . B, D, A, C )
( mathbf{c} cdot A, B, C, D )
( D cdot C, A, D, B )
12
696 Barrier potential of a p-njunction diode does not depend on:
A. Diode design
B. Doping density
c. Temperature
D. Forward bias
12
697 An n-p-n transistor power amplifier in ( mathrm{C} ) E configuration gives
A. Voltage amplification only
B. Current amplification only
c. Both current and voltage amplification
D. only power gain of unity
12
698 In a semiconductor at room
temperature
A. the valence band is partially empty and the conduction band is partially filled.
B. the valence band is completely empty and the conduction band is partially filled.
C. the valence band is completely filled.
D. the conduction band is completely empty.
12
699 Explain with the help of a circuit diagram the working of a photo diode. Write briefly how it is used to detect the optical signals. 12
700 Which part in the diagram shows band
gap
A.
B. A
( c . ) в
D. A and C
12
701 ( dots )
the function ( Z ) of ( X ) and ( Y ) represented by
given figure is :
( A )
begin{tabular}{|c|c|c|}
hline( X ) & ( Y ) & ( Z ) \
hline 0 & 0 & 0 \
0 & 1 & 0 \
1 & 0 & 1 \
1 & 1 & 1 \
hline
end{tabular}
B. begin{tabular}{|c|c|c|}
hline( X ) & ( Y ) & ( Z ) \
hline 0 & 0 & 1 \
0 & 1 & 1 \
1 & 0 & 0 \
1 & 1 & 0 \
hline
end{tabular}
( c )
begin{tabular}{|c|c|c|}
hline( X ) & ( Y ) & ( Z ) \
hline 0 & 0 & 1 \
0 & 1 & 0 \
1 & 0 & 1 \
1 & 1 & 0 \
hline
end{tabular}
D. None of these
12
702 In the depletion region of an unbiased ( mathrm{P} )
Njunction diode there are
12
703 Explain the working of a diode as a half wave rectifier. 12
704 29. In a transistor circuit shown here
the base current is 35 uA. The
value of the resistor Rg is
(a) 123.5 k12
(b) 257 k 2
(c) 380.05 k 2
(d) None of these
R
R,
9V
12
705 Which type of gate the following truth
table represents?
( begin{array}{lll}text { Input } & text { Input } & text { Output } \ A & B & Q \ 0 & 0 & 1 \ 0 & 1 & 1 \ 1 & 0 & 1 \ 1 & 1 & 0end{array} )
( mathbf{A} cdot ) NOT
B. AND
( c cdot ) OR
D. NAND
12
706 Select the output ( Y ) of the combination
of gates shown in figure for inputs ( boldsymbol{A}= )
( mathbf{1}, boldsymbol{B}=mathbf{0} ; boldsymbol{A}=mathbf{1}, boldsymbol{B}=mathbf{1} ) and ( boldsymbol{A}=mathbf{0}, boldsymbol{B}= )
respectively.
A ( .(0,1,1) )
в. (1,0,1)
c. (1,1,1)
D. (1,0,0)
12
707 2. Electrical conductivity of a semiconductor
(a) Decreases with the rise in its temperature
(b) Increases with the rise in its temperature
(c) Does not change with the rise in its temperature
(d) First increases and then decreases with the rise in its
temperature
12
708 Fill in the blank.
In a Ruby laser, the colour of laser light is due to
A. Oxygen
B. Aluminium
c. xenon
D. Chromium
12
709 Electrical conduction in a
semiconductor takes place due to
A. electrons only
B. holes only
c. both electrons and holes
D. neither electrons nor holes
12
710 Vuuput LUI Siligie uute mpul gale is that of AND gate.
14. The diagram of a logic circuit is given below. The output
F of the circuit is represented by
Wo
of destin
wo
myam
(a) W (X+Y)
(c) W + (XY)

(b) W.(
X Y)
(d) W+ (X+Y)
12
711 Mention important characteristics and applications of a diode. 12
712 57. What is the output in the figure?
A Do
A
.
(a) A B
(b) A.
B
e
(c)
A.B
(d) A.B.
12
713 The following is NOT equal to 0 in the
Boolean algebra is
( mathbf{A} cdot overline{bar{A} cdot 0} )
в. ( A . bar{A} )
c. ( A . )
D. ( overline{A+bar{A}} )
12
714 In the Boolean algebra: ( boldsymbol{A}+boldsymbol{B} ) is equal
to:
( A cdot A+B )
B. ( bar{A}+bar{B} )
c. ( overline{A . B} )
D. ( bar{A} . bar{B} )
12
715 The use of zener diode is as 12
716 (a) A student wants to use two ( p-n )
junction diodes to convert alternating current into direct current. Draw the
labelled circuit diagram she would use and explain how it works.
(b) Give the truth table and circuit
symbol for NAND gate.
12
717 The ( beta ) of a transistor is ( 74 . ) It is connected in common base configuration. If the emitter current is
( 5 m A, ) the collector current is
(approximately)
A. ( 0.45 mathrm{mA} )
B. ( 4.93 mathrm{mA} )
( mathbf{c} .370 mathrm{mA} )
D. ( 5 m A )
12
718 State True or False:
n-p-n transistors exhibit higher transconductance and speed than ( mathrm{p}-mathrm{n}-mathrm{p} )
transistors.
A. True
B. False
12
719 For a transistor to work as an amplifier:
A. its emitter junction is in reverse bias and collector junction is in forward bias
B. the transistor must have breakdown region
C. its emitter junction is in forward bias and collector junction is in reverse bias
D. its emitter and collector junction are in forward bias
12
720 NOR gate is the series combination of
A. NOT gate followed by OR gate.
B. OR gate followed by NOT gate.
C. AND gate followed by OR gate.
D. OR gate followed by AND gate.
12
721 Assertion
The energy bands in a solid correspond to the energy levels in an atom.
Reason
An electron in a solid can have only
energies that fall with these energy
bands.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
722 If ( n_{p} ) and ( n_{e} ) are the number of holes and
conduction electrons in an intrinsic
semiconductor then
A ( cdot n_{p}>n_{e} )
в. ( n_{p}=n_{e} )
c. ( n_{p}<n_{e} )
D ( cdot n_{p} neq n_{e} )
12
723 Identify the electronic components from
the following symbols.

Write any one difference between them.
( mathbf{a} )

12
724 The input characteristics of a transistor
in ( C E ) mode is the graph obtained by
plotting
( mathbf{A} cdot I_{B} ) against ( V_{B E} ) at constant ( V_{C E} )
B. ( I_{B} ) against ( V_{C E} ) at constant ( V_{B E} )
C ( cdot I_{B} ) against ( I_{C} ) at constant ( V_{C E} )
D. ( I_{V} ) against ( I_{C} ) at constant ( V_{B E} )
12
725 A photoelectric cell emits electrons when illuminated by a ( 60 ~ W ) bulb. If the same cell is illuminated by replacing it with a ( 40 W ) bulb, the observation that can be made is
A. No photoelectric effect takes place
B. Number of photoelectrons increases
c. The kinetic energy of photoelectrons decreases
D. Number of photoelectrons decreases
12
726 In a p-type semiconductor, the electron current is ( _{-}-_{-}-_{-}- ) the hole current.
A. equal to
B. less than
c. greater than
D. none of the above
12
727 The maximum wavelength of photons that can be detected by a photo-diode, which is made of a semiconductor of
band gap ( 2 e V ) is about :
( mathbf{A} cdot 620 n m )
B. 700 nm
( c .740 n m )
D. ( 860 n m )
E. ( 1240 n m )
12
728 In the half wave rectifier circuit
operating from ( 50 H z ) mains frequency, the fundamental frequency in the ripple would be
( mathbf{A} cdot 25 H z )
B. ( 50 mathrm{Hz} )
c. ( 70.7 H z )
D. ( 100 H z )
12
729 The minimum potential difference between the base and emitter required
to switch a silicon transistor ( O N ) is
approximately
( mathbf{A} cdot 1 V )
B. ( 3 V )
c. ( 5 V )
D. ( 4.2 V )
12
730 Which logic gates mentioned below have the output value ‘O’ when both the inputs are 1
( A cdot O R, N A N D )
B. AND, NOR
c. AND, OR
D. NOR, NAND
12
731 What is the output of the combination? 12
732 When is a transistor said to be in active
state? Draw a circuit diagram of a p-np transistor and explain how it works as
a transistor amplifier. Write clearly, why in the case of a transistor
(i) the base is
thin and lightly doped and (ii) the emitter is heavily doped.
12
733 What would be the output of the circuit whose boolean expression ( boldsymbol{Y}=boldsymbol{A} overline{boldsymbol{B}}+ )
( A B ) when ( A=1, B=0 ? )
( A )
B.
c. Both (A) & (B)
D. None of these
12
734 The highest energy band which is filled at zero Kelvin is called
A. conduction band
B. valence band
c. insulation band
D. filled band
12
735 Write the two processes that take place
in the formation of a ( boldsymbol{p}-boldsymbol{n} ) junction.
Explain with the help of a diagram, the formation of the depletion region and barrier potential in a ( p-n ) junction.
12
736 Suppose a pure Si crystal has ( 5 times 10^{28} )
atoms ( m^{-3} . ) it is doped by 1 ppm
concentration of pentavalent As. Calculate the number of electrons and
holes. Given that ( n_{1}=1.5 times 10^{16} m^{-3} )
12
737 If ( alpha ) -current gain of a transistor is 0.98
What is the value of ( beta ) -current gain of
the transistor?
A . 0.49
B. 49
c. 4.9
D. 5
12
738 ( begin{array}{ccc}boldsymbol{A} & boldsymbol{B} & boldsymbol{Q} \ 0 & 0 & 0 \ 0 & 1 & 1 \ 1 & 0 & 1 \ 1 & 1 & 1end{array} )
The truth table is given above for which of the following gates is correct
A. NAND gate
B. OR gate
c. AND gate
D. NOT gate
12
739 The conductivity of a semi conductor can be increased by:
A. Heating the semi conductor
B. Doping the semi conductor
c. Both (a) and (b)
D. None
12
740 ILLUSTRATION 31.5 Write the truth table for a NAND gate
connected as given in figure.
12
741 On doping germanium with donor atoms of density ( 10^{17} mathrm{cm}^{-3} ) its conductivity in ( m h o / c m ) will be
( left[text { Given: } mu_{e}=3800 mathrm{cm}^{2} / V-s text { and } n_{i}=right. )
( left.2.5 times 10^{13} c m^{-3}right] )
A . 30.4
B. 60.8
c. 91.2
D. 121.6
12
742 Assertion
( mathbf{A} )
p-njunction with reverse bias can be used as a photodiode to measure light intensity.
Reason
In a reverse bias condition the current
is small but it is more sensitive to
changes in incident light intensity.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
743 In the given figure if ( V_{I N} ) increases then
( boldsymbol{I}_{z} ) will
A. change
B. decrease
( c . ) increase
D. does not change
12
744 Which of the following statement is not
true?
A. The resistance of an intrinsic semiconductor
decreases with increase in temperature
B. Doping pure ( S i ) with trivalent impurities gives ( p ) -type semiconductor
C. The majority carriers in n-type semiconductor are holes
D. a p-njunction can act as a semiconductor diode
12
745 The mobility of hole in a semiconductor depend on
A. Electric field
B. Potential difference
c. current
D. Mass
12
746 12. A working transistor with its three legs marked P. e
and R is tested using a multimeter, no conduction 15
found between P and O. By connecting the common
(negative) terminal of the multimeter to R and the other
(positive) terminal to Por Q, some resistance is seen on
the multimeter. Which of the following is true for the
transistor?
(a) It is a pnp transistor with R as emitter.
(b) It is an npn transistor with R as collector.
(c) It is an npn transistor with R as base.
(d) It is pnp transistor with R as collector.
(AIEEE 2008)
12
747 The photovoltaic effect is the creation of
a material upon exposure to light and is a physical and chemical phenomenon.
A. voltage or electric current
B. voltage
c. current
D. none of the above
12
748 The output characteristic of an ( n-p-n ) transistor represent:
( left[I_{C}=text { Collector current, } V_{C E}= ) potential right. difference between collector and
emitter, ( boldsymbol{I}_{B}= ) Base current, ( boldsymbol{V}_{boldsymbol{B} boldsymbol{B}}= )
voltage given to base; ( V_{B E}= ) the potential difference between base and emitter ( ] )
A. changes in ( I_{C} ) as ( I_{B} ) and ( V_{B B} ) are changed
B. changes in ( I_{C} ) with changes in ( V_{C E}left(I_{B}=text { constant }right) )
c. changes in ( I_{B} ) with changes in ( V_{C E} )
D. changes in ( I_{C} ) as ( V_{B E} ) is changed
12
749 27. In a common base amplifier circuit, calculate the change
in base current if that in the emitter current is 2 mA and
a= 0.98.
(a) 0.04 mA
(b) 1.96 mA
(c) 0.98 mA
(d) 2 mA
20
ENDN transistore thanallantan m
antan..
olau
12
750 A common emitter amplifier is designed with ( n ) -p-n transistor ( (alpha= )
0.99). The input impedance is ( 1 k Omega ) and
load is ( 10 k Omega . ) The voltage will be :
A . 9900
B. 99
c. 9.9
D. 990
12
751 Which of the following law(s) is/are included in Boolean algebra?
A. Commutative Law
B. Associative Law
c. Distributive Law
D. All of the above
12
752 The truth table given in figure
represents:
begin{tabular}{|c|c|c|}
hline ( mathrm{A} ) & ( mathrm{B} ) & ( mathrm{Y} ) \
hline 0 & 0 & 0 \
hline 0 & 1 & 1 \
hline 1 & 0 & 1 \
hline 1 & 1 & 1 \
hline
end{tabular}
A. AND-Gatt
B. NOR – Gate
c. NAND – Gate
DR – Gat
12
753 The output of the given circuit in the
figure.
A. would be zero at all times
B. would be like a half-wave rectifier with positive cycles in output
C. would be like a half -wave rectifier with negative cycles in output
D. would be like that of a full wave rectifier
12
754 The truth tables of logic gates ( A, B, C, D )
are given here. Identify them correctly.
begin{tabular}{|c|c|c|}
hline multicolumn{3}{|c|} { Input } & multicolumn{1}{c|} { Output } \
hline ( mathrm{A} ) & ( mathrm{B} ) & ( mathrm{Y} ) \
hline 0 & 0 & 0 \
0 & 1 & 1 \
1 & 0 & 1 \
1 & 1 & 1 \
hline
end{tabular} begin{tabular}{|l|c|c|}
hline multicolumn{2}{|c|} { Input } & Output \
hline ( mathrm{A} ) & ( mathrm{B} ) & ( mathrm{Y} ) \
hline 0 & 0 & 0 \
0 & 1 & 0 \
1 & 0 & 0 \
1 & 1 & 1 \
hline
end{tabular}
begin{tabular}{|l|l|l|}
hline multicolumn{2}{|c|} { Input } & multicolumn{1}{|c|} { Output } \
hline ( mathrm{A} ) & ( mathrm{B} ) & ( mathrm{Y} ) \
hline 0 & 0 & 1 \
0 & 1 & 0 \
1 & 0 & 0 \
1 & 1 & 0 \
hline
end{tabular} begin{tabular}{|l|c|c|}
hline multicolumn{2}{|c|} { Input } & multicolumn{1}{|c|} { Output } \
hline ( mathrm{A} ) & ( mathrm{B} ) & ( mathrm{Y} ) \
hline 0 & 0 & 1 \
0 & 1 & 1 \
1 & 0 & 1 \
1 & 1 & 0 \
hline
end{tabular}
A . A: OR
B: AND, C: NOR,
D: NAND
B. A: OR,
( B: ) NOR, ( C: A N D )
D: NAND
C. ( A: A N D )
B: OR, C: NAND,
D: NOR
D. A: OR
B: NOR, C: NAND,
D: AND
12
755 As the temperature of a transistor increases, the collector current will
A. increase
B. decrease
c. remain constant
D. depends on the situation
12
756 The equivalent circuit is :
A. NAND gates
B. OR gates
c. AND gates
D. NOR gates
12
757 The load voltage is approximately constant when a zener diode is
A. Forward-biased
B. Reverse-biased
c. operating in the breakdown region
D. Unbiased
12
758 One way in which the operation of an ( n ) –
( p-n ) transistor differ from that of a ( p-n-p )
transistor is that
A. the emitter junction is reverse biased in ( n-p-n )
B. the emitter junction injects minority carriers into the base region of the ( mathrm{p}-mathrm{n}-mathrm{p} )
C. the emitter injects holes into the base of the pnp and electrons into the base region of ( n-p-n )
D. the emitter injects holes into the base of ( n-p-n )
12
759 If ( boldsymbol{A}=boldsymbol{B}=mathbf{1}, ) then in terms of Boolean
algebra the value of ( boldsymbol{A} . boldsymbol{B}+boldsymbol{A} ) is not
equal to
( mathbf{A} cdot B cdot A+B )
в. ( B+A )
( c . B )
D. ( bar{A} . B )
12
760 35. A transistor is used in a common-emitter mode in an
amplifier circuit. When a voltage of 20 mV is added to
the base-emitter voltage, the base current changes by
20 uA and the collector current changes by 2 mA. The
load resistor is 5 k 2. What is the volume of B?
(a) 10
(b) 100
(c) 1000
(d) 106
12
761 In an insulator, the energy gap
between conduction band and valence
band is about
A. 0 eV
B. 6 eV
( c cdot 1 e V )
D. 0.6 eV
12
762 In the given circuit the current through
Zener Diode is close to :
( mathbf{A} cdot 6.0 m )
в. ( 4.0 mathrm{m} ) А
( c .6 .7 m A )
D. ( 0.0 mathrm{mA} )
12
763 The following truth table corresponds to the logic gate
( begin{array}{ccc}mathbf{A} & mathbf{B} & mathbf{X} \ 0 & 0 & 0 \ 0 & 1 & 1 \ 1 & 0 & 1 \ 1 & 1 & 1end{array} )
A. NAND
B. OR
C . AND
D. xor
12
764 To obtain n-type extrinsic semiconductor, the impurity element to be added to germanium should be of valency
A .2
B. 5
( c cdot 4 )
( D )
12
765 What is rectifier? Explain with neat circuit diagram the action of semiconductor diode as a full wave
rectifier.
12
766 (i) Write the truth tables of the logic
gates market ( boldsymbol{P} ) and ( boldsymbol{Q} ) in the given
circuit.
(ii) Write the truth table for the circuit
12
767 In the given circuit, value of ( Y ) is:
A . toggles between 0 and 1
B.
c. will not execute
( D )
12
768 34. The current gain a of a transistor in common-base mode
is 0.995. Its gain Bin the common-emitter mode is nearly
(a) 9.5
(b) 1.005
(c) 200
(d) 100
12
769 If ( V_{B}=5 V ), then the maximum value of ( R )
so that the voltage ( V ) is above the knee
point voltage, should be
( A cdot 0.7 times Omega )
в. 4.3 К.
( c cdot 5 K Omega )
D. 5.7 к.
12
770 Draw diagram for a P-N junction to obtain reverse bias characteristic
curves. Explain the phenomenon of reverse breakdown for a P-N junction in reserve bias state by following
processes-
(i) Avalanche breakdown
(ii) Zener breakdown
12
771 Doping of silicon with indium leads to
which type of semiconductors?
12
772 To get an output of 1. from the circuit
shown in figure the input must be
( mathbf{A} cdot a=0, b=0, c=1 )
B ( . a=1, b=0, c=0 )
( mathbf{c} cdot a=1, b=0, c=1 )
D . ( a=0, b=1, c=0 )
12
773 In a transistor output characteristics
commonly used in common emitter con
ig ration, the base current ( boldsymbol{I}_{B}, ) the
collector current ( I_{C} ) and the collector-
emitter voltage ( V_{C E} ) have values of the
following orders of magnitude in the
active region
( mathbf{A} cdot I_{B} ) and ( I_{C} ) both are in ( mu A ) and ( V_{C E} ) in Volts
B. ( I_{B} ) is in ( mu A ), and ( I_{C} ) is in ( m A ) and ( V_{C E} ) in Volts
( mathbf{C} cdot I_{B} ) is in ( m A, ) and ( I_{C} ) is in ( mu A ) and ( V_{C E} ) in ( m V )
D. ( I_{B} ) is in ( m A ), and ( I_{C} ) is in ( m A ) and ( V_{C E} ) in ( m V )
12
774 Silicon is not suitable for fabrication of
light emitting diodes because it is:
A. an indirect band gap semiconductor
B. a direct band gap semiconductor
c. a wide band gap semiconductor
D. none of the above
12
775 If ( A=1 ) and ( B=0, ) then in terms of
Boolean algebra the value of ( A . A+B ) is
A . ( A )
B. ( B^{2} )
( c . B )
D . ( A cdot B )
12
776 To a germanium sample, traces of gallium are added as an impurity. The resultant sample would behave like
A. a conductor
B. a p-type semiconductor
c. an n-type semiconductor
D. a insulator
12
777 In positive logic, the logic state 1
corresponds to
A. positive voltage
B. zero voltage
c. lower voltage level
D. higher voltage leve
12
778 A common emitter transistor amplifier
has a current gain of ( 50 . ) If the load resistance is ( 4 k Omega, ) and input
resistance is ( 500 Omega, ) the voltage gain of amplifier is :
A. 100
в. 200
c. 300
D. 400
12
779 Which of the following applications is not based on use of ICs?
A. Microprocessor chip.
B. Laptops and personal computers.
c. Mobile phones.
D. Transformers
12
780 If an LED has to emit 662 nm wavelength
of light them what should be the band gap energy of its semiconductor? ( boldsymbol{h}= )
( 6.62 times 10^{-34} mathrm{Js} )
12
781 Photo-diode is operated in reverse bias
because
A. When the diode is reversed biased, no ordinary current flows and the detection of the photo-current is much easier
B. When the diode is reversed biased, ordinary current flows and the detection of the photo-current is much easier
C. In reverse biased it will conduct a lot of current and can’t detect the small amount of excess current produced by the photoelectric effect
D. All of the above
12
782 As the temperature of a transistor
increases,
A. The base-emitter voltage required for a given collector current will decrease
B. The base-emitter voltage required for a given collector current will increase
C. The base-emitter voltage required for a given collector current will remain constant
D. The base-emitter voltage required for a given collector current will be indeterminate
12
783 The output of the combination of the
gates shown in the figure is
( mathbf{A} cdot A+A cdot B )
B . ( (A+B) A+bar{B} )
c. ( (A . B)+(bar{A} . bar{B}) )
D. ( (A+B)(overline{A . B}) )
12
784 36. In question 35, the input resistance is
(a) 1 ΚΩ
(b) 2 ΚΩ
(c) 3 kΩ
(d) 4 ΚΩ
12
785 Why is a photo-diode invariably reverse
biased, when it is used as a photo-
detector?
A. The power consumption is much reduced compared to reverse biased condition
B. Electron hole pairs can be produced by the incident photons only if the photo diode is reverse biased
C. Light variations can be converted into current variations only if the photo diode is reverse biased
D. When photons are incident on the diode, the fractional change in the reverse current is much greater than the fractional change in the forward current
E. The photo diode will be spoilt if it is operated under forward biased condition
12
786 3. A photodetector is made from a semiconductor
In 0.53 Ga 0.47As with E, = 0.73 eV. What is the maximum
wavelength, which it can detect
(a) 1000 nm
(b) 1703 nm
(c) 500 nm
(d) 173 nm
12
787 Two ideal junction diodes ( D_{1}, D_{2} ) are
connected as shown in the figure. A ( 3 V )
battery is connected between ( A ) and ( B ) The current supplied by the battery, if its positive terminal is connected to B
is
A ( .0 .15 ~ A )
в. 0.3 А
( c .3 A )
D. 1.4
12
788 Among the following one can act as the building blocks for the other gates is
A. NAND and NOR
B. NAND and AND
c. xor and or
D. NOT and OR
12
789 The band gaps of an insulator, conductor and semi conductor are
respectively ( boldsymbol{E}_{boldsymbol{g} 1}, boldsymbol{E}_{boldsymbol{g} mathbf{2}} ) and ( boldsymbol{E}_{boldsymbol{g} mathbf{3}} . ) The
relationship between them is given as
A ( . E_{g 1}>E_{g 2}E_{g 2}>E_{g 3} )
C ( . E_{g 1}E_{g 3} )
D. ( E_{g 1}<E_{g 2}<E_{g 3} )
12
790 How many electrons are there is the
outermost shell of silicon atom?
12
791 To which logic gate does the truth table given below correspond?
( begin{array}{ccc}mathbf{A} & mathbf{B} & mathbf{Y} \ 0 & 0 & 1 \ 1 & 0 & 1 \ 0 & 1 & 1 \ 1 & 1 & 0end{array} )
A. OR gate
B. AND gate
c. NAND gate
D. NOR gate
12
792 The electrical conductivity of a semiconductor increases when
electromagnetic radiation of wavelength shorter than 2480 nm is incident on it. The forbidden band
energy for the semiconductor in ( e V ) is
A . 0.5
B. 0.9
( c .0 .7 )
D. 1.
12
793 A strip of copper and another of germanium are cooled from room
temperature to ( 80 K ). The resistance of
A. each of these decreases.
B. copper strip decreases and that of germanium decreases
C. copper strip decreases and that of germanium increases
D. each of these increases.
12
794 Analyse the given circuit diagram of a half wave rectifier and answer the
following questions.
a.Identify the components labelled as
( M ) and ( N )
What are the changes to be made in
the following components for the
converting this to a full wave rectifier
I. Transformer
ii. No.of Dioder
iii. Draw the output form of a fill
rectifier.
12
795 When the source voltage increases in a zener regulator, which of these currents
remains approximately constant?
A. Series current
B. zener current
c. Load current
D. Total current
12
796 Symbolic representation of photodiode
is-
( A )
B.
( c )
( D )
12
797 Silicon nitride has band gap energy of
( e v )
12
798 Distinguish between n type and p type
semi conductors.
12
799 State whether given statement is True or False

The depletion layer in the p-njunction region is caused by diffusion of carriers.
A. True
B. False

12
800 State the properties and uses of a
Junction transistor
12
801 Zener diode is used for
A. amplification
B. rectification
C. stabilisation
D. all of the above
12
802 Assume that the number of hole-
electron pair in an intrinsic
semiconductor is proportional to
( e^{Delta E / 2 k T} . ) Here ( Delta E= ) energy gap and
( boldsymbol{k}=mathbf{8 . 6 2} times mathbf{1 0}^{mathbf{5}} boldsymbol{e V} / boldsymbol{K} . ) The energy gap
for silicon is ( 1.1 e V . ) The ratio of electron
hole pairs at ( 300 K ) and ( 400 K ) is
( mathbf{A} cdot e^{5.104 times 10^{-8}} )
B ( cdot e^{-5} )
( c cdot c )
D. ( e^{2} )
12
803 A hole is:
A. a positively charged electron
B. an electron in valence band
c. an unfilled covalent bond
D. an excess electron in covalent bond
12
804 When a forward bias is applied to ( mathrm{p}-mathrm{n} ) junction it:
A. Raises the potential barrier.
B. Reduces the majority carrier current to zero.
c. Lowers the potential barrier.
D. None of the above
12
805 50. How many NAND gate are used to form AND gate?
(a) 1
(b) 2
(c) 3
(d) 4
12
806 42. In question 38, the change in output across load is
(a) 5 V
(b) 10 V
(c) 15 V
(d) 16 V
12
807 Explain the use of N-P-N Transistor as an amplifier in common emitter mode under the following heads.
(i) Labelled circuit diagram. (ii) Working.
12
808 If the forward voltage in a semiconductor diode is changed from ( 0.5 V ) to ( 0.7 V, ) then the forward current
changes by ( 1.0 m A . ) The forward resistance of diode junction will be
( mathbf{A} cdot 100 Omega )
в. ( 120 Omega )
c. ( 200 Omega )
D. 240Omega
12
809 When the band gap for a semiconductor
is low
A. conductivity of that material is low
B. conductivity of that material is highh
c. the resistance of that material is highh
D. none of the above
12
810 In which of the configurations of a transistor, the power gain is highest?
A. Common base
B. Common emitter
c. common collector
D. Same in all the three
12
811 If the resistivity of an alloy is ( rho^{prime} ) and that
of constituent metal is ( rho ) then :
A ( cdot rho^{prime}>rho )
B . ( rho^{prime}<rho )
C ( cdot rho^{prime}=rho )
D. there is no simple reaction between ( rho^{prime} & rho )
12
812 In an n-p-n transistor circuit, the
collector current is ( 9 mathrm{mA} ). If ( 90 % ) of the
electrons emitted reach the collector.
Then the emitter current is
( A cdot 8.1 mathrm{mA} )
B. 8 mA
( c cdot 9 m A )
D. ( 10 mathrm{mA} )
12
813 4. A pure semiconductor has equal electron and hole
concentration of 100m-. Doping by indium increases nn
to 4.5 x 1022 m². What is n in the doped semiconductor?
(a) 100 m-
(b) 1022 m-
(d) 4.5 x 1022 m-
1032
(c)
4.5×1022 m3
12
814 Avalanche breakdown is primarily dependent on the phenomenon of :
A . Collision
B. Ionisation
c. Doping
D. Recombination
12
815 The value of ( overline{1}+overline{1} ) is
( A cdot 2 )
B. 0
( c .1 )
D. 10
12
816 E. Negative temperature
A. Hole ( quad ) coefficient of resistance
B. Copper
F. Energy vacancy
G. Positive temperature coefficient
C. Doping ( quad ) of resistance
H. Addition of impurity to increase
D. ( quad ) the conductivity Germanium
Charges are holes and electrons
Match the above lists:
( A cdot A-H, I B-E C-F D-G )
B. A-E B-F,I C-G D-H
C ( . ) A-F B-G C-H D-E,
D. A-G,I B-H C-E D-F
12
817 In a semiconductor
A. There are no free electrons at any temperature
B. The number of free electrons is more than in a
conductor
C. There is no free electrons at OK
D. None of these
12
818 What are semiconductors? Give
examples.
12
819 A ( p ) -type semiconductor has acceptor levels 57 me ( V ) above the valance band.
The maximum wavelength of light required to create a hole is (Planck’s
constant ( left.h=6.6 times 10^{-34} J-sright) )
A ( .57 AA )
В. ( 57 times 10^{-3} dot{A} )
c. 217100 月
D . ( 11.61 times 10^{-33} dot{A} )
12
820 For a P-Njunction diode.
A. Forward current in ( mathrm{mA} ) and reverse current is in ( mu A )
B. Forward current is in ( mu A ) are reverse current is in ( mathrm{mA} )
C. Both forward and reverse currents are in ( mu A )
D. Both forward and reverse currents are in ( mathrm{mA} )
E. No current flows in any direction
12
821 What is the order of magnitude of the resistance of a dry human body?
A . ( 10 Omega )
B . ( 10^{4} Omega )
c. 10 МOmega
D. ( 10 mu Omega )
12
822 The typical operating current for a lightemitting diode is approximately:
A .1 to ( 5 m A )
B. 5 to ( 20 m A )
c. 20 to ( 500 m A )
D. 500 to ( 2000 m A )
12
823 The colour of light emitted by an LED depends on
A. Its reverse bias
B. The amount of forward current
c. Its forward bias
D. Type of semiconductor material
12
824 Which one is the weakest type of bonding in solids?
A. Ionic
B. Covalent
c. Metallic
D. vander wall’s
12
825 Thermistor material is pressed
A. under zero pressure
B. under low pressure
c. under high pressure
D. under low volume
12
826 If the bandgap between valence band
and conduction band in a material is
0 ( e V ), then the material is
A. Semiconductor
B. Good conductor
c. superconductor
D. Insulator
12
827 (a) Describe briefly, with the help of a diagram, the role of the two important processes involved in the formation of a
( p-n ) junction
(b) Name the device which is used as a
voltage regulator. Draw the necessary circuit diagram and explain its working.
12
828 Doping of intrinsic semiconductor is
done
A. To neutralize charge carriers
B. To increase the concentration of majority charge carriers
C. To make it neutral before disposal
D. To carry out further purification
12
829 Why does the thickness of depletion layer of pn-junction increases in reverse biasing ?Draw the circuit diagram of reverse biasing. 12
830 The immpurity atoms with which pure silicon should be doped to make a ( mathrm{p} ) type semiconductor are those
This question has multiple correct options
A. Boron
B. Aluminium
c. Phosphorus
D. Antimony
12
831 What does LED stand for?
A. Light emitting display
B. Light energy display
C. Light emitting diode
D. Light emitting detector
12
832 46. Which gate is represented by this figure?
(a) NAND gate
(b) AND gate
(c) NOT gate
(d) OR gate
12
833 Light of wavelength ( 6000 mathrm{nm} ) falls on a
p-njunction photodiode. This photodiode is fabricated from a semiconductor with a band gap of 2.8
eV. Then, which of the following statement is true?
A. This wavelength is not detected by the photodode
B. This wavelength is detected by the photodiode
c. Light is reflected back completely
D. None of the above
12
834 Which of the following statement(s) is/are correct
This question has multiple correct options
A. If the band gap becomes much more higher for a semiconductor then electrons from lower energy state can’t move to higher energy state
B. Lesser the band gap lesser is the conduction
C. Lesser the band gap higher is the conduction
D. none of the above
12
835 62. With reference to the figure which of the following is
possible?
(a) A = 0, B = 0, X = 1
(c) A = 0, B = 0, X = 0
(b) A = 0, B = 1,X=0
(d) A = 1, B = 1,X=0
12
836 The order of size of an IC is:
( mathbf{A} cdot 10^{-3}-10^{-1} m )
B ( cdot 10^{1}-10^{3} m )
C ( cdot 10^{-1}-10^{1} m )
D. ( 10^{-9}-10^{-6} m )
12
837 How many minimum NAND GATEs are
required for obtaining an output of ( A . B+C . D ? )
12
838 The part of a trasistor which is heavily doped to produce large number of majority carriers is :
A . emitter
B. base
c. collector
D. can be any of the above three
12
839 Assume that each diode as shown in
the figure has a forward bias resistance
of ( 50 Omega ) and an infinite reverse bias
resistance. The current through the
resistance ( 150 Omega ) is:
A ( .0 .66 A )
B. ( 0.05 A )
c. zero
D. ( 0.04 A )
12
840 The diffusion current in a p-njunction
is greater than the drift current when the junction is
A. forward biased.
B. reverse biased
c. unbiased.
D. both forward and reverse biased
12
841 In p-type semiconductor major current carriers are:
A. negative ions
B. holes
c. electrons
D. all of these
12
842 Which one of the following diagrams correctly represents the energy levels in the p-type semiconductor?
( A )
в.
Band
gap
( c )
band
D.
Conduction band
12
843 Wavelength of a laser beam can be used as a standard of:
A. time
B. temperature
c. angle
D. length
12
844 33. The current gain for a transistor used in common-emitte
configuration is 98. If the load resistance is 1 MS and the
internal resistance is 60 S2, what is the voltage gain
(a) 90
(b) 95
(c) 100
(d) None of the above
12
845 Explain the working of a diode as half wave rectifier. 12
846 The bond, that exists in a
semiconductor is
A. covalent bond
B. ionic bond
c. metalic bond
D. hydrogen bond
12
847 For filtering low frequency noise out of a signal the circuit can be built by just putting resistor and capacitor in
A. Series
B. Parallel
c. Perpendicular
D. Bipolar
12
848 Which of the following is an example of a direct band gap
intrinsic semiconductor?
A. Silicon
B. Germanium
c. Gallium Arsenide
D. none of these
12
849 The width of the depleted region of a p-n junction is of the order of a few tenth of
( mathbf{a} )
A. millimeter
B. micrometer
c. metre
D. nanometre
12
850 For silicon, the energy gap at ( 300 K ) is
( mathbf{A} cdot 1.1 W )
в. ( 1.1 J )
c. ( 1.1 e V )
D. None of these
12
851 In the diagram shown below, the input
is across the terminals ( A ) and ( C ) and the
output is across ( B ) and ( D ) Then the
output is
A. Zero
B. Same as input
c. Full wave rectified
D. Half wave rectified
12
852 toppr 5
Q Type your question
( B )
( c )
( D )
12
853 Assertion
Semiconductors are solids with
conductivities in the intermediate
range from ( 10^{-6}-10^{4} ) ohm ( ^{-1} m^{-1} )
Reason
Intermediate conductivity in
semiconductor is due to partially filled
valence band.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
854 A Zener diode when used as a voltage
regulator, is connected
(a) in forward bias.
(b) in reverse bias.
(c) in parallel to the load.
(d) in series to the load.
A. (a) and (b) are correct
B. (b) and (c) are correct
c. (a) only is correct
D. (d) only is correct
12
855 With the help of a diagram, show how you can use several NAND gates to
obtain an OR gate.
12
856 Which of the following statement(s) is/are correct:
A. The gap between the top of the valance band and the bottom of the conduction band is called energy band ( operatorname{gap} )
B. More band gap results in less electron transfer
c. A semiconductor is a material with a small but nonzero band gap that behaves as an insulator at absolute zero
D. All of the above
12
857 51. Sum of the two binary numbers (1000010), and (11011), is
(a) (111101)2
(b) (111111)2
(c) (101111)2
(d) (111001),
12
858 1. A 2 V battery is connected across the points A and B as
shown in the figure given
102
below. Assuming that the
resistance of each diode is
102
zero in forward bias and
infinity in reverse bias, the
current supplied by the
battery when its positive
AB
terminal is connected to A is
(a) 0.2 A
(b) 0.4 A
(c) Zero
(d) 0.1 A
12
859 Draw the typical input and output characteristic of an ( n-p-n )
transistor in ( C E ) configuration. Show
how these characteristics can be used
to determine (a) the input resistance
( left(r_{i}right), ) and
(b) current amplification
factor ( (boldsymbol{beta}) )
12
860 Alternating current is converted to direct current by
A . rectifier
B. dynamo
c. transformer
D. motor
12
861 Electric conduction in a semiconductor
takes place due to
A. electrons only
B. holes only
c. both electrons and holes
D. neither electrons nor holes
12
862 In graphs of the electronic band
structure of solids, the band gap
generally refers to the
between the top of the valence band and
the bottom of the conduction band in
insulators and semiconductors.
A. current difference
B. energy difference (in electron volts)
c. hole difference
D. none of the above
12
863 Plot a graph showing variation of current versus voltage for the material
Ga.
12
864 The voltage gain of the following amplifier is
A . 10
B. 100
c. 1000
D. 9.9
12
865 State whether given statement is True or False
The resistance of intrinsic
semiconductors increase with increase
in temperature
A. True
B. False
12
866 Draw a circuit diagram of a transistor amplifier in CE configuration
Define the terms:
(i) Input resistance and
(ii) Current
amplification factor. How are these determined using typical input and output characteristics?
12
867 A storage battery takes ( t_{0} ) time when
DC current ( I_{0} ) is used to charge it. Find
the time taken if a half wave rectifier is
used with ( A C ) mains and effective
current is ( boldsymbol{I}_{0} )
A ( cdot t_{0} pi )
в. ( frac{2 t_{0}}{pi} )
c. ( frac{pi t_{0}}{2} )
D. ( t )
12
868 If in a p-njunction diode, a square input signal of ( 10 V ) is applied as shownThen
the output signal across ( R_{L} ) will be
( A )
в.
( c )
D.
12
869 If ( V_{A} ) and ( V_{B} ) denote the potentials of ( A )
and ( mathrm{B} ), then the equivalent resistance
between ( A ) and ( B ) in the adjoint electric
circuit is
( A cdot 10 Omega ) if ( V_{A}>V_{B} )
B. ( 5 Omega ) if ( V_{A}V_{B} )
D. ( 20 Omega ) if ( V_{A}>V_{B} )
12
870 Energy band gap between valence band and conduction band for conductor is:
A. more than semiconductors
B. Zero
c. more than insulators
D. None of these
12
871 The output current versus time curve for a rectifies is shown in the figure. The
average value of output current in this case is
( A )
в. ( frac{I_{0}}{2} )
c. ( frac{2 I_{0}}{pi} )
( D cdot l_{0} )
12
872 half

malf
8. The circuit shown in following figure contains two diode
D, and D, each with a forward resistance of 50 ohms and
with infinite backward resistance. If the battery voltage is
6 V, the current through the 100
1502
ohms resistance (in amperes) is
(a) Zero
SO2
(b) 0.02
(c) 0.03
(d) 0.036
6 V
(1) Acording to the given polarity diode is forward
ng
1002
ite
ca
12
873 NAND gate in the following is
( A )
в.
( c )
D.
12
874 (i) Distinguish between a conductor
and a semi conductor on the basis of
energy band diagram
(ii) The following figure shows the input waveforms ( (A, B) ) and the output waveform (Y) of a gate. Identify the gate, write its truth table and draw its logic symbol.
12
875 In solar cells, a silicon solar cell ( (mu= )
3.5) is coated with a thin film of silicon
monoxide ( boldsymbol{S} boldsymbol{i} boldsymbol{O}(boldsymbol{mu}=mathbf{1 . 4 5}) ) to minimise
reflective losses from the surface.
Determine the minimum thickness of
SiO that produces the least reflection
at a wavelength of ( 550 n m, ) near the centre of the visible spectrum.
12
876 For a common emitter amplifier, the current gain is ( 70 . ) If the emitter current
is ( 8.8 mathrm{mA} ), then the collector current is:
( mathbf{A} cdot 0.124 m A )
в. ( 4.34 m A )
( c .8 .68 m A )
D. ( 1.72 m A )
12
877 The impurity atoms with which pure silicon would be doped to make a p-type semiconductor are those of
This question has multiple correct options
A. Phosphorus
B. Boron
C. Antimony
D. Aluminium
12
878 Which among the following is an example of a semiconductor?
A. cuprous oxide
B. iron
c. copper
D. aluminium
12
879 In n-type semiconductors, the electron concentration is equal to:
A. density of donor atoms
B. density of acceptor atoms
C. density of both type of atoms
D. neither density of acceptor atoms nor density of donor atoms
12
880 Identify the logic operation of the following logic circuit:
A. NAND
B. AND
c. Non
D. on
12
881 What will be the input of ( A ) and ( B ) for Boolean expression
[
(overline{A+B})(overline{A cdot B})=1
]
A .0,0
в. 0,1
c. 1,0
D. ( 1, )
12
882 In ( V ) -1 characteristic of a p-n junction, reverse biasing results in
A. leakage current
B. the current barrier across junction increases
c. no flow of current
D. large current
12
883 Assertion
Diode lasers are used as optical sources in optical communication.
Reason

Diode lasers consume less energy.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect

12
884 Which among the following having highest band gap?
A. Diamond
B. Silicon
c. Germanium
D. Gallium nitride
12
885 The thickness of depletion layer is approximately
A . ( 1 mu m )
B. ( 1 mathrm{mm} )
( c cdot 1 c m )
D. ( 1 m )
12
886 In the circuit diagram, the current
through the Zener diode is :
( mathbf{A} cdot 10 m A )
B. ( 3.33 m A )
( mathbf{c} cdot 6.67 m A )
( mathbf{D} cdot 0 m A )
12
887 In common emitter amplifier, the current gain is ( 62 . ) The collector resistance and input resistance are ( 5 k Omega ) an ( 500 Omega )
respectively. If the input voltage is ( 0.01 V, ) the output voltage is
A. ( 0.62 V )
V
B. ( 6.2 V )
( c .62 V )
D. ( 620 V )
12
888 The diagram of a logic circuit is given below, the output of the circuit is
represented by
( A cdot W+(X+Y) )
B. ( w+(x . y) )
( c . w .(x+y) )
D. w. (x.y)
12
889 ILLUSTRATION 31.3
In a p-n junction diode, the current I can
(ev
be expressed as, 1 = 1. ex
where 1is called the
(KBT
reverse saturation current, Vis the voltage across the diode and
is positive for forward bias and negative for reverse bias, and
I is the current through the diode, kr is the Boltzmann constant
(8.6 x 10eV/K) and T is the absolute temperature. If for a
diode, 10 = 5 x 10-2 A and T = 300 K, then
(a) what will be the forward current at a forward voltage of
0.6 V?
(b) what will be the increase in the current if the voltage across
the diode is increased to 0.7 V?
(c) what is the dynamic resistance?
(d) what will be the current if reverse bias voltage changes
from 1 V to 2 V?
12
890 6. A p-n junction diode when forward-biased has a drop of
0.5 V. We want to see 1.5 V battery to forward-bias the
diode. What resistance must be connected in series with
the diode so that the maximum current does not exceed
1 mA?
(a) 10-32
(b) 100 22
(c) 10 2
(d) 10° 22 in
12
891 The conductivity of intrinsic semiconductor decreases with increase
in temperature
A. True
B. False
12
892 In a common-base mode of a transistor,
the collector current is 5.488 mA for an
emitter current of 5.60 mA. The value of
the base current amplification factor ( (boldsymbol{beta} )
will be
A .49
B. 50
( c cdot 51 )
D. 48
12
893 Which of following gates produces
output of ( 1 ? )
( A )
B
( c )
( D )
12
894 A Zener diode, having breakdown
voltage equal to ( 15 V ) is used in a
voltage regulator circuit shown in
figure. The current through the diode is
( A cdot 10 m A )
B. ( 15 m A )
( c cdot 20 m A )
( mathbf{D} cdot 5 m A )
12
895 Across the depletion region, there is a
barrier potential which
A. prevents the movement of electron from the n region into the p region
B. prevents the movement of electron from the p region into the n region
C. prevents the movement of holes from the n region into the p region
D. prevents the movement of holes from the p region into the n region
12
896 In N-type semiconductors, holes are:
A. majority carriers
B. minority carriers
( c . ) absent
D. none of these
12
897 Which of the following has least band
gap energy at ( 273 K )
A . Insb
B. InAs
( c cdot ln P )
D. Gasb
12
898 Give two example of intrinsic semiconductor?
A . aluminum
B. Silicon, germanium
c. copper
D. nitrogen
12
899 toppr
Q туре your question
currents is ( frac{7}{4}, ) then what is the ratio of
their drift velocities?
(1)
(2)
(3)
12
900 In a ( p ) -type semiconductor germanium
is doped with:
A. Gallium
B. Aluminium
c. Boron
D. All of the above.
12
901 The depletion region in a semiconductor diode is formed at the
Junction.
A. True
B. False
12
902 When pure semimconductor is doped
then its electrical conductivity
A. increases
B. decreases
c. remains constant
D. initially increases and then decreases
12
903 The following represent standrard
symbols for transistors.
( (i) )
(i)
A. both represent PNP transistors
B. both represent NPN transistors
C. (i) represents PNP transistor while (ii) represent the NPN transistor
D. (i) represents NPN transistor while (ii) represent the PNP transistor
12
904 What is meant by forward bias and reverse bias of a diode? Indicate in a
figure.
12
905 Let ( n_{p} ) and ( n_{e} ) be the number of holes
and conduction electrons in an
extrinsic semiconductor. Then
A ( cdot n_{p}>n_{e} )
в. ( n_{p}=n_{e} )
c. ( n_{p}<n_{e} )
D ( cdot n_{p} neq n_{e} )
12
906 28. In case of NPN-transistors, the collector current is always
less than the emitter current because
(a) collector side is reverse biased and emitter side is
forward biased
(b) after electrons are lost in the base and only remaining
ones reach the collector
(c) collector side is forward biased and emitter side is
reverse biased
(d) collector being reverse biased attracts less electrons
12
907 Choose the correct statement:
A. Integrated circuits are less efficient in performance at all voltages.
B. Integrated circuits are more efficient in performance at low voltages.
C. Integrated circuits are less efficient in performance at high voltages.
D. Performance of an integrated circuit is independent of the magnitude of applied voltage.
12
908 Can we take one slab of p-type semiconductor and physicallyjoin it to another n-type semiconductor to get ( p-n )
junction?
12
909 If the rms value of sinusoidal input to a full wave rectifier is ( frac{v_{o}}{sqrt{2}}, ) then the rms value of the rectifier’s output is?
A ( cdot frac{v_{o}}{sqrt{2}} )
B. ( frac{v_{o}^{2}}{sqrt{2}} )
c. ( frac{v_{o}^{2}}{2} )
D. ( sqrt{2} V_{o}^{2} )
E ( .2 V_{o}^{2} )
12
910 A system of logic gates is shown in the figure. From the study of truth table it can be found that to produce a high output (1) at ( R, ) we must have
в. ( X=1, Y=1 )
c. ( X=1, Y=0 )
D. ( X=0, Y=0 )
0
12
911 Given : A and B are input terminals.
( operatorname{Logic} 1=>5 V )
( operatorname{Logic} mathbf{0}=<mathbf{1} boldsymbol{V} )
Which logic gate operation, the following circuit does?
( A ). AND Gate
B. OR Gate
c. XOR Gate
D. NOR Gate
12
912 The diagram of a logic gate circuit is
given below. The output ( Y ) of the circuit
is represented by
A ( . A cdot(B+C) )
B. ( A cdot(B cdot C) )
c. ( A+(B cdot C) )
( mathbf{D} cdot A+(B+C) )
12
913 The main cause of Zener breakdown is
A. the base semiconductor being germanium.
B. production of electron-hole pairs due to thermal excitation.
C . low doping.
D. high doping.
12
914 A Zener diode, having breakdown
voltage equal to ( 15 V ), is used in a
voltage regulator circuit shown in
figure. The current through the diode is
A . ( 10 mathrm{mA} )
в. ( 15 mathrm{mA} )
( c .20 m A )
D. ( 5 m A )
12
915 Zener diode works on
A. zero bias
B. reverse bias
C. forward bias
D. infinite bias
12
916 Symbols in (I) and (II) represent
standard transistors. Then
A. both represents p-n-p transistors
B. both represents n-p-n transistors
c. (I) represents n-p-n and (II) represents ( p ) -n-p.
D. (I) represents p-n-p and (II) represents n-p-n-
12
917 Which of the following are correct for
insulators?
A. The valence band is partially filled with electrons.
B. The conduction band is partially filled with electrons.
C. The conduction band is partially filled with electrons and valence band is empty.
D. The conduction band is empty and the valence band is filled with electrons.
12
918 From the circuit shown below, the
maximum and minimum value of zener
diode current are :
( mathbf{A} cdot 6 m A, 5 m A )
B. ( 14 mathrm{mA}, 5 mathrm{mA} )
( mathbf{c} .9 m A, 1 m A )
D. ( 3 m A, 2 m A )
12
919 In a n-type semiconductor, which of the following statement is true?
A. Electrons are majority carriers and trivalent atoms are dopants
B. Electron are minority carriers and pentavalent atoms are dopants.
C. Holes are minority carriers and pentavalent atoms are dopants.
D. Holes are majority carriers and trivalent atoms are dopants
12
920 Draw the diagram of a Helium-Neon laser tube and label the parts. 12
921 64. The process of negative feedback in electronics can
involve returning a fraction of the output of an operational
amplifier to the input. This may affect the gain and the
bandwidth (the range of frequency over which the gain
is constant). Which one of the following combinations of
effects is correct?
Effect on gain Effect on bandwidth
(a) Increased
Decreased
(b) Decreased
Decreased
(c) Increased
Unchanged
(d) Decreased
Increased
12
922 Which of the following semi-conducting devices is used as voltage regulator?
A. Zener diode
B. LASER diode
c. Photo diode
D. Solar cell
12
923 Power gain for ( N-P-N ) transistor is
( 10^{6}, ) input resistance ( 100 Omega ) and output
resistance ( 1000 Omega ). find out current
gain.
A. 100
в. 150
( c cdot 200 )
D. 50
12
924 In a semiconductor, the energy gap
between valence band and conduction
band is of the order of
A . Mev
B. kev
( c cdot e v )
D. Gev
12
925 21. In a common emitter amplifier circuit using an n-D-n
transistor, the phase difference between the input and the
output voltages will be
(a) 135°
(b) 180°
(d) 90° (JEE Main 2017)
(C) 45°
12
926 Choose the correct statements:
This question has multiple correct options
A. It is easier to fabricate 10000 AND gates using circuit components than on an integrated chip.
B. It is easier to fabricate 10000 AND gates on an integrated chip than fabricating them using circuit components.
C. It is easier to fabricate a single AND gate using circuit components as compared to on an IC.
D. It is easier to fabricate a single AND gate on an IC as compared to using circuit components.
12
927 Write down the truth table for the given
logic circuit with Boolean expression
12
928 A p-n photodiode is made of a material
with a band gap of ( 2.0 mathrm{eV} ). The minimum frequency of radiation that can be absorbed by the material is nearly:
12
929 In a transistor, the base is
A. a conductor of low resistance
B. a conductor of high resistance
C. an insulator
D. an extrinsic semiconductor
12
930 A pure semiconductor at absolute zero
has
A. Absence of electrons in the conduction band.
B. All the electrons occupying the valence band.
C . Large ( E_{g} ) value.
D. All of the above.
12
931 The current gain in common base
amplifier is
A . high
B. very low
c. about 1
D. very high
12
932 Construct a AND gate using only NOR gates only 12
933 The battery connections required to forward bias a pnjunction are
A. tve terminal to p and -ve terminal to ( n )
B. -ve terminal to p and +ve terminal to n
c. – -ve terminal to p and-ve terminal to
D. None of these
12
934 The electrical conductivity of a semiconductor increases when
electromagnetic radiation of wavelength shorter than 248 nm is
incident on it. The forbidden band
energy for the semiconductor in ( e V ) is
12
935 Negative feed back
A . increases stability
B. decreases stability
c. produces oscillation
D. stops current in the tube
12
936 Applying forward bias in p-njunction, the potential barrier
A. increases
B. decreases
c. remains unchanged
D. becomes zero
12
937 Consider the junction diode as ideal The value of current flowing through
( A B ) is
в. ( 10^{-2} A )
c. ( 10^{-1} A )
D. ( 10^{-3} A )
12
938 If voltage across zener diode is ( 6 V ) then
find out value of maximum resistance
in this condition.
( A cdot 2 k Omega )
3. ( 1 k Omega )
( c .5 k Omega )
D. ( 4 k Omega )
12
939 What are conductors and insulators?
Give examples.
12
940 Among the following which one gives
output 1 in the AND gate.
A. ( A=0, B=0 )
в. ( A=1, B=1 )
c. ( A=1, B=0 )
D. ( A=0, B=1 )
12
941 Identify the mismatched pair from the following
A. zener diode : voltage regulator
B. germanium doped with phosphorous : n-type semiconductor
C. semiconductor: band gap > 3 eV
D. p-n junction diode : rectifier
E. silicon doped with aluminium : p-type semiconductor
12
942 A transistor is essentially
A. a current operated device
B. power driven device
C . a voltage operated device
D. resistance operated device
12
943 How many electrodes are there in PNP or NPN transistor?
( A cdot 3 )
B.
( c cdot 2 )
( D )
12
944 In the forward bias characteristic curve,
a diode appears as:
A. an OFF switch
B. a high resistance
c. an on switch
D. a capacitor
12
945 In reverse bias, pn-junction diode
depletion layer width:
A. decreases
B. increases
c. remains same
D. can’t predict
12
946 A circuit of logic gates given below, some input signal ( A, B, C ) are given with their output signal ( x, y ) and ( z ) is given in respective option, choose correct
options:

This question has multiple correct options
A. If ( A=1, B=1, C=1 ) then ( x=0, y=1, z=1 )
B. If ( A=0, B=0 ) and ( C=1 ) then ( x=1, y=0, z=1 )
c. If ( A=0, B=0 ) and ( C=1 ) then ( x=1, y=0, z=0 )
D. If OR gate is replaced by NOR gate then net output signal of the circuit becomes ( z=0 ) for the input ( A= ) ( 0, B=0 ) and ( C=1 )

12
947 In the diagram, section A represents:
( C )
( D )
A. N-type germanium
B. P-type germanium
C. Anode
D. Diode
12
948 If the wavelength of light emitted when an electron fall from the first excited
state to the ground state are ( lambda ), the wavelength of emitted radiation when an electron fall from meta-stable state
to the ground state will be
A. greater than ( lambda )
B. less than ( lambda )
( c cdot lambda )
D. cannot be determined
12
949 Draw the circuit diagram of a full wave
rectifier and state how it works.
12
950 Figure shows a diode connected to an
external resistance and a battery.
Assuming the barrier potential developed in the diode to be ( 0.5 mathrm{V} ), find the value of current in the circuit in ( mathrm{mA} )
12
951 Diode
11. A sinusoidal voltage of rms
value 200 V is connected
to the diode and capacitor ) RMS
© 200 Volt
C in the circuit shown so
that half-wave rectification
occurs. The final potential
difference in volt, across C, is
(a) 500
(b) 200
(c) 283
(d) 141
m
12
952 With the help of necessary circuit diagram, explain the working of a photodiode used for detecting optical signals. 12
953 The band structure determines the
behaviour of a solid
A. chemical
B. electrical
c. mechanical
D. molecular
12
954 How does the energy gap of an intrinsic semiconductor vary, when doped with a trivalent impurity? 12
955 Write any three distinctions between ( p ) type and n-type semiconductor 12
956 The energy band diagrams for three
semiconductor sample of silicon are
shown. It follows that.
A. Sample X is undoped while samples Y and Z have been doped with a third group and a fifth group impurity respectively
B. Sample X is undoped while both samples Y and Z have been doped with a fifth group impurity
c. Sample X has been doped with equal amounts of third and fifth group impurities while samples ( Y ) and ( z ) are undoped
D. Sample X is undoped while samples Y and Z have been doped with a fifth group and a third group impurity respectively
12
957 The energy bands are present only when
the substance is present in the solid
state.
A. True
B. False
12
958 What are Intrinsic and Extrinsic semi-
conductors?
12
959 Integrated circuit is defined as:
A. a single electronic circuit on a small plate of semiconductor material.
B. a set of electronic circuits on one small plate of semiconductor material.
C . a circuit capable of generating dc currents.
D. a plate of semiconductor material used to connect external multiple circuits
12
960 Which of the following represents NAND
gate?
( A )
B.
( c )
( D )
12
961 A transistor has ( alpha=0.95 . ) If the emitter
current is ( 10 m A ), then the collector
current will be
A . ( 9.5 mathrm{mA} )
в. ( 10 mathrm{mA} )
c. ( 0.95 mathrm{mA} )
D. ( 95 mathrm{mA} )
12
962 An intrinsic semiconductor at the
absolute zero temperature
A. behaves like a metallic conductor
B. behaves like an insulator
c. has a large number of holes
D. has a large number of electrons
12
963 The electron density of intrinsic semiconductor at room temperature is ( 10^{16} m^{-3} . ) When doped with a trivalent impurity, the electron density is decreased to ( 10^{14} m^{-3} ) at the same
temperature. The majority carrier density is:
A ( cdot 10^{16} m^{-3} )
В. ( 10^{18} m^{-3} )
( mathbf{c} cdot 10^{21} m^{-3} )
D. ( 10^{20} mathrm{m}^{-3} )
E ( .10^{19} m^{3} )
12
964 State whether given statement is True or False

Resistivity of semiconductor depends on atomic nature of semiconductor.
A. True
B. False

12
965 Draw the circuit arrangement for
studying the ( V_{I} ) characteristics of a p-n
junction diode in reserve bias. Plot the
( V-I ) characteristics in this case.
12
966 A semiconductor has equal number of
electron and hole concentration of ( 2 times )
( 10^{8} m^{-3} . ) On doping with a certain
impurity, the electron concentration increases to ( 4 times 10^{10} m^{-3} ), then the new
hole concentration of the
semiconductor is
A ( cdot 10^{6} m^{-3} )
B. ( 10^{8} m^{-3} )
c. ( 10^{10} m^{-3} )
D. ( 10^{12} m^{-3} )
12
967 A transistor has ( alpha=0.95 . ) If the emitter
current is ( 10 mathrm{m} A ), the base current will
be
A. ( 0.1 mathrm{mA} )
в. ( 0.2 mathrm{mA} )
( c .0 .3 m A )
D. ( 0.5 mathrm{mA} )
12
968 Holes are charge carriers in
This question has multiple correct options
A. intrinsic semiconductors
B. ionic solids
C. p-type semiconductors
D. metals
12
969 Filter circuit
A. eliminates a.c. component
B. eliminates d.c. component
c. does not eliminate a.c. component
D. None of these
12
970 Assuming that the two diodes ( D_{1} ) and
( D_{2} ) used in the electric circuit shown in
the figure are ideal, find out the value of
the current flowing through ( 1 Omega ) resistor
12
971 In the half wave rectifier circuit
operating from 50 ( boldsymbol{H} boldsymbol{z} ) mains frequency, the fundamental frequency in the ripple would be
( mathbf{A} cdot 2.5 H z )
B. ( 50 mathrm{Hz} )
c. ( 70.7 H z )
D. ( 100 H z )
12
972 Explain using circuit diagram the working of ( n ) -p-n transistor as ( mathrm{CE} ) amplifier. Hence obtain expression for
its voltage gain in common emitter configuration.
12
973 Diffusion current in a p-njunction is greater than the drift current in
magnitude
A. if the junction is forward-biased
B. if the junction is reverse-biased
c. if the junction is unbiased
D. in no case
12
974 In a forward-biased photo-diode with increase in incident light intensity, the diode current:
A . increases
B. remains constant
c. decreases
D. none of the above
12
975 15. The logic circuit below has the input waveforms A and B
as shown. Pick out the correct output waveform.
Y
Input AG
Input B-
(a) ITAL
() –
©_4A
HUF
(AIEEE 2009)
12
976 Write the truth table for a NAND gate
connected as given in Figure.
12
977 The free electron density is more in
A. Conductors
B. Insulators
c. Semi conductors
D. Electrolytes
12
978 An LED operates under which biasing condition?
A. Forward bias
B. Reverse bias
c. can operate both in forward and reverse bias
D. No biasing is required
12
979 Conventional flow of current will always be from –
A. p type ( rightarrow ) n type
B. n type ( rightarrow ) p type
c. ( n ) Type ( rightarrow ) n type
D. None of these
12
980 A full wave rectifier circuit along with
the input and output are shown in the figure. The contribution from the diode
( mathbf{1} ) is are
A. ( C )
в. ( A, C )
( c cdot B & D )
D. ( A, B, C, D )
12
981 13. Let np and n, be the number of holes and conduction
electrons, respectively, in a semiconductor. Then
(a) np>n in an intrinsic semiconductor
(b) np = n, in an extrinsic semiconductor
(c) np = n, in an intrinsic semiconductor
(d) n. > np in an intrinsic semiconductor
12
982 In a n-p-n transistor, the collector current is ( 10 mathrm{mA} ). If ( 10 % ) of the electrons
are lost in the base, then the emitter current is:
A . ( 10 mathrm{mA} )
B. ( 0.9 mathrm{mA} )
c. ( 0.09 mathrm{mA} )
D. ( 11.1 mathrm{m} )
12
983 (a) Draw the circuit diagram for
studying the characteristics of a
transistor in common emitter
configuration. Explain briefly and show how input and output characteristics are drawn.
(b) The figure shows input waveform ( A )
and ( mathrm{B} ) to a logic. Draw the output
waveform for an OR gate. Write the truth
table for this logic gate and draw its logic symbol.
12
984 What is a rectifier? With the help of a neat circuit diagram explain the working of a full wave rectifier. 12
985 characteristic for a semiconductor
device. Which of the following
statement is correct?
A. It is V-I characteristic for solar cell where, point represents open circuit voltage and point B short
circuit current
B. It is for a solar cell and points A and B represent open circuit voltage and current, respectively
C. It is for a photodiode and points ( A ) and ( B ) represent open circuit voltage and current respectively
D. It is for a LED and points A and B represent open circuit voltage and short circuit current, respectively
12
986 Phosphorus which is used as an impurity to produce an extrinsic semiconductor is a ( _{-}- ) – impurity.
A. Trivalent
B. Divalent
c. Tetravalent
D. Pentavalent
12
987 Write the full name of LED. 12
988 Distinguish between ‘intrinsic’ and
extrinsic’ semiconductors.
12
989 Two identical p-njunctions may be connected in series with battery in
three ways as shown in the adjoining
figure. The potential drop across the p-n junctions are equal in
A. Circuit 1 and circuit 3
B. Circuit 1 and circuit 2
c. circuit 2 and circuit 3
D. circuit 2 only
12
990 The change in output voltage is approximately:
( mathbf{A} cdot 0.8 mu V )
в. ( 2 m V )
( mathrm{c} .3 .2 mathrm{V} )
( mathbf{D} cdot 80 mu V )
12
991 Assertion
NAND is a universal gate.
Reason
It can be used to describe all other logic
gates.
A. Both Assertion and Reason are correct and Reason is
the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is
not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Assertion is incorrect but Reason is correct
12
992 Three amplifier stages each with a gain of 10 are cascaded. The overall gain is
A . 10
B. 30
( c .1000 )
D. 100
12
993 Consider the following statements A and ( mathrm{B} ) and identify the correct answer. Statement(A):A Zener diode is always
connected in reverse bias to use it as
voltage Statement(B):The potential barrier of a p-njunction lies between 0.1 to ( 0.3 V )
approximately.
A. A and B are correct
B. A and B are wrong
c. A is correct but B is wrong.
D. A is wrong but B is correct.
12
994 The forbidden energy band gap in
conductors
12
995 An incandescent lamp is operated at
( 240 V ) and the current is ( 0.5 A . ) What is
the resistance of the lamp?
12
996 The circuit shown given contains two
ideal diodes, each with a forward
resistance of ( 50 Omega ). If the battery voltage
is ( 6 mathrm{V} ), the current through the ( 100 Omega ) resistance (in Amperes) is?
A .0 .027
В. 0.020
( c .0 .030 )
D. 0.036
12
997 A logic gate which has an output’ ( 1^{prime} )
only when the inputs are complement to
each other is.
A. AND
B. NAND
c. Nor
D. EXOR
12
998 What is Solar Panel? Write its main
three uses.
12
999 Two constant parallel forces act on a
wheel provided in a transistor for
tunning as shown in the figure. If the
wheel rotates then the work done per
rotation will be
A. 0.05 joule
B. 0.0015 joule
c. 0.031 joule
D. 0.062 joule
12
1000 A semiconductor at ( 0 K ) behaves as :
A. conductor
B. insulator
c. super conductor
D. extensive semiconductor
12
1001 Which of the following is a
characteristic of analog ICs?
A. They can be used for analog input and output signals only.
B. They cannot be used for analog input and output signals
C. Input signal is analog but output signal is digital.
D. Output signal is analog but input signal is digital.
12
1002 A transistor is operated in common-
emitter configuration at ( V_{C}=2 V ) such
that a change in the base current from
( 100 mu A ) to ( 200 mu A ) produces a change in the collector current from ( 5 mathrm{mA} ) to 10
mA. The current gain is :
A . 50
B. 75
( c cdot 100 )
D. 150
12
1003 For a transistor, ( alpha_{d c} ) and ( beta_{d c} ) are the
current ratios, then the value of ( frac{beta_{d c}-alpha_{d c}}{alpha_{d c} cdot beta_{d c}} ) is
A . 1
в. 1.5
( c cdot 2 )
D. 2.5
12
1004 The given truth table is for
( begin{array}{lll}text { Input } & text { Input } & text { Output } \ mathrm{A} & mathrm{B} & mathrm{Y} \ 0 & 0 & 1 \ 0 & 1 & 1 \ 1 & 0 & 1 \ 1 & 1 & 0end{array} )
A. AND gate
B. OR gate
C. NAND gate
D. NOR gate
12
1005 Which of the following statements is true for a p-n-p transistor when used in an amplifier circuit?
A. Emitter is connected to negative terminal of a battery
B. Base current is always lower than emitter current
c. collector is connected to positive terminal of a battery
D. collector current is always more than the emitter current
12
1006 In half-wave rectification, what is the
output frequency if the input frequency
is ( 50 H z )

What is the output frequency of a fullwave rectifier for the same input
frequency.

12
1007 In the figure shown which one is correct
diagram for LED?
(b)
(c)
da
( A cdot b )
B.
( c )
D.
12
1008 When an external voltage ( V ) is applied across a semiconductor diode such
that ( p- ) side is connected to the positive
terminal of the battery and ( n- ) side to the negative terminal, it is said to be
( A ). reverse biased.
B. forward biased
c. bias free.
D. None of these
12
1009 A Ge specimen is doped with Al. The
concentration of acceptor atom is ( sim )
( 10^{21} ) atoms ( / m^{3} . ) Given that the intrinsic
concentration of electron hole pairs is ( sim 10^{19} / m^{3} . ) The concentration of
electrons in the specimen is??
( mathbf{A} cdot 10^{17} / m^{3} )
B . ( 10^{15} / m^{3} )
c. ( 10^{4} / m^{3} )
D. ( 10^{2} / m^{3} )
12
1010 Write the logic symbol and truth table of NAND gate. 12
1011 A p-type semiconductor is made from a silicon specimen by doping on a
average one indium atom per ( 5 times 10^{7} )
silicon atoms. If the number density of
atoms in the silicon specimen is ( 5 times ) ( 10^{26} ) atoms ( / m^{3}, ) then the number of
acceptor atoms in silicon per cubic centimeter will be:
A ( .2 .5 times 10^{30} )
В. ( 1.0 times 10^{13} )
c. ( 1.0 times 10^{15} )
D. ( 2.5 times 10^{36} )
12
1012 Select one donor impurity among the following:
Boron ( (B), ) Aluminium ( (A l), ) and Arsenic ( (A s) )
12
1013 Explain avalanche breakdown in a diode and zener breakdown in a zener diode 12
1014 Assertion
A transistor amplifier in common emitter configuration has a low input impedance.
Reason
The base to emitter region is forward
biased.
A. Assertion is true, Reason is true; Reason is a correct explanation for Assertion
B. Assertion is true, Reason is true; Reason is not a correct explanation for Assertion
c. Assertion is true, Reason is false
D. Assertion is false, Reason is true
12
1015 Assertion
An AND gate is a universal gate.
Reason
The boolean expression for AND gate is
( A cdot B=C )
A. Both Assertion and Reason are correct and Reason is
the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is
not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Assertion is incorrect but Reason is correct
12
1016 Application of a forward bias to a ( mathrm{p}-mathrm{n} )
junction
A. widens the depletion zone
B. increases the potential difference across the depletion
zone
C. increases the number of donors on the n side
D. increases the electric field in the depletion zone.
12
1017 Which of the statements given is true for p-type semiconductors
(a) Electrons are majority carriers and trivalent atoms are the dopants.
(b) Electrons are minority carriers and pentavalent atoms are the dopants.
(c) Holes are minority carriers and pentavalent atoms are the dopants.
(d) Holes are majority carriers and trivalent atoms are the dopants.
12
1018 An n-type semiconductor is
A. Neutral
B. Positively charged
C . Negatively charged
D. Negatively or positively charged depending on the amount of impurity added
12
1019 The intrinsic charge carrier density in germanium crystal at ( 300 K i s 2.5 times ) ( 10^{13} / mathrm{cm}^{3} . ) density in an n-type
germanium crystal at ( 300 mathrm{K} ) be ( 5 times )
( 10^{16} / c m^{3}, ) the hole density in this n-type
crystal at ( 300 mathrm{K} ) would be
A ( cdot 2.5 times 10^{13} / mathrm{cm}^{3} )
В. ( 5 times 10^{6} / c m^{3} )
c ( cdot 1.25 times 10^{10} / mathrm{cm}^{3} )
D. ( 0.2 times 10^{4} / c m^{3} )
12
1020 For common emitter configuration of a
transistor, the collector voltage ( V_{c}= )
( 2 V ) and, base current changes from
( 100 mu A t o 200 mu A, ) and collector
current changes from ( 5 mathrm{mA} ) to ( 10 mathrm{mA} ) The current gain is
A . 100
B. 25
( c cdot 125 )
D. 50
12
1021 Assertion
The number of electrons in a p-type
silicon semiconductor is less than the
number of electrons in a pure silicon semiconductor at room temperature
Reason
It is due to law of mass action.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
1022 The following one represents logic addition is
A. ( 1+1=2 )
B. ( 1+1=10 )
c. ( 1+1=1 )
D. ( 1+1=11 )
12
1023 A A ratery is cumectuatuss AD as
shown in the figure. The value of the current supplied by the battery when in one case, battery’s positive terminal is connected to A and in other case when
positive terminal of battery is connected to B will respectively be
в. ( 0.1 A ) and ( 0.2 A )
c. 0.2 A and 0.4 A
D. ( 0.4 mathrm{A} ) and ( 0.2 mathrm{A} )
12
1024 The circuit has two oppositely
connected ideal diodes in parallel. The
current flowing in the circuit is
A . ( 1.71 A )
B. ( 2.00 A )
c. ( 2.31 A )
D. ( 1.33 A )
12
1025 Consider a p-njunction as a capacitor, formed with ( p ) and ( n ) material acting as thin metal electrodes and depletion layer width acting as separation between them. Based on this,
assume that an n-p-n transistor is working as a amplifier in CE
configuration. If ( C_{1} ) and ( C_{2} ) be base-
emitter and collector-emitter
junction capacitances, then
A ( cdot C_{1}>C_{2} )
B. ( C_{1}<C_{2} )
( mathbf{c} cdot C_{1}=C_{2} )
( mathbf{D} cdot C_{1}=C_{2}=0 )
12
1026 The bond in semiconductors is :
A. covalent
B. ionic
c. metallic
D. hydrogen
12
1027 Q Type your question
( mathbf{A} )
( B )
( mathbf{c} )
D.
12
1028 Show on a graph, the variation of
resistivity with temperature for a typical semiconductor.
12
1029 The given circuit has two ideal diodes
connected as shown in the figure below
The current flowing through the
resistance ( boldsymbol{R}_{mathbf{1}} ) will be
A ( .3 .13 A )
B . ( 2.5 A )
c. ( 10.0 A )
D. ( 1.43 A )
12
1030 When the input of a two input logic gate are 0 and ( 0, ) the output is ( 1 . ) When the inputs are 1 and 0 , the output is zero. The type of logic gate is
A. xor
B. NAND
c. NOR
D. or
12
1031 The arrangement shown in the figure
performs the logic function of
A. AND gate
B. NAND gate
c. or gate
D. XOR gate
12
1032 The circuit given below represents which of the logical operations?
( A cdot A N D )
в. NOT
( c . ) ов
D. NOR
12
1033 Explain with a neat diagram, how a p-n junction diode is used as a half wave rectifier. 12
1034 The electrical circuit used to get
smooth D.C output from a rectifier circuit is called:
( mathbf{A} ). Filter
B. Oscillator
c. ( operatorname{cogic} ) gates
D. Amplifier
12
1035 When a p-njunction diode is reverse
biased
A. electrons and holes are attracted towards each other and move towards the depletion region
B. electrons and hole move away from the junction depletion region.
C. height of the potential barrier decreases.
D. no change in the current takes place.
12
1036 How can electrical conductivity of metals, insulator and semiconductors
be explained qualitatively?
12
1037 The input of ( A ) and ( B ) for the Boolean
expression ( (overline{boldsymbol{A}+boldsymbol{B}}) cdot(overline{boldsymbol{A} cdot boldsymbol{B}})=mathbf{1} ) is
A . 0,0
в. 0,1
( c .1,0 )
D. 1,1
12
1038 The value of the resistor, ( boldsymbol{R}_{S}, ) needed in
the DC voltage regulator circuit shown
here, equals
A ( cdot frac{left(V_{i}+V_{L}right)}{(n+1) I_{L}} )
B. ( frac{left(V_{i}-V_{L}right)}{n I_{L}} )
c. ( frac{left(V_{i}+V_{L}right)}{n I_{L}} )
D. ( frac{left(V_{i}-V_{L}right)}{(n+1) I_{L}} )
12
1039 Which of the following is/ are correct
concerning “The working principle of
LED”?
This question has multiple correct options
A. electrons travel from the n-type to the p-type and holes in the opposite direction
B. n-type silicon has extra electrons to combine with the extra holes of p-type silicon
C. p-type silicon has extra electrons to combine with the extra holes of n-type silicon
D. Both A and C
12
1040 The value indicated by Fermi energy
level in an intrinsic semiconductor is
A. the average energy of electrons and holes.
B. the energy of electrons in conduction band
C. the energy of holes in valence band
D. the energy of forbidden region
12
1041 A thermistor:
A. Is a thermally sensitive resistor
B. Is made of a semiconductor
C. Has negative temperature coefficient of resistance
D. All the above
12
1042 5. A solid which is not transparent to visible light and whose
conductivity increases with temperature is formed by
(a) van der Waals binding (b) metallic binding
(c) ionic binding
(d) covalent binding
(AIEEE 2006)
12
1043 For the given combination of gates, if
the logic states of inputs ( A, B, C ) are as
follows ( boldsymbol{A}=boldsymbol{B}=boldsymbol{C}=mathbf{0} ) and ( boldsymbol{A}=boldsymbol{B}= )
( 1, C=0 ) then the logic states of
output D are
A. 0,0
B. 0,1
( c cdot 1,0 )
D. 1
12
1044 What is optoelectronic junction
devices? Write any two names of optoelectronic junction devices.
12
1045 32. Which of the following statements is incorrect?
CO
Ed
(b)
(a) The energy gap is larger in Si than in Ge
(b) The density of Ge is over 2 times that of Si
(c) A npn transistor is represented by the symbol shown
in Figure (a).
(d) A diode is represented by the symbol shown in
Figure (b).
12
1046 For a CB amplifier current gain is ( 0.54 . ) I the emitter current is ( 6.8 m A ), the
collector current will be
A . ( 1.7 mathrm{mA} )
в. ( 2.7 mathrm{mA} )
( c .3 .7 m A )
D. ( 4.7 mathrm{mA} )
12
1047 In an unbiased ( n ) -p junction electrons diffuse from n-region to p- region because
A. electrons travel across the junction due to potential difference
B. electrons concentration in n region is more as compared to that in p-region
c. holes in p-region attract them.
D. only electrons move from n- to p- region and not the vice-versa.
12
1048 For detecting the
light
A. The photodiode has to be forward biased
B. The photodiode has to be reversed biased
C. The LED has to connected in forward bias mode
D. The LED has to be connected in reverse bias mode
12
1049 10 12
1050 In a metal, the separation between conduction band and valence band is of
the order
A . 100 eV
B. 10 eV
( c cdot 0 e V )
D. 1 eV
12
1051 At what temperature semiconductors behaves as an ideal insulator?
A. ( 273.15^{circ} mathrm{C} )
B . -459.67 ॰ ( F )
c. ( -273^{circ} F )
D. Room temperature
12
1052 Qoppr
5
s.
( ” )
“.
12
1053 Energy gap of conductor is
A. 0 eV
в. 1 eV
( c cdot 2 e V )
D. 3 eV
12
1054 Fill in the blank.
The following truth table with ( A ) and ( B )
as inputs is for ( _{-}- ) gate.
( begin{array}{lll}text { A } & text { B } & text { Output } \ & & \ 1 & text { 0 } & 1 \ text { 1 } & 1 & text { 0 } \ text { 0 } & 1 & 1 \ text { 0 } & text { 0 } & text { 0 }end{array} )
A. AND
B. OR
c. хок
D. NOR
12
1055 40. In question 38, the transconductance in 2′ is
(a) 0
(b) 0.2
(c) 0.1
(d) 0.05
:
12
1056 What are the essential components of an oscillator? Draw its block diagram? 12
1057 Assertion
A photocell is called an electric eye.
Reason
When light is incident on some
semiconductor its electrical resistance
is reduced
A. Both Assertion and Reason are correct and Reason is
the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
1058 Q Type your question
B
( c )
( D )
12
1059 A graph of the output from an A.C.
generator is given. This is given as:
(a) an input to a half wave rectifier
(b) an input to a full wave rectifier Give graphic representations of the outputs in the cases (a) and (b).
12
1060 The gate whose output is low if and only if all inputs are high, is
A. NAND
B. AND
( c . ) ов
D. None of these
12
1061 What is the conductivity of a semiconductor sample having electron concentration of ( 5 times 10^{18} quad m^{-3}, ) hole
concentration of ( 5 times 10^{19} quad m^{-3} )
electron mobility of ( 2.0 m^{2} v^{-1} s^{-1} ) and
hole mobility of ( 0.01 m^{2} v^{-1} s^{-1} ? )
(Take charge of electron as ( 1.6 times )
( left.10^{-19} Cright) )
A ( cdot 1.68(Omega-m)^{-1} )
в. ( 0.59(Omega-m)^{-1} )
c. ( 1.83(Omega-m)^{-1} )
D. ( 1.20(Omega-m)^{-1} )
12
1062 A diode is connected to the output of a transformer as shown in the figure given below. Analyse the figure.
a) Draw a time-voltage graph for the current obtained across AB.
b) What is the function of the diode in
the circuit?
12
1063 State True or False:
Saturation current depends on
temperature.
A. True
B. False
12
1064 A piece of copper and another of germanium are cooled from room temperature to ( 80 mathrm{K} ). The resistance of:
A. each of them increases
B. each of them decreases
c. copper increases and germanium decreases
D. copper decreases and germanium increases.
12
1065 The ( 6 V ) Zener diode is shown in figure
has negligible resistance and a knee
current of ( 5 m A ). The minimum value of
( R(i n Omega) ) so that the voltage across it
does not fall below ( 6 V ) is
A. 40
в. 60
( c cdot 72 )
D. 80
( E .120 )
12
1066 A pnjunction conducts only in forward biased condition.
A. True
B. False
12
1067 Application of a forward bias to a ( mathrm{p}-mathrm{n} )
junction
A. widens the depletion zone
B. increases the potential difference across the depletion
zone
C. increases the number of donors on the n side
D. increases the electric field in the depletion zone
12
1068 An LED is forward-biased. The diode
should be on, but no light is showing. A possible trouble might be :
A. the diode is open.
B. the series resistor is too small
c. the power supply voltage is too high.
D. none of these
12
1069 Figure shows a full wave bridge rectifier
circuit. The input a.c. is connected
across
( A cdot A ) and ( B )
B. A and C
C. ( B ) and ( D )
D. ( B ) and ( C )
12
1070 In an experiment of photoelectric effect the number of photoelectrons has to be increased without changing their frequency. The suitable step to be taken about the incident radiation for this is
A. increasing intensity without changing frequency
B. increase both frequency and intensity
C. increase frequency without increasing intensity
D. increasing only frequency
12
1071 For the given circuit of ( boldsymbol{p}-boldsymbol{n} ) junction,
the potential barrier is :
A. Raised
B. Lowered
c. Remains same
D. Data insufficient
12
1072 There photo dlodes ( D_{1}, D_{2} ) and ( D_{3} ) are made of semiconductor having band
( operatorname{gap} 2.5 e V, 2 e V ) and ( 3 e V ) respectively. Which one will be able to detect light of
wavelength ( 6000 A^{circ} ? )
A. ( D_{1} )
в. ( D_{2} )
( c cdot D_{3} )
D. ( D_{1} ) and ( D_{2} ) both
12
1073 In a half wave rectifier, the output is
taken across a ( 90 Omega ) load resistor. If the resistance of diode in forward biased
condition is ( 10 Omega ), the efficiency of rectification of ac power into dc power is
A . ( 40.6 % )
B. ( 81.2 % )
c. ( 73.08 % )
D. ( 36.54 % )
12
1074 A change of ( 200 m V ) in base-emitter
voltage causes a change of ( 100 mu A ) in
the base current. The input resistance of the transistor is
( mathbf{A} cdot 2 K Omega )
в. ( 2 Omega )
c. ( 2 m Omega )
D. 10 KOmega
12
1075 State whether true or false:
The highest occupied energy band is called the valence band and the lowest
unoccupied energy band is called the conduction band.
A. True
B. False
12
1076 In intrinsic semiconductors:
( mathbf{A} cdot n>p )
В. ( p>n )
c. ( n=p )
D. ( n=0 )
12
1077 The colour of light emitted by LED depends on
A. Its reverse bias
B. The amount of forward current
c. Its forward bias
D. Type of semiconductor material
12
1078 When all the inputs of a NAND gate are connected together, the resulting circuit is:
A . a NOT gate
B. an AND gate
c. an OR gate
D. a NOR gate
12
1079 A full wave p-n diode rectifier uses a
load resistance of ( 1300 Omega ). No filter is
used. If the internal resistance of each
diode is ( 9 Omega ), then the efficiency of this full wave rectifier is
A. ( 80.64 % )
B . ( 40.6 % )
c. ( 13.9 % )
D. ( 100 % )
12
1080 ( sqrt{ }rceil )
( Gamma )
begin{tabular}{r}
( pi ) \
hline
end{tabular}
12
1081 Two PN junctions can be connected in series by three
different methods as shown in the figure. If the potential
difference in the junctions is the same, then the correct
connections will be
PNP
PINPINA MPANPA
(a) in circuits (1) and (2)
(c) in circuits (1) and (3)
(b) in circuits (2) and (3)
(d) only in circuit (1)
12
1082 A junction transistor does not have a/an
A. emitter-base junction
B. base-collectorjunction
c. emitter-collector junciton
D. none of the above
12
1083 The value of current in the above
diagram is (diode assumed to be ideal one)
A. ( 0.1 A )
B. ( 0.01 A )
( c .1 A )
( D )
12
1084 Select the correct statement from the
following:
A. A diode can be used as a rectifier
B. A triode cannot be used as a rectifier
C. The current in a diode is always proportional to the applied voltage
D. The linear portion of the I-V characteristic of a triode is used for amplification without distortion
12
1085 For given logic diagram, output ( boldsymbol{F}=mathbf{1} )
then inputs are:
( mathbf{A} cdot A=0, B=0, C=0 )
( mathbf{B} cdot A=0, B=1, C=0 )
( mathbf{c} cdot A=1, B=1, C=1 )
( mathbf{D} cdot A=0, B=0, C=1 )
12
1086 The truth table given below is for (A and B are the inputs, ( Y ) is the output)
( A B Y )
001
011
101
110
A. NOR
B. AND
c. хок
D. NAND
12
1087 In a diode, when there is a saturation
current, the plate resistance will be
A. data insufficient
B. zero
c. some finite quantity
D. infinite
12
1088 Which of the following is not the function of a NOT gate?
A. Stop a signal.
B. Invert an input signal
c. complement a signal.
D. change the logic in a digital circuit
12
1089 A NOR gate and a NAND gate are
connected as shown in the figure. Two different sets of inputs are given to this set up. In the first case, the input to the
gates are ( A=0, B=0, C=0 . ) In the second
case, the inputs are ( A=1, B=0, C=1 . ) The output D in the first case and second case respectively are
A. 0 and 0
B. O and 1
c. 1 and 0
D. 1 and 1
12
1090 Find the maximum zener current for the
zener diode as shown in figure. Given,
( boldsymbol{V}_{Z}=mathbf{6} boldsymbol{V}, boldsymbol{R}_{Z}=mathbf{1 . 5 Omega}, boldsymbol{R}=mathbf{4 0 0 Omega} )
A. ( 35.00 mathrm{mA} )
в. ( 30.87 m A )
( c .34 .87 m A )
D. ( 34.87 A )
12
1091 Arrange the following in decreasing order of their Band gaps
A. conductors, , Insulators, Semiconductors
B. Insulators, Semiconductors, Conductors
c. Insulators, Conductors, Semiconductors
D. conductors, Semiconductors, Insulators
12
1092 How will you obtain OR, AND gates from
the NAND and NOR gates? Write symbol, Boolean formula and truth table.
12
1093 In n-type semiconductor, the Fermi
level is present:
A. just below the valence band
B. just below the conduction band
C. just above the valence band
D. in the middle of valence and conduction bands
12
1094 A p-n photodiode is fabricated from a
semiconductor with band gap of ( 2.8 e V )
Can it detect a wavelength of 6000 nm?
12
1095 Distinguish between Avalanche breakdown and Zener breakdown. 12
1096 In half-wave rectification, what is the
output frequency if the input frequency
is ( 50 H z )

What is the output frequency of a fullwave rectifier for the same input
frequency.

12
1097 8. Reverse bias applied to a junction diode
(a) lowers the potential barrier
(b) raises the potential barrier
(c) increases the majority carrier current
(d) increases the minority carrier current.
12
1098 Fill in the blanks:
When light falls on the junction of a photo diode, the number of charge carriers and hence the
conductivity of the junction
A. increases, decreases
B. decreases, increases
c. decreases, decreases
D. increases, increases
12
1099 The number of photo electrons emitted
per second depend on the
of incident radiatic.
12
1100 The value of form factor in case of half
wave rectifier is:
A . 1.11
в. 1.57
c. 1.27
D. 0.48
12
1101 The width of forbidden gap in silicon crystal is ( 1.1 e V . ) When the crystal is
converted into an n-type
semiconductor, the distance of fermi level from conduction band is
A. greater than 0.55 eV
B. equal to 0.55 eV
c. lesser than 0.55 eV
D. equal to ( 1.1 mathrm{eV} )
12
1102 The base current of a transistor is
( 105 mu A ) and the collector current is
( 2.05 m A . ) Then ( beta ) of the transistor is
( mathbf{A} cdot 1.952 )
B. 19.52
c. 195.2
D. 1952
12
1103 60. How many NAND gates are required to get a half adder.
(a) 3
(6) 5
(c) 9
Tos (d) 7 B
12
1104 In the following circuit the output ( Y )
becomes zero for the input
combinations:
( A cdot A=1, B=0, C=0 )
B. ( A=0, B=1, C=1 )
C. ( A=0, B=0, C=0 )
D. ( A=1, B=1, C=0 )
12
1105 With the help of neat labelled circuit diagram explain the working of half wave rectifier using semiconductor
diode. Draw the input and output waveforms.
12
1106 U NUNC Ul Ulese
48. The following truth table corresponds to the logic gate:
А в х
0 0 0
0
01.
(a) NAND
(C) XOR
(b) AND
(d) OR
12
1107 A photo diode is made from a
semiconductor ( I n_{0.53} . ) As, with ( E_{g}=0.73 )
eV. What is the maximum wavelength
which it can detect? ( boldsymbol{h}=mathbf{6 . 6 3} times )
( 10^{-34} J_{s} )
12
1108 The energy gap of silicon is 1.14 eV.The
maximum wavelength at which silicon starts energy absorption, will be ( left(h=6.62 times 10^{-34} J s, c=3 times 10^{8} m / sright) )
A ( cdot 10.888 AA )
B ( cdot 108.88 AA )
( c cdot 1088.8 AA )
D ( cdot 10888 ) 能
12
1109 When added an impurity into the silicon which one of the following produces ( n ) type of semi-conductors:
A. iron
B. magnesium
c. aluminium
D. phosphorous
12
1110 In semiconductor physics, what is meant by an oscillator? 12
1111 The circuit shown in the figure contains two diodes, each with a forward
resistance of ( 50 Omega ) and with infinite
backward resistance. If the battery
voltage is ( 6 mathrm{V} ), the current through the
( 100-Omega ) resistance is
A. zer
B. ( 0.02 A )
c. ( 0.04 A )
D. ( 0.046 A )
12
1112 Assertion
( mathbf{A} )
p-njunction with reverse bias can be used as a photo-diode to measure light intensity.
Reason
In a reverse bias condition the current
is small but is more sensitive to
changes in incident light intensity.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Assertion is incorrect but Reason are correct
12
1113 A transistor is a/an
A . chip
B. insulator
c. semiconductor
D. metal
12
1114 If the forward voltage in a
semiconductor is doubled, the width of
depletion layer will
A. become half
B. become one-fourth
c. remain unchanged
D. become double
12
1115 toppr
Q Type your question-
( A )
begin{tabular}{cc|c}
( boldsymbol{x} ) & ( boldsymbol{y} ) & ( boldsymbol{z} ) \
hline ( mathbf{0} ) & ( mathbf{0} ) & ( mathbf{1} ) \
( boldsymbol{0} ) & ( mathbf{1} ) & ( mathbf{1} ) \
( mathbf{1} ) & ( boldsymbol{0} ) & ( mathbf{1} ) \
( mathbf{1} ) & ( mathbf{1} ) & ( mathbf{0} )
end{tabular}
B. begin{tabular}{cc|c}
( boldsymbol{x} ) & ( boldsymbol{y} ) & ( boldsymbol{z} ) \
hline ( mathbf{0} ) & ( mathbf{0} ) & ( mathbf{0} ) \
( mathbf{0} ) & ( mathbf{1} ) & ( mathbf{0} ) \
( mathbf{1} ) & ( mathbf{0} ) & ( mathbf{0} ) \
( mathbf{1} ) & ( mathbf{1} ) & ( mathbf{1} )
end{tabular}
( c )
begin{tabular}{cc|c}
( boldsymbol{x} ) & ( boldsymbol{y} ) & ( boldsymbol{z} ) \
hline ( mathbf{0} ) & ( mathbf{0} ) & ( mathbf{1} ) \
( mathbf{0} ) & ( mathbf{1} ) & ( mathbf{1} ) \
( mathbf{1} ) & ( mathbf{0} ) & ( mathbf{1} ) \
( mathbf{1} ) & ( mathbf{1} ) & ( mathbf{1} )
end{tabular}
( D )
begin{tabular}{cc|c}
( boldsymbol{x} ) & ( boldsymbol{y} ) & ( boldsymbol{z} ) \
hline ( mathbf{0} ) & ( mathbf{0} ) & ( mathbf{0} ) \
( mathbf{0} ) & ( mathbf{1} ) & ( mathbf{1} ) \
( mathbf{1} ) & ( mathbf{0} ) & ( mathbf{1} ) \
( mathbf{1} ) & ( mathbf{1} ) & ( mathbf{1} )
end{tabular}
12
1116 A potential barrier of ( 0.50 mathrm{V} ) exists across of PN Junction. If the depletion region is ( 5.0 times 10^{-7} m ) wide, the
intensity of the electric field in this
region is
A ( cdot 1.0 times 10^{9} mathrm{V} / mathrm{m} )
в. ( 2.0 times 10^{5} mathrm{V} / mathrm{m} )
c. ( 1.0 times 10^{6} mathrm{V} / mathrm{m} )
D. 2.0 ( times 10^{6} mathrm{V} / mathrm{m} )
12
1117 ( V_{m} ) is the maximum voltage between trends of the secondary terminal of a
transformer used in a half wave
rectifier. When the PN junction diode is reverse biased, what will be the
potential difference between two ends
of the diode?
A. zero
в. ( frac{V_{m}}{2} )
c. ( V_{m} )
D. ( 2 V_{m} )
12
1118 (U) 125 V
68. In question 67, the power gain is
(a) 125 x 50 (b) 125
(c) 1.25 50
(d) 2.5 x 104
125
90
12
1119 Which of the following is a semiconductor?

This question has multiple correct options
A. Constantan
B. Porcelain
c. Germanium
D. silicon

12
1120 The electrical conductivity of a semiconductor increases when
electromagnetic radiation of
wavelength shorter than 600 nm is incident on it. The energy band gap (in
eV) for the semiconductor is
A . 1.50
в. .075
c. 2.06
D. 1.35
E . 0.90
12
1121 What is rectification? Explain the working of a fullwave rectifier. Draw necessary circuit diagram. 12
1122 A diode allows the electric current to
flow, when it is in forward bias, but if it
is in reverse bias it will not allow the
electric current to flow. Why?
12
1123 toppr ( t )
Q Type your question-
( sqrt{1} cdot frac{1}{2} )
( A )
begin{tabular}{|c|c|c|}
hline ( mathbf{A} ) & ( mathbf{B} ) & ( mathbf{Y} ) \
hline ( mathbf{0} ) & ( mathbf{0} ) & ( mathbf{0} ) \
( mathbf{1} ) & ( mathbf{0} ) & ( mathbf{0} ) \
( mathbf{0} ) & ( mathbf{1} ) & ( mathbf{0} ) \
( mathbf{1} ) & ( mathbf{1} ) & ( mathbf{1} ) \
hline
end{tabular}
в. begin{tabular}{|c|c|c|}
hline ( mathbf{A} ) & ( mathbf{B} ) & ( mathbf{Y} ) \
hline ( mathbf{0} ) & ( mathbf{0} ) & ( mathbf{0} ) \
( mathbf{1} ) & ( mathbf{0} ) & ( mathbf{1} ) \
( mathbf{0} ) & ( mathbf{1} ) & ( mathbf{1} ) \
( mathbf{1} ) & ( mathbf{1} ) & ( mathbf{1} ) \
hline
end{tabular}
( c )
begin{tabular}{|c|c|c|}
hline ( mathbf{A} ) & ( mathbf{B} ) & ( mathbf{Y} ) \
hline ( mathbf{0} ) & ( mathbf{0} ) & ( mathbf{1} ) \
( mathbf{1} ) & ( mathbf{0} ) & ( mathbf{0} ) \
( mathbf{0} ) & ( mathbf{1} ) & ( mathbf{0} ) \
( mathbf{1} ) & ( mathbf{1} ) & ( mathbf{0} ) \
hline
end{tabular}
D. begin{tabular}{|c|c|c|}
hline ( mathbf{A} ) & ( mathbf{B} ) & ( mathbf{Y} ) \
hline ( mathbf{0} ) & ( mathbf{0} ) & ( mathbf{1} ) \
( mathbf{1} ) & ( mathbf{0} ) & ( mathbf{1} ) \
( mathbf{0} ) & ( mathbf{1} ) & ( mathbf{1} ) \
( mathbf{1} ) & ( mathbf{1} ) & ( mathbf{0} ) \
hline
end{tabular}
12
1124 In the figure shown, if the diode forward
voltage drops is ( 0.2 V ), the voltage difference between ( A ) and ( B ) is
A ( .1 .3 V )
В. ( 2.2 V )
( c .0 .5 V )
( D )
12
1125 37. In question 35, the transconductance is
(a) 0.1 mho
(b) 0.2 mho
(c) 0.3 mho
(d) 0.4 mho
12
1126 Diode can work as
A. Modulator
B. Demodulator
C. Rectifier
D. Amplifier
12
1127 Which of the following semiconductor is electrically positive?
A. Intrinsic semiconductor
B. P-type semiconductor
c. N-type semiconductor
D. None of these
12
1128 Which of the following contains a covalent bond?
A. copper
в. ( N a C l )
c. germanium
D. helium
12
1129 In the Boolean Algebra A.B is same.
( A cdot A+B )
B. A-B
c. ( A-B )
D. Adivs
12
1130 What is a transistor? Why is it so
called? What are the advantages of transistors over vacuum tubes?
12
1131 61. Which circuit adds two bits P and Q to provide the corre
range of outputs for a half-adder?
(a) Po
EX-OR
Sum
AND
Carry
(b) P
EX-OR
Sum
NAND
Carry
EX-OR
Sum
OR
Carry
(d) pe
AND
Sum
EX-OR
Carry
12
1132 An amplifier has a voltage gain ( boldsymbol{A}_{boldsymbol{v}}= )
1000. The voltage gain in dB is:
( mathbf{A} cdot 30 d B )
В. ( 60 d B )
c. ( 3 d B )
( mathbf{D} cdot 20 d B )
12
1133 (a) Draw the circuit diagram of a ful
wave rectifier using ( boldsymbol{p}-boldsymbol{n} ) junction
diode

Explain its working and show the
output, input waveforms.
(b) Show the output waveforms (Y) for
the following inputs ( A ) and ( B ) of
(i) OR gate (ii) NAND gate

12
1134 The I V characteristics of solar cell is
drawn in the fourth quadrant of the
coordinate axes because
A. a solar cell does not draw current but supplies the same to the load
B. a solar cell draws current but supplies no current to the load
c. a solar cell draws voltage and supplies current to the load
D. a solar cell draws current but supplies voltage to the load
12
1135 Examples of opto-electronic devices are This question has multiple correct options
A. Light Emitting Diodes (LED)
B. Zener diode
c. Solar cells
D. Photodiodes
12
1136 How many NAND gates are needed to perform the logic function X.Y?
A . 1
B. 2
( c cdot 3 )
( D )
12
1137 ( left(A_{V}right) ) and load resistance ( left(R_{L}right) ) is :
( A )
( B )
( c )
D.
12
1138 In an insulator, band gap of the order of?
A ( .0 .1 e V )
B. ( 1 e V )
c. ( 5 e V )
D. ( 100 e V )
E . ( 1 mathrm{MeV} )
12
1139 Draw the circuit diagram of a voltage regulator using zener diode. 12

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