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Class 12 • Physics
Semiconductors and Logic Gates
Chapter-14
239 Questions
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112 Easy127 Medium
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1
Medium
Two p-n junction diodes D_{1} and D_{2} are connected as shown in figure. A and B are input signals and C is the output. The given circuit will function as a ________.
Options:
A) AND gate
B) OR gate
C) NOR gate
D) NAND gate
2
Easy
Two p-n junction diodes D_1 and D_2 are connected as shown in figure. A and B are input signals and C is the output. The given circuit will function as a ________.
Options:
A) AND Gate
B) OR Gate
C) NOR Gate
D) NAND Gate
3
Easy
Assuming in forward bias condition there is a voltage drop of 0.7 V across a silicon diode, the current through diode D_{1} in the circuit is ______ mA.\\ (Assume all diodes in the given circuit are identical)
Options:
A) 17.6
B) 18.8
C) 20.15
D) 11.7
4
Medium
Assuming in forward bias condition there is a voltage drop of 0.7 V across a silicon diode, the current through diode D_1 in the circuit is \_\_\_\_ mA . (Assume all diodes in the given circuit are identical)
Options:
A) 17.6
B) 18.8
C) 20.15
D) 11.7
5
Easy
Identify the correct truth table of the given logic circuit
Options:
A) \begin{array}{|c|c|c|}
\hline
A & B & Y \\
\hline
0 & 0 & 0 \\
\hline
0 & 1 & 0 \\
\hline
1 & 0 & 1 \\
\hline
1 & 1 & 0 \\
\hline
\end{array}
B) \begin{array}{|c|c|c|}
\hline
A & B & Y \\
\hline
0 & 0 & 0 \\
\hline
0 & 1 & 1 \\
\hline
1 & 0 & 1 \\
\hline
1 & 1 & 0 \\
\hline
\end{array}
C) \begin{array}{|c|c|c|}
\hline
A & B & Y \\
\hline
0 & 0 & 1 \\
\hline
0 & 1 & 1 \\
\hline
1 & 0 & 1 \\
\hline
1 & 1 & 0 \\
\hline
\end{array}
D) \begin{array}{|c|c|c|}
\hline
A & B & Y \\
\hline
0 & 0 & 1 \\
\hline
0 & 1 & 0 \\
\hline
1 & 0 & 1 \\
\hline
1 & 1 & 0 \\
\hline
\end{array}
6
Easy
\text { Identify the correct truth table of the given logic circuit. }
Options:
A) \begin{array}{|c|c|c|} \hline \text { A } & \text { B } & \text { Y } \\ \hline \hline 0 & 0 & 0 \\ \hline \hline 0 & 1 & 0 \\ \hline 1 & 0 & 1 \\ \hline 1 & 1 & 0 \\ \hline \end{array}
B) \begin{array}{|c|c|c|} \hline \text { A } & \text { B } & \text { Y } \\ \hline \hline 0 & 0 & 0 \\ \hline \hline 0 & 1 & 1 \\ \hline 1 & 0 & 1 \\ \hline 1 & 1 & 0 \\ \hline \end{array}
C) \begin{array}{|c|c|c|} \hline \text { A } & \text { B } & \text { Y } \\ \hline \hline 0 & 0 & 1 \\ \hline \hline 0 & 1 & 1 \\ \hline \hline 1 & 0 & 1 \\ \hline \hline 1 & 1 & 0 \\ \hline \end{array}
D) \begin{array}{|c|c|c|} \hline \text { A } & \text { B } & \text { Y } \\ \hline \hline 0 & 0 & 1 \\ \hline \hline 0 & 1 & 0 \\ \hline 1 & 0 & 1 \\ \hline 1 & 1 & 0 \\ \hline \end{array}
7
Easy
For the given logic gate circuit, which of the following is the correct truth table?
Options:
A) \begin{array}{|c|c|c|}
\hline
n & m & z \\
\hline
0 & 0 & 1 \\
\hline
0 & 1 & 0 \\
\hline
1 & 1 & 0 \\
\hline
1 & 0 & 0 \\
\hline
\end{array}
B) \begin{array}{c|c|c}
n & m & z \\
\hline
0 & 0 & 1 \\
0 & 1 & 0 \\
1 & 1 & 0 \\
1 & 0 & 0 \\
\end{array}
C) \begin{array}{|c|c|c|}
\hline
n & m & z \\
\hline
0 & 0 & 0 \\
\hline
0 & 1 & 1 \\
\hline
1 & 1 & 0 \\
\hline
1 & 0 & 1 \\
\hline
\end{array}
D) \begin{array}{|c|c|c|}
\hline
n & m & z \\
\hline
0 & 0 & 1 \\
\hline
0 & 1 & 1 \\
\hline
1 & 1 & 0 \\
\hline
1 & 0 & 0 \\
\hline
\end{array}
8
Easy
\text { For the given logic gate circuit, which of the following is the correct truth table? }
Options:
A) \begin{array}{c|c|c} n & m & z \\ \hline 0 & 0 & 1 \\ 0 & 1 & 1 \\ 1 & 1 & 0 \\ 1 & 0 & 0 \end{array}
B) \begin{array}{c|c|c} n & m & z \\ \hline 0 & 0 & 1 \\ 0 & 1 & 0 \\ 1 & 1 & 1 \\ 1 & 0 & 0 \end{array}
C) \begin{array}{c|c|c} n & m & z \\ \hline 0 & 0 & 0 \\ 0 & 1 & 1 \\ 1 & 1 & 0 \\ 1 & 0 & 1 \end{array}
D) \begin{array}{c|c|c} n & m & z \\ \hline 0 & 0 & 1 \\ 0 & 1 & 0 \\ 1 & 1 & 0 \\ 1 & 0 & 0 \end{array}
9
Medium
The following diagram shows a Zener diode as a voltage regulator. The Zener diode is rated at V_z=5 \mathrm{~V} and the desired current in load is 5 mA . The unregulated voltage source can supply upto 25 V . Considering the Zener diode can withstand four times of the load current, the value of resistor R_s (shown in circuit) should be \_\_\_\_ \Omega.
Options:
A) 100
B) 10
C) 1000
D) 4000
10
Easy
The correct truth table for the given input data of the following logic gate is :
Options:
A) Inputs
Output
A
B
C
D
Y
1
1
0
1
1
0
0
1
1
0
1
0
1
0
0
1
1
1
1
1
B) Inputs
Output
A
B
C
D
Y
1
1
0
1
0
0
0
1
1
1
1
0
1
0
1
1
1
1
1
1
C) Inputs
Output
A
B
C
D
Y
1
1
0
1
1
0
0
1
1
0
1
0
1
0
1
1
1
1
1
0
D) Inputs
Output
A
B
C
D
Y
1
1
0
1
0
0
0
1
1
0
1
0
1
0
1
1
1
1
1
1
11
Medium
Find the correct combination of \mathrm{A}, \mathrm{B}, \mathrm{C} and D inputs which can cause the LED to glow.
Options:
A) 1000
B) 0011
C) 0100
D) 1101
12
Medium
The charge stored by the capacitor C in the given circuit in the steady state is __________ µC.
Options:
A) 7.5
B) 5
C) 10
D) 12.5
13
Easy
\text { The given circuit works as : }
Options:
A) NOR gate
B) OR gate
C) AND gate
D) NAND gate
14
Easy
The output voltage in the following circuit is (Consider ideal diode case)
Options:
A) 0 V
B) +5 V
C) −5 V
D) 10 V
15
Easy
Consider the following logic circuit. The output is Y = 0 when :
Options:
A) A = 1 and B = 0
B) A = 0 and B = 0
C) A = 1 and B = 1
D) A = 0 and B = 1
16
Medium
In the following circuit, the reading of the ammeter will be ( Take Zener breakdown voltage =4 \mathrm{~V})
Options:
A) 60 mA
B) 80 mA
C) 10 mA
D) 24 mA
17
Medium
Consider a n-type semiconductor in which \mathrm{n}_{\mathrm{e}} and \mathrm{n}_{\mathrm{h}} are number of electrons and holes, respectively. (A) Holes are minority carriers (B) The dopant is a pentavalent atom (C) \mathrm{n}_{\mathrm{e}} \mathrm{n}_{\mathrm{h}} \neq \mathrm{n}_i^2 (where \mathrm{n}_i is number of electrons or holes in semiconductor when it is intrinsic form) (D) \mathrm{n}_{\mathrm{e}} \mathrm{n}_{\mathrm{h}} \geqslant \mathrm{n}_i^2 (E) The holes are not generated due to the donors Choose the correct answer from the options given below :
Options:
A) (A), (B), (E) only
B) (A), (C), (E) only
C) (A), (B), (C) only
D) (A), (C), (D) only
18
Medium
The Boolean expression \mathrm{Y}=A \bar{B} C+\bar{A} \bar{C} can be realised with which of the following gate configurations. A. One 3-input AND gate, 3 NOT gates and one 2-input OR gate, One 2-input AND gate, B. One 3 -input AND gate, 1 NOT gate, One 2 -input NOR gate and one 2 -input OR gate C. 3 -input OR gate, 3 NOT gates and one 2 -input AND gate Choose the correct answer from the options given below:
Options:
A) B, C Only
B) A, B, C Only
C) A, B Only
D) A, C Only
19
Easy
\text {The truth table corresponding to the circuit given below is: }
Options:
A) \begin{array}{|c|c|c|} \hline \mathrm{A} & \mathrm{~B} & \mathrm{C} \\ \hline 0 & 0 & 0 \\ \hline 0 & 1 & 0 \\ \hline 1 & 0 & 1 \\ \hline 1 & 1 & 1 \\ \hline \end{array}
B) \begin{array}{|c|c|c|} \hline \text { A } & \mathrm{B} & \mathrm{C} \\ \hline 0 & 0 & 1 \\ \hline 1 & 0 & 0 \\ \hline 0 & 1 & 0 \\ \hline 1 & 1 & 0 \\ \hline \end{array}
C) \begin{array}{|c|c|c|} \hline \text { A } & \mathrm{B} & \mathrm{C} \\ \hline 0 & 0 & 1 \\ \hline 0 & 1 & 0 \\ \hline 1 & 0 & 0 \\ \hline 1 & 1 & 0 \\ \hline \end{array}
D) \begin{array}{|c|c|c|} \hline \mathrm{A} & \mathrm{~B} & \mathrm{C} \\ \hline 0 & 0 & 0 \\ \hline 1 & 0 & 0 \\ \hline 0 & 1 & 0 \\ \hline 1 & 1 & 1 \\ \hline \end{array}
20
Easy
\text { Choose the correct logic circuit for the given truth table having inputs } A \text { and } B \text {. } $ Inputs Output A B Y 0 0 0 0 1 0 1 0 1 1 1 1
Options:
A)
B)
C)
D)
21
Easy
\text { In the digital circuit shown in the figure, for the given inputs the } P \text { and } Q \text { values are : }
Options:
A) P=0, Q=1
B) P=1, Q=0
C) \mathrm{P}=0, \mathrm{Q}=0
D) P=1, Q=1
22
Medium
A zener diode with 5 V zener voltage is used to regulate an unregulated dc voltage input of 25 V . For a 400 \Omega resistor connected in series, the zener current is found to be 4 times load current. The load current \left(I_L\right) and load resistance \left(R_L\right) are :
Options:
A) \mathrm{I}_{\mathrm{L}}=0.02 \mathrm{~mA} ; \mathrm{R}_{\mathrm{L}}=250 \Omega
B) \mathrm{I}_{\mathrm{L}}=10 \mathrm{~A} ; \mathrm{R}_{\mathrm{L}}=0.5 \Omega
C) \mathrm{I}_{\mathrm{L}}=10 \mathrm{~mA} ; \mathrm{R}_{\mathrm{L}}=500 \Omega
D) \mathrm{I}_{\mathrm{L}}=20 \mathrm{~mA} ; \mathrm{R}_{\mathrm{L}}=250 \Omega
23
Easy
The truth table for the circuit given below is:
Options:
A) ABY000111101011
B) ABY000101010110
C) ABY000100110011
D) ABY000011101110
24
Easy
For the circuit shown above, equivalent GATE is :
Options:
A) NOT gate
B) NAND gate
C) AND gate
D) OR gate
25
Easy
Which of the following circuits has the same output as that of the given circuit?
Options:
A)
B)
C)
D)
26
Easy
The output of the circuit is low (zero) for : (A) X=0, Y=0 (B) X=0, Y=1 (C) X=1, Y=0 (D) X=1, Y=1 Choose the correct answer from the options given below :
Options:
A) (A), (B) and (C) only
B) (A), (C) and (D) only
C) (B), (C) and (D) only
D) (A), (B) and (D) only
27
Medium
Consider the following statements : A. The junction area of solar cell is made very narrow compared to a photo diode. B. Solar cells are not connected with any external bias. C. LED is made of lightly doped p-n junction. D. Increase of forward current results in continuous increase of LED light intensity. E. LEDs have to be connected in forward bias for emission of light. Choose the correct answer from the options given below :
Options:
A) A, C, E Only
B) B, E Only
C) A, C Only
D) B, D, E Only
28
Easy
What is the current through the battery in the circuit shown below?
Options:
A) 1.5 A
B) 0.25 A
C) 1.0 A
D) 0.5 A
29
Medium
Refer to the circuit diagram given in the figure. which of the following observations are correct? A. Total resistance of circuit is 6 \Omega B. Current in Ammeter is 1 A C. Potential across A B is 4 Volts. D. Potential across CD is 4 Volts E. Total resistance of the circuit is 8 \Omega. Choose the correct answer from the options given below:
Options:
A) B, C and E Only
B) A, C and D Only
C) A, B and C Only
D) A, B and D Only
30
Easy
To obtain the given truth table, following logic gate should be placed at G :
Options:
A) NOR Gate
B) OR Gate
C) AND Gate
D) NAND Gate
31
Easy
Which of the following circuits represents a forward biased diode? Choose the correct answer from the options given below:
Options:
A) (C) and (E) only
B) (A) and (D) only
C) (B), (D) and (E) only
D) (B), (C) and (E) only
32
Easy
In the truth table of the above circuit the value of X and Y are :
Options:
A) 1, 1
B) 0, 1
C) 1, 0
D) 0, 0
33
Easy
The $I-V$ characteristics of an electronic device shown in the figure. The device is :
Options:
A) a solar cell
B) a transistor which can be used as an amplifier
C) a diode which can be used as a rectifier
D) a zener diode which can be used as a voltage regulator
34
Easy
A light emitting diode (LED) is fabricated using GaAs semiconducting material whose band gap is $1.42 \mathrm{~eV}$. The wavelength of light emitted from the LED is :
Options:
A) 1243 nm
B) 875 nm
C) 650 nm
D) 1400 nm
35
Easy
The output $\mathrm{Y}$ of following circuit for given inputs is :
Options:
A) A \cdot B
B) \bar{A} \cdot B
C) \Lambda \cdot B(\Lambda+B)
D) 0
36
Easy
The acceptor level of a p-type semiconductor is $6 \mathrm{~eV}. The maximum wavelength of light which can create a hole would be : Given \mathrm{hc}=1242 \mathrm{~eV} \mathrm{~nm}$.
Options:
A) 407 nm
B) 103.5 nm
C) 414 nm
D) 207 nm
37
Easy
The correct truth table for the following logic circuit is :
Options:
A)
B)
C)
D)
38
Easy
The output (Y) of logic circuit given below is 0 only when :
Options:
A) \mathrm{A}=0, \mathrm{~B}=0
B) \mathrm{A}=0, \mathrm{~B}=1
C) \mathrm{A}=1, \mathrm{~B}=0
D) \mathrm{A=1, B=1}
39
Easy
Following gates section is connected in a complete suitable circuit. For which of the following combination, bulb will glow (ON) :
Options:
A) \mathrm{A}=1, \mathrm{~B}=1, \mathrm{C}=1, \mathrm{D}=0
B) \mathrm{A}=1, \mathrm{~B}=0, \mathrm{C}=0, \mathrm{D}=0
C) \mathrm{A}=0, \mathrm{~B}=0, \mathrm{C}=0, \mathrm{D}=1
D) \mathrm{A}=0, \mathrm{~B}=1, \mathrm{C}=1, \mathrm{D}=1
40
Easy
Which of the diode circuit shows correct biasing used for the measurement of dynamic resistance of p-n junction diode :
Options:
A)
B)
C)
D)
41
Easy
Identify the logic gate given in the circuit :
Options:
A) OR gate
B) NAND gate
C) NOR gate
D) AND gate
42
Easy
The value of net resistance of the network as shown in the given figure is :
Options:
A) (30 / 11) \Omega
B) 6 \Omega
C) (5 / 2) \Omega
D) (15 / 4) \Omega
43
Medium
To measure the temperature coefficient of resistivity \alpha of a semiconductor, an electrical arrangement shown in the figure is prepared. The arm BC is made up of the semiconductor. The experiment is being conducted at 25^{\circ} \mathrm{C} and resistance of the semiconductor arm is 3 \mathrm{~m} \Omega. Arm \mathrm{BC} is cooled at a constant rate of 2^{\circ} \mathrm{C} / \mathrm{s}. If the galvanometer \mathrm{G} shows no deflection after 10 \mathrm{~s}, then \alpha is :
Options:
A) -1 \times 10^{-2}{ }^{\circ} \mathrm{C}^{-1}
B) -2 \times 10^{-2}{ }^{\circ} \mathrm{C}^{-1}
C) -2.5 \times 10^{-2}{ }^{\circ} \mathrm{C}^{-1}
D) -1.5 \times 10^{-2}{ }^{\circ} \mathrm{C}^{-1}
44
Medium
In the given circuit if the power rating of Zener diode is 10 \mathrm{~mW}, the value of series resistance R_s to regulate the input unregulated supply is :
Options:
A) 10 \mathrm{k} \Omega
B) 10 \Omega
C) 1 \mathrm{k} \Omega
D) \frac{3}{7} \mathrm{k} \Omega<\mathrm{R}_{\mathrm{s}}<\frac{3}{5} \mathrm{k} \Omega
45
Easy
The output of the given circuit diagram is -
Options:
A)
B)
C)
D)
46
Easy
Identify the logic operation performed by the given circuit.
Options:
A) AND
B) NOR
C) OR
D) NAND
47
Easy
In the given circuit, the voltage across load resistance (R$_L$) is :
Options:
A) 8.75 V
B) 9.00 V
C) 8.50 V
D) 14.00 V
48
Easy
A Zener diode of breakdown voltage $10 \mathrm{~V}$ is used as a voltage regulator as shown in the figure. The current through the Zener diode is :
Options:
A) 0
B) 30 mA
C) 20 mA
D) 50 mA
49
Easy
The truth table for this given circuit is :
Options:
A)
B)
C)
D)
50
Easy
In the given circuit, the breakdown voltage of the Zener diode is $3.0 \mathrm{~V}. What is the value of \mathrm{I}_{\mathrm{z}}$ ?
Options:
A) 3.3 mA
B) 10 mA
C) 5.5 mA
D) 7 mA
51
Easy
The truth table of the given circuit diagram is :
Options:
A)
B)
C)
D)
52
Easy
Which of the following circuits is reverse - biased?
Options:
A)
B)
C)
D)
53
Medium
In the given circuit, the current (I) through the battery will be
Options:
A) 1A
B) 2.5 \mathrm{~A}
C) 2 \mathrm{~A}
D) 1.5 \mathrm{~A}
54
Easy
The output from NAND gate having inputs A and B given below will be,
Options:
A)
B)
C)
D)
55
Easy
For the following circuit and given inputs A and B, choose the correct option for output '$Y$'
Options:
A)
B)
C)
D)
56
Easy
In an n-p-n common emitter (CE) transistor the collector current changes from 5 $\mathrm{mA} to 16 \mathrm{~mA} for the change in base current from 100~ \mu \mathrm{A} and 200 ~\mu \mathrm{A}$, respectively. The current gain of transistor is __________.
Options:
A) 210
B) 0.9
C) 9
D) 110
57
Easy
The logic operations performed by the given digital circuit is equivalent to:
Options:
A) NOR
B) AND
C) NAND
D) OR
58
Easy
The logic performed by the circuit shown in figure is equivalent to :
Options:
A) NAND
B) AND
C) OR
D) NOR
59
Easy
If each diode has a forward bias resistance of $25 ~\Omega$ in the below circuit, Which of the following options is correct :
Options:
A) \frac{I_{3}}{I_{4}}=1
B) \frac{\mathrm{I}_{1}}{\mathrm{I}_{2}}=2
C) \frac{I_{2}}{\mathrm{I}_{3}}=1
D) \frac{I_{1}}{I_{2}}=1
60
Medium
A zener diode of power rating 1.6 W is to be used as voltage regulator. If the zener diode has a breakdown of 8V and it has to regulate voltage fluctuating between 3 V and 10 V. The value of resistance Rs for safe operation of diode will be
Options:
A) 13 $\Omega
B) 13.3 $\Omega
C) 10 $\Omega
D) 12 $\Omega
61
Easy
For a given transistor amplifier circuit in $\mathrm{CE} configuration \mathrm{V}_{\mathrm{CC}}=1 \mathrm{~V}, \mathrm{R}_{\mathrm{C}}=1 ~\mathrm{k} \Omega, \mathrm{R}_{\mathrm{b}}=100 ~\mathrm{k} \Omega and \beta=100. Value of base current \mathrm{I}_{\mathrm{b}}$ is
Options:
A) \mathrm{I}_{\mathrm{b}}=100 ~\mu \mathrm{A}
B) \mathrm{I}_{\mathrm{b}}=0.1 ~\mu \mathrm{A}
C) \mathrm{I}_{\mathrm{b}}=1.0 ~\mu \mathrm{A}
D) \mathrm{I}_{\mathrm{b}}=10 ~\mu \mathrm{A}
62
Easy
For the logic circuit shown, the output waveform at $\mathrm{Y}$ is:
Options:
A)
B)
C)
D)
63
Medium
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: Diffusion current in a p-n junction is greater than the drift current in magnitude if the junction is forward biased. Reason R: Diffusion current in a p-n junction is from the $\mathrm{n}$-side to the p-side if the junction is forward biased. In the light of the above statements, choose the most appropriate answer from the options given below
Options:
A) Both A and R are correct but R is NOT the correct explanation of A
B) A is correct but R is not correct
C) A is not correct but R is correct
D) Both A and R are correct and R is the correct explanation of A
64
Easy
Name the logic gate equivalent to the diagram attached
Options:
A) NOR
B) NAND
C) AND
D) OR
65
Easy
The resistivity $(\rho)$ of semiconductor varies with temperature. Which of the following curve represents the correct behaviour :
Options:
A)
B)
C)
D)
66
Easy
Choose the correct statement about Zener diode :
Options:
A) It works as a voltage regulator in reverse bias and behaves like simple pn junction diode in forward bias.
B) It works as a voltage regulator in both forward and reverse bias.
C) It works as a voltage regulator only in forward bias.
D) It works as a voltage regulator in forward bias and behaves like simple pn junction diode in reverse bias.
67
Easy
Match List I with List II: List I List II A. Intrinsic semiconductor I. Fermi-level near the valence bond B. n-type semiconductor II. Fermi-level in the middle of valence and conduction band. C. p-type semiconductor III. Fermi-level near the conduction band D. Metals IV. Fermi-level inside the conduction band Choose the correct answer from the options given below :
Options:
A) A-III, B-I, C-II, D-IV
B) A-II, B-I, C-III, D-IV
C) A-I, B-II, C-III, D-IV
D) A-II, B-III, C-I, D-IV
68
Easy
Given below are two statements : Statement I: In a typical transistor, all three regions emitter, base and collector have same doping level. Statement II: In a transistor, collector is the thickest and base is the thinnest segment. In the light of the above statements, choose the most appropriate answer from the options given below.
Options:
A) Statement I is correct but Statement II is incorrect
B) Both Statement I and Statement II are incorrect
C) Statement I is incorrect but Statement II is correct
D) Both Statement I and Statement II are correct
69
Easy
The effect of increase in temperature on the number of electrons in conduction band ($\mathrm{n_e}$) and resistance of a semiconductor will be as:
Options:
A) \mathrm{n}_{\mathrm{e}}$ decreases, resistance increases
B) Both $\mathrm{n}_{\mathrm{e}}$ and resistance increase
C) \mathrm{n}_{\mathrm{e}}$ increases, resistance decreases
D) Both $\mathrm{n}_{\mathrm{e}}$ and resistance decrease
70
Medium
The output Y for the inputs A and B of circuit is given by Truth table of the shown circuit is:
Options:
A)
B)
C)
D)
71
Easy
The output waveform of the given logical circuit for the following inputs A and B as shown below, is :
Options:
A)
B)
C)
D)
72
Easy
For the given logic gates combination, the correct truth table will be
Options:
A)
B)
C)
D)
73
Easy
Which one of the following statement is not correct in the case of light emitting diodes? A. It is a heavily doped p-n junction. B. It emits light only when it is forward biased. C. It emits light only when it is reverse biased. D. The energy of the light emitted is equal to or slightly less than the energy gap of the semiconductor used. Choose the correct answer from the options given below:
Options:
A) A
B) B
C) C and D
D) C
74
Easy
Statement I : When a Si sample is doped with Boron, it becomes P type and when doped by Arsenic it becomes N-type semi conductor such that P-type has excess holes and N-type has excess electrons. Statement II : When such P-type and N-type semi-conductors, are fused to make a junction, a current will automatically flow which can be detected with an externally connected ameter. In the light of above statements, choose the most appropriate answer from the options given below
Options:
A) Statement I is incorrect but statement II is correct
B) Both Statement I and statement II are correct
C) Statement I is correct but statement II is incorrect
D) Both Statement I and Statement II are incorrect
75
Medium
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R Assertion A : Photodiodes are used in forward bias usually for measuring the light intensity. Reason R : For a p-n junction diode, at applied voltage V the current in the forward bias is more than the current in the reverse bias for $\mathrm{|{V_z}| > \pm v \ge |{v_0}|} where \mathrm{v_0} is the threshold voltage and \mathrm{V_z}$ is the breakdown voltage. In the light of the above statements, choose the correct answer from the options given below
Options:
A) Both A and R are true but R is NOT the correct explanation of A
B) A is true but R is false
C) Both A and R are true and R is the correct explanation of A
D) A is false but R is true
76
Easy
The logic gate equivalent to the given circuit diagram is :
Options:
A) NOR
B) OR
C) NAND
D) AND
77
Medium
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R Assertion A : Photodiodes are preferably operated in reverse bias condition for light intensity measurement. Reason R : The current in the forward bias is more than the current in the reverse bias for a $p-n$ junction diode. In the light of the above statements, choose the correct answer from the options given below :
Options:
A) Both A and R are true and R is the correct explanation of A
B) A is false but R is true
C) A is true but R is false
D) Both A and R are true but R is NOT the correct explanation of A
78
Medium
An n.p.n transistor with current gain $\beta=100$ in common emitter configuration is shown in figure. The output voltage of the amplifier will be
Options:
A) 0.1 V
B) 1.0 V
C) 10 V
D) 100 V
79
Easy
Identify the solar cell characteristics from the following options :
Options:
A)
B)
C)
D)
80
Easy
For a constant collector-emitter voltage of $8 \mathrm{~V}, the collector current of a transistor reached to the value of 6 \mathrm{~mA} from 4 \mathrm{~mA}, whereas base current changed from 20 \,\mu \mathrm{A} to 25 \,\mu \mathrm{A}$ value. If transistor is in active state, small signal current gain (current amplification factor) will be :
Options:
A) 240
B) 400
C) 0.0025
D) 200
81
Easy
A logic gate circuit has two inputs A and B and output Y. The voltage waveforms of A, B and Y are shown below. The logic gate circuit is :
Options:
A) AND gate
B) OR gate
C) NOR gate
D) NAND gate
82
Easy
In the circuit, the logical value of $A=1 or B=1 when potential at A or B is 5 \mathrm{~V} and the logical value of A=0 or B=0 when potential at A or B is 0 \mathrm{~V}$. The truth table of the given circuit will be :
Options:
A) \matrix{
A & B & Y \cr
0 & 0 & 0 \cr
1 & 0 & 0 \cr
0 & 1 & 0 \cr
1 & 1 & 1 \cr
}
B) \matrix{
A & B & Y \cr
0 & 0 & 0 \cr
1 & 0 & 1 \cr
0 & 1 & 1 \cr
1 & 1 & 1 \cr
}
C) \matrix{
A & B & Y \cr
0 & 0 & 0 \cr
1 & 0 & 0 \cr
0 & 1 & 0 \cr
1 & 1 & 0 \cr
}
D) \matrix{
A & B & Y \cr
0 & 0 & 1 \cr
1 & 0 & 1 \cr
0 & 1 & 1 \cr
1 & 1 & 0 \cr
}
83
Medium
In the given circuit the input voltage Vin is shown in figure. The cut-in voltage of p-n junction diode (D1 or D2) is 0.6 V. Which of the following output voltage (V0) waveform across the diode is correct?
Options:
A)
B)
C)
D)
84
Easy
In the following circuit, the correct relation between output (Y) and inputs A and B will be :
Options:
A) Y = AB
B) Y = A + B
C) Y = \overline {AB}
D) Y = \overline {A+B}
85
Easy
For using a multimeter to identify diode from electrical components, choose the correct statement out of the following about the diode :
Options:
A) It is two terminal device which conducts current in both directions.
B) It is two terminal device which conducts current in one direction only.
C) It does not conduct current gives an initial deflection which decays to zero.
D) It is three terminal device which conducts current in one direction only between central terminal and either of the remaining two terminals
86
Easy
Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R. Assertion A : n-p-n transistor permits more current than a p-n-p transistor. Reason R : Electrons have greater mobility as a charge carrier. Choose the correct answer from the options given below :
Options:
A) Both A and R are true, and R is correct explanation of A.
B) Both A and R are true but R is NOT the correct explanation of A.
C) A is true but R is false.
D) A is false but R is true.
87
Easy
For a transistor to act as a switch, it must be operated in
Options:
A) Active region.
B) Saturation state only.
C) Cut-off state only.
D) Saturation and cut-off state.
88
Easy
Identify the correct Logic Gate for the following output (Y) of two inputs A and B.
Options:
A)
B)
C)
D)
89
Easy
The positive feedback is required by an amplifier to act an oscillator. The feedback here means :
Options:
A) External input is necessary to sustain ac signal in output.
B) A portion of the output power is returned back to the input.
C) Feedback can be achieved by LR network.
D) The base-collector junction must be forward biased.
90
Medium
The I-V characteristics of a p-n junction diode in forward bias is shown in the figure. The ratio of dynamic resistance, corresponding to forward bias voltage of 2 V and 4 V respectively, is :
Options:
A) 1 : 2
B) 5 : 1
C) 1 : 40
D) 20 : 1
91
Easy
Identify the logic operation performed by the given circuit:
Options:
A) AND gate
B) OR gate
C) NOR gate
D) NAND gate
92
Medium
The photodiode is used to detect the optical signals. These diodes are preferably operated in reverse biased mode because :
Options:
A) fractional change in majority carriers produce higher forward bias current
B) fractional change in majority carriers produce higher reverse bias current
C) fractional change in minority carriers produce higher forward bias current
D) fractional change in minority carriers produce higher reverse bias current
93
Medium
In the given figure, each diode has a forward bias resistance of 30$\Omega$ and infinite resistance in reverse bias. The current I1 will be :
Options:
A) 3.75 A
B) 2.35 A
C) 2 A
D) 2.73 A
94
Medium
If VA and VB are the input voltages (either 5V or 0V) and V0 is the output voltage then the two gates represented in the following circuit (A) and (B) are :-
Options:
A) AND and OR Gate
B) OR and NOT Gate
C) NAND and NOR Gate
D) AND and NOT Gate
95
Easy
Statement - I :To get a steady dc output from the pulsating voltage received from a full wave rectifier we can connect a capacitor across the output parallel to the load RL.Statement - II :To get a steady dc output from the pulsating voltage received from a full wave rectifier we can connect an inductor in series with RL.In the light of the above statements, choose the most appropriate answer from the options given below :
Options:
A) Statement I is true but Statement II is false
B) Statement I is false but Statement II is true
C) Both Statement I and Statement II are false
D) Both Statement I and Statement II are true
96
Easy
In the following logic circuit the sequence of the inputs A, B are (0, 0), (0, 1), (1, 0) and (1, 1). The output Y for this sequence will be :
Options:
A) 1, 0, 1, 0
B) 0, 1, 0, 1
C) 1, 1, 1, 0
D) 0, 0, 1, 1
97
Easy
Choose the correct waveform that can represent the voltage across R of the following circuit, assuming the diode is ideal one :
Options:
A)
B)
C)
D)
98
Easy
For a transistor $\alpha and \beta are given as \alpha = {{{I_C}} \over {{I_E}}} and \beta = {{{I_C}} \over {{I_B}}}. Then the correct relation between \alpha and \beta$ will be :
Options:
A) \alpha = {{1 - \beta } \over \beta }
B) \beta = {\alpha \over {1 - \alpha }}
C) \alpha \beta = 1
D) \alpha = {\beta \over {1 - \beta }}
99
Easy
For a transistor in CE mode to be used as an amplifier, it must be operated in :
Options:
A) Both cut-off and Saturation
B) Saturation region only
C) Cut-off region only
D) The active region only
100
Easy
Four NOR gates are connected as shown in figure. The truth table for the given figure is :
Options:
A)
B)
C)
D)
101
Easy
Identify the logic operation carried out by the given circuit :-
Options:
A) OR
B) AND
C) NOR
D) NAND
102
Easy
Statement I : By doping silicon semiconductor with pentavalent material, the electrons density increases.Statement II : The n-type semiconductor has net negative charge.In the light of the above statements, choose the most appropriate answer from the options given below :
Options:
A) Statement - I is true but Statement - II is false.
B) Statement - I is false but Statement - II is true.
C) Both Statement I and Statement II are true.
D) Both Statement I and Statement II are false.
103
Easy
Find the truth table for the function Y of A and B represented in the following figure.
Options:
A)
B)
C)
D)
104
Easy
Identify the logic operation carried out.
Options:
A) OR
B) AND
C) NOR
D) NAND
105
Medium
Consider a situation in which reserve biased current of a particular P-N junction increases when it is exposed to a light of wavelength $\le$ 621 nm. During this process, enhancement in carrier concentration takes place due to generation of hole-electron pairs. The value of band gap is nearly.
Options:
A) 1 eV
B) 4 eV
C) 0.5 eV
D) 2 eV
106
Easy
For the circuit shown below, calculate the value of Iz :
Options:
A) 25 mA
B) 0.1 A
C) 0.15 A
D) 0.05 A
107
Easy
The correct relation between $\alpha (ratio of collector current to emitter current) and \beta$ (ratio of collector current to base current) of a transistor is :
Options:
A) \beta = {\alpha \over {1 + \alpha }}
B) \alpha = {\beta \over {1 - \alpha }}
C) \alpha = {\beta \over {1 + \beta }}
D) \beta = {1 \over {1 - \alpha }}
108
Easy
Which one of the following will be the output of the given circuit?
Options:
A) XOR Gate
B) NOR Gate
C) NAND Gate
D) AND Gate
109
Easy
The output of the given combination gates represents :
Options:
A) AND Gate
B) NOR Gate
C) NAND Gate
D) XOR Gate
110
Easy
The following logic gate is equivalent to :
Options:
A) NOR Gate
B) NAND Gate
C) OR Gate
D) AND Gate
111
Easy
Draw the output signal Y in the given combination of gates.
Options:
A)
B)
C)
D)
112
Easy
LED is constructed from Ga-As-P semiconducting material. The energy gap of this LED is 1.9 eV. Calculate the wavelength of light emitted and its colour.[h = 6.63 $\times 10-34 Js and c = 3 \times 108 ms-$1]
Options:
A) 654 nm and orange colour
B) 654 nm and red colour
C) 1046 nm and red colour
D) 1046 nm and blue colour
113
Easy
For extrinsic semiconductors; when doping level is increased;
Options:
A) Fermi-level of both p-type and n-type semiconductors will go upward for T > TFK and downward for T < TFK, where TF is Fermi temperature.
B) Fermi-level of p-type semiconductor will go upward and Fermi-level of n-type semiconductors will go downward
C) Fermi-level of p and n-type semiconductors will not be affected.
D) Fermi-level of p-type semiconductors will go downward and Fermi-level of n-type semiconductor will go upward.
114
Easy
The truth table for the following logic circuit is :
Options:
A)
B)
C)
D)
115
Easy
A 5V battery is connected across the points X and Y. Assume D1 and D2 to be normal silicon diodes. Find the current supplied by the battery if the +ve terminal of the battery is connected to point X.
Options:
A) \sim $ 0.5 A
B) \sim $ 1.5 A
C) \sim $ 0.43 A
D) \sim $ 0.86 A
116
Easy
The logic circuit shown above is equivalent to :
Options:
A)
B)
C)
D)
117
Medium
Given below are two statements :Statement I : PN junction diodes can be used to function as transistor, simply by connecting two diodes, back to back, which acts as the base terminal.Statement II : In the study of transistor, the amplification factor $\beta$ indicates ratio of the collector current to the base current.In the light of the above statements, choose the correct answer from the options given below.
Options:
A) Both Statement I and Statement II are false
B) Statement I is false but Statement II is true
C) Both Statement I and Statement II are true
D) Statement I is true but Statement II is false
118
Easy
Zener breakdown occurs in a p $-$ n junction having p and n both :
Options:
A) heavily doped and have wide depletion layer.
B) lightly doped and have narrow depletion layer.
C) heavily doped and have narrow depletion layer.
D) lightly doped and have wide depletion layer.
119
Easy
If an emitter current is changed by 4 mA, the collector current changes by 3.5 mA. The value of $\beta$ will be :
Options:
A) 0.875
B) 0.5
C) 3.5
D) 7
120
Medium
Identify the correct output signal Y in the given combination of gates (as shown) for the given inputs A and B.
Options:
A)
B)
C)
D)
121
Medium
Two Zener diodes (A and B) having breakdown voltages of 6 V and 4 V respectively, are connected as shown in the circuit below. The output voltage V0 variation with input voltage linearly increasing with time, is given by : (Vinput = 0 V at t = 0) (figures are qualitative)
Options:
A)
B)
C)
D)
122
Medium
With increasing biasing voltage of a photodiode, the photocurrent magnitude :
Options:
A) Increases initially and after attaining
certain value, it decreases
B) Increases linearly
C) Increases initially and saturates finally
D) Remains constant
123
Medium
Identify the operation performed by the circuit given below :
Options:
A) AND
B) NAND
C) OR
D) NOT
124
Medium
Take the breakdown voltage of the zener diode used in the given circuit as 6V. For the input voltage shown in figure below, the time variation of the output voltage is: (Graphs drawn are schematic and not to scale)
Options:
A)
B)
C)
D)
125
Medium
If a semiconductor photodiode can detect a photon with a maximum wavelength of 400 nm, then its band gap energy is : Planck’s constant h = 6.63 $ \times 10–34 J.s. Speed of light c = 3 \times $ 108 m/s
Options:
A) 1.5 eV
B) 2.0 eV
C) 3.1 eV
D) 1.1 eV
126
Medium
Which of the following will NOT be observed when a multimeter (operating in resistance measuring mode) probes connected across a component, are just reversed?
Options:
A) Multimeter shows NO deflection in both cases i.e. before and after reversing the probes if the
chosen component is metal wire.
B) Multimeter shows a deflection, accompanied by a splash of light out of connected component in one direction and NO deflection on reversing the probes if the chosen component is LED.
C) Multimeter shows an equal deflection in both cases i.e. before and after reversing the probes if
the chosen component is resistor.
D) Multimeter shows NO deflection in both cases i.e. before and after reversing the probes if the
chosen component is capacitor.
127
Medium
When a diode is forward biased, it has a voltage drop of 0.5 V. The safe limit of current through the diode is 10 mA. If a battery of emf 1.5 V is used in the circuit, the value of minimum resistance to be connected in series with the diode so that the current does not exceed the safe limit is
Options:
A) 50 $\Omega
B) 200 $\Omega
C) 300 $\Omega
D) 100 $\Omega
128
Medium
In the following digital circuit, what will be the output at ‘Z’, when the input (A, B) are (1, 0), (0, 0), (1, 1,), (0, 1)
Options:
A) 1, 1, 0, 1
B) 0, 1, 0, 0
C) 1, 0, 1, 1
D) 0, 0, 1, 0
129
Medium
The current i in the network is :
Options:
A) 0.6 A
B) 0.3 A
C) 0 A
D) 0.2 A
130
Medium
Two identical capacitors A and B, charged to the same potential 5V are connected in two different circuits as shown below at time t = 0. If the charge on capacitors A and B at time t = CR is QA and QB respectively, then (Here e is the base of natural logarithm)
Options:
A) QA = ${{CV} \over e}, QB = {{VC} \over 2}
B) QA = ${{CV} \over 2}, QB = {{VC} \over e}
C) QA = VC, QB = ${{VC} \over e}
D) QA = VC, QB = CV
131
Medium
In the given circuit, value of Y is :
Options:
A) toggles between 0 and 1
B) 1
C) will not execute
D) 0
132
Medium
Boolean relation at the output stage-Y for the following circuit is :
Options:
A) A.B
B) \overline A + \overline B
C) \overline A .\overline B
D) A + B
133
Medium
In the figure, potential difference between A and B is :
Options:
A) 10 V
B) 5 V
C) zero
D) 15 V
134
Medium
Which of the following gives a reversible operation?
Options:
A)
B)
C)
D)
135
Medium
Figure shows a DC voltage regulator circuit, with a Zener diode of breakdown voltage = 6V. If the unregulated input voltage varies between 10 V to 16 V, then what is maximum Zener current?
Options:
A) 3.5 mA
B) 1.5 mA
C) 2.5 mA
D) 7.5 mA
136
Medium
The transfer characteristic curve of a transistor, having input and output resistance 100 $\Omega and 100 k\Omega $ respectively is shown in the figure. The voltage and power gain, are respectively:
Options:
A) 5 × 104, 5 × 105
B) 5 × 104, 5 × 106
C) 5 × 104, 2.5 × 106
D) 2.5 × 104, 2.5 × 106
137
Medium
The truth table for the circuit given in the fig. is:
Options:
A) \left| {\matrix{
A & B & Y \cr
0 & 0 & 1 \cr
0 & 1 & 1 \cr
1 & 0 & 1 \cr
1 & 1 & 1 \cr
} } \right|
B) \left| {\matrix{
A & B & Y \cr
0 & 0 & 1 \cr
0 & 1 & 0 \cr
1 & 0 & 0 \cr
1 & 1 & 0 \cr
} } \right|
C) \left| {\matrix{
A & B & Y \cr
0 & 0 & 1 \cr
0 & 1 & 1 \cr
1 & 0 & 0 \cr
1 & 1 & 0 \cr
} } \right|
D) \left| {\matrix{
A & B & Y \cr
0 & 0 & 0 \cr
0 & 1 & 0 \cr
1 & 0 & 1 \cr
1 & 1 & 1 \cr
} } \right|
138
Medium
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, RL = 4k$\Omega . The series resistance of the circuit is Ri = 1 k\Omega $. If the battery voltage VB varies from 8 V to 16 V, what are the minimum and maximum values of the current through Zener diode?
Options:
A) 0.5 mA; 8.5 mA
B) 1.5 mA; 8.5 mA
C) 1 mA; 8.5 mA
D) 0.5 mA; 6 mA
139
Medium
An n-p-n transistor operates as a common emitter amplifier, with a power gain of 60 dB. The input circuit resistance is 100$\Omega and the output load resistance is 10 k\Omega . The common emitter current gain \beta $ is :
Options:
A) 104
B) 102
C) 6 × 102
D) 60
140
Medium
The logic gate equivalent to the given logic circuit is :-
Options:
A) NAND
B) AND
C) NOR
D) OR
141
Medium
An NPN transistor is used in common emitter configuration as an amplifier with 1 k$\Omega $ load resistance. Signal voltage of 10 mV is applied across the base-emitter. This produces a 3 mA change in the collector current and 15μA change in the base current of the amplifier. The input resistance and voltage gain are :
Options:
A) 0.67 kW, 200
B) 0.33 kW, 1.5
C) 0.67 kW, 300
D) 0.33 kW, 300
142
Medium
A common emitter amplifier circuit, built using an npn transistor, is shown in the figure. Its dc current gain is 250, RC = 1k$\Omega$ and VCC = 10 V. What is the minimum base current for VCE to reach saturation ?
Options:
A) 100 $\mu $A
B) 7 $\mu $A
C) 10 $\mu $A
D) 40 $\mu $A
143
Medium
The reverse breakdown voltage of a Zener diode is 5.6 V in the given circuit. The current IZ through the Zener is :
Options:
A) 7 mA
B) 17 mA
C) 15mA
D) 10 mA
144
Medium
In the figure, given that VBB supply can vary from 0 to 5.0 V, VCC = 5V, $\beta dc = 200, RB = 100 k\Omega , RC = 1 k\Omega $ and VBE = 1.0 V. The minimum base current and the input voltage at which the transistor will go to saturation, will be respectively :
Options:
A) 20 $\mu $A and 2.8 V
B) 25 $\mu $A and 2.8 V
C) 20 $\mu $A and 3.5 V
D) 25 $\mu $A and 3.5 V
145
Medium
The output of the given logic circuit is :
Options:
A) \overline A B
B) AB + \overline {AB}
C) A\overline B + \overline A B
D) A\overline B
146
Medium
The circuit shown below contains two ideal diodes, each with a forward resistance of 50 $\Omega . If the battery voltage is 6 V, the current through the 100 \Omega $ resistance (in Amperes) is :
Options:
A) 0.027
B) 0.030
C) 0.036
D) 0.020
147
Medium
In the given circuit the current through Zener Diode is close to:
Options:
A) 0.0 mA
B) 6.7 mA
C) 4.0 mA
D) 6.0 mA
148
Medium
For the circuit shown below, the current through the Zener diode is -
Options:
A) 5 mA
B) zero
C) 14 mA
D) 9 mA
149
Medium
To get output 1 at R, for the given logic gate circuit the input values must be
Options:
A) x = 0, y = 0
B) x = 1, y = 0
C) x = 0, y = 1
D) x = 1, y = 1
150
Medium
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 V0 changes by : (assume that the Ge diode has large breakdown voltage)
Options:
A) 0.8 V
B) 0.6 V
C) 0.2 V
D) 0.4 V
151
Medium
Mobility of electrons in a semiconductor is defined as the ratio of their drift velocity to the applied electric field. If, for an n-type semiconductor, the density of electrons is 1019 m$-$3 and their mobility is 1.6 m2/(V.s) then the resistivity of the semiconductor (since it is an n-type semiconductor contribution of holes is ignored) is close to :
Options:
A) 2\,\Omega $m
B) 4$\,\Omega $m
C) 0.4 $\,\Omega $m
D) 0.2 $\,\Omega $m
152
Medium
In the given circuit, the current through zener diode is :
Options:
A) 5.5 mA
B) 6.7 mA
C) 2.5 mA
D) 3.3 mA
153
Medium
The reading of the ammeter for a silicon diode in the given circuit is :
Options:
A) 13.5 mA
B) 0
C) 15 mA
D) 11.5 mA
154
Medium
Truth table for the following digital circuit will be :
Options:
A)
B)
C)
D)
155
Medium
In a common emitter configuration with suitable bias, it is given that ${R_L} is the load resistance and {R_{BE}} is small signal dynamic resistance (input side). Then, voltage gain, current gain and power gain are given, respectively, by : \beta is curret gain, {{\rm I}_B},{{\rm I}_C} and {{\rm I}_E}$ are respectively base, collector and emitter currents.
Options:
A) \beta {{{R_L}} \over {{R_{BE}}}},{{\Delta {{\rm I}_C}} \over {\Delta {{\rm I}_B}}},{\beta ^2}{{{R_L}} \over {{R_{BE}}}}
B) \beta {{{R_L}} \over {{R_{BE}}}},{{\Delta {{\rm I}_E}} \over {\Delta {{\rm I}_B}}},{\beta ^2}{{{R_L}} \over {{R_{BE}}}}
C) {\beta ^2}{{{R_L}} \over {{R_{BE}}}},{{\Delta {{\rm I}_C}} \over {\Delta {{\rm I}_E}}},{\beta ^2}{{{R_L}} \over {{R_{BE}}}}
D) {\beta ^2}{{{R_L}} \over {{R_{BE}}}},{{\Delta {{\rm I}_C}} \over {\Delta {{\rm I}_B}}},\beta {{{R_L}} \over {{R_{BE}}}}
156
Medium
The current gain of a common emitter amplifier is 69. If the emitter current is 7.0 mA, collector current is :
Options:
A) 9.6 mA
B) 6.9 mA
C) 0.69 mA
D) 69 mA
157
Medium
The V-I characteristic of a diode is shown in the figure. The ratio of forward to reverse bias resistance is :
Options:
A) 10
B) 10$-$6
C) 106
D) 100
158
Medium
What is the conductivity of a semiconductor sale having electron concentration of $5 \times {10^{18}}\,\,{m^{ - 3}}, hole concentration of 5 \times {10^{19}}\,\,{m^{ - 3}}, electron mobility of 2.0 m2 V-1 s-1 and hole mobility of 0.01 m2 V-1 s-1 ? (Take charge of electronas 1.6 \times 10 -$19 c)
Options:
A) 1.68 ($\Omega -m)-$1
B) 1.83 ($\Omega -m)-$1
C) 0.59 ($\Omega -m)-$1
D) 1.20 ($\Omega -m)-$1
159
Medium
In a common emitter amplifier circuit using an n-p-n transistor, the phase difference between the input and the output voltages will be:
Options:
A) 180°
B) 45°
C) 90°
D) 135°
160
Medium
To get an output of 1 from the circuit shown in figure the input must be :
Options:
A) a = 0, b = 1, c = 0
B) a = 1, b = 0, c = 0
C) a = 1, b = 0, c = 1
D) a = 0, b = 0, c = 1
161
Medium
The ratio (R) of output resistance r0, and the input resistance ri in measurements of input and output characteristics of a transistor is typically in the range:
Options:
A) R ~ 102 $-$ 103
B) R ~ 1 $-$ 10
C) R ~ 0.1 $-$ 0.01
D) R ~ 0.1 $-$ 1.0
162
Medium
A realistic graph depicting the variation of the reciprocal of input resistance in an input characteristics measurement in a commonemitter transistor configuration is :
Options:
A)
B)
C)
D)
163
Medium
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 :
Options:
A) 0 $-$ 5 V
B) 0 $-$ 8 V
C) 0 $-$ 12 V
D) 0 $-$ 24 V
164
Medium
An unknown transistor needs to be identified as a npn or pnp type. A 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 pnp transistor ?
Options:
A) + ve termial 1, $-$ve terminal 2, resistance high
B) + ve termial 2, $-$ve terminal 1, resistance high
C) + ve termial 3, $-$ve terminal 2, resistance high
D) + ve termial 2, $-$ve terminal 3, resistance low
165
Medium
The truth table given in fig. represents : A B Y 0 0 0 0 1 1 1 0 1 1 1 1
Options:
A) AND - Gate
B) OR - Gate
C) NAND - Gate
D) NOR - Gate
166
Medium
The temperature dependence of resistance of $Cu and undoped Si in the temperature range 300-400 K,$ is best described by :
Options:
A) Linear increases for $Cu, exponential decrease of Si.
B) Linear decrease for $Cu, linear decrease for Si
C) Linear increase for $Cu, linear increase for Si.
D) Linear increase for $Cu, exponential increase for Si
167
Medium
If $a, b, c, d are inputs to a gate and x$ is its output, then, as per the following time graph, the gate is :
Options:
A) OR
B) NAND
C) NOT
D) AND
168
Medium
Identify the semiconductor devices whose characteristics are given below, in the order $(a), (b), (c), (d)$ :
Options:
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
169
Medium
A red $LED emits light at 0.1 watt uniformly around it. The amplitude of the electric field of the light at a distance of 1 m$ from the diode is :
Options:
A) 5.48 V/m
B) 7.75 V/m
C) 1.73 V/m
D) 2.45 V/m
170
Medium
The forward biased diode connection is:
Options:
A)
B)
C)
D)
171
Medium
The current voltage relation of diode is given by ${\rm I} = \left( {{e^{100V/T}} - 1} \right)mA, where the applied voltage V is in volts and the temperature T is in degree kelvin. If a student makes an error measuring \pm 0.01\,V while measuring the current of 5 mA at 300 K, what will be the error in the value of current on mA$?
Options:
A) 0.2 mA
B) 0.02 mA
C) 0.5 mA
D) 0.05 mA
172
Medium
The ${\rm I}-V characteristic of an LED$ is
Options:
A)
B)
C)
D)
173
Medium
A diode detector is used to detect an amplitude modulated wave of $60\% modulation by using a condenser of capacity 250 picofarad in parallel with a load resistance 100 kilo ohm.$ Find the maximum modulated frequency which could be detected by it.
Options:
A) 10.62 MHz
B) 10.62 kHz
C) 5.31 MHz
D) 5.31 kHz
174
Medium
Truth table for system of four $NAND$ gates as shown in figure is:
Options:
A)
B)
C)
D)
175
Medium
The combination of gates shown below yields
Options:
A) OR gate
B) NOT gate
C) XOR gate
D) NAND gate
176
Medium
The logic circuit shown below has the input waveforms $'A' and 'B'$ as shown. Pick out the correct output waveform. Output is
Options:
A)
B)
C)
D)
177
Medium
A $p-n junction (D) shown in the figure can act as a rectifier. An alternating current source (V) is connected in the circuit. The current (I) in the resistor (R)$ can be shown by :
Options:
A)
B)
C)
D)
178
Medium
In the circuit below, $A and B represent two inputs and C$ represents the output. The circuit represents
Options:
A) NOR gate
B) AND gate
C) NAND gate
D) OR gate
179
Medium
A working transistor with its three legs marked $P,Q and R is tested using a multi-meter. No conduction is found between P and Q. By connecting the common (negative) terminal of the multi-meter to R and the other (positive) terminal to P or Q,$ some resistance is seen on the multi-meter. Which of the following is true for the transistor?
Options:
A) It is an $npn transistor with R$ as base
B) It is an $pnp transistor with R$ as collector
C) It is an $pnp transistor with R$ as emitter
D) It is an $npn transistor with R$ as collector
180
Medium
If in a $p-n junction diode, a square input signal of 10 V is applied as shown Then the output signal across {R_L}$ will be
Options:
A)
B)
C)
D)
181
Medium
Carbon, silicon and germanium have four valence electrons each. At room temperature which one of the following statements is most appropriate ?
Options:
A) The number of free electrons for conduction is significant only in $Si and Ge but small in C.
B) The number of free conduction electrons is significant in $C but small in Si and Ge.
C) The number of free conduction electrons is negligibly small in all the three.
D) The number of free electrons for conduction is significant in all the three
182
Medium
If the lattice constant of this semiconductor is decreased, then which of the following is correct?
Options:
A) All ${E_c},{E_g},{E_v}$ increase
B) {E_c} and {E_v} increase, but {E_g}$ decreases
C) {E_c} and {E_v} decrease, but {E_g}$ increases
D) All ${E_c},{E_g},{E_v}$ decrease
183
Medium
In the following, which one of the diodes is reverse biased?
Options:
A)
B)
C)
D)
184
Medium
The circuit has two oppositively connected ideal diodes in parallel. What is the current following in the circuit?
Options:
A) 1.71 A
B) 2.00 A
C) 2.31 A
D) 1.33 A
185
Medium
In a common base mode of a transistor, the collector current is $5.488 mA for an emitter current of 5.60mA. The value of the base current amplification factor \left( \beta \right)$ will be
Options:
A) 49
B) 50
C) 51
D) 48
186
Medium
If the ratio of the concentration of electrons to that of holes in a semiconductor is ${7 \over 5} and the ratio of currents is {7 \over 4},$ then what is the ratio of their drift velocities?
Options:
A) {5 \over 8}
B) {4 \over 5}
C) {5 \over 4}
D) {4 \over 7}
187
Medium
A solid which is not transparent to visible light and whose conductivity increases with temperature is formed by
Options:
A) Ionic bonding
B) Covalent bonding
C) Vander Waals bonding
D) Metallic bonding
188
Medium
In a full wave rectifier circuit operating from $50 Hz$ mains frequency, the fundamental frequency in the ripple would be
Options:
A) 25 Hz
B) 50 Hz
C) 70.7 Hz
D) 100 Hz
189
Medium
In a common base amplifier, the phase difference between the input signal voltage and output voltage is
Options:
A) \pi
B) {\pi \over 4}
C) {\pi \over 2}
D) 0
190
Medium
The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than $2480 nm is incident on it. The band gap in (eV)$ for the semiconductor is
Options:
A) 2.5 eV
B) 1.1 eV
C) 0.7 eV
D) 0.5 eV
191
Medium
A piece of copper and another of germanium are cooled from room temperature to $77K,$ the resistance of
Options:
A) copper increases and germanium decreases
B) each of them decreases
C) each of them increases
D) copper decreases and germanium increases
192
Medium
The manifestation of band structure in solids is due to
Options:
A) Bohr's correspondence principle
B) Pauli's exclusion principle
C) Heisenberg's uncertainty principle
D) Boltzmann's law
193
Medium
When $p-n$ junction diode is forward biased then
Options:
A) both the depletion region and barrier height are reduced
B) the depletion region is widened and barrier height is reduced
C) the depletion region is reduced and barrier height is increased
D) both the depletion region and barrier height are increased
194
Medium
When $npn$ transistor is used as an amplifer
Options:
A) electrons move from collector to base
B) holes move from emitter to base
C) electrons move from base to collector
D) holes move from base to emitter
195
Medium
For a transistor amplifier in common emitter configuration for load impedance of $1k\,\Omega \left( {{h_{fe}} = 50} \right. and \left. {{h_{oe}} = 25} \right)$ the current gain is
Options:
A) -24.8
B) -15.7
C) -5.2
D) -48.78
196
Medium
The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the
Options:
A) crystal structure
B) variation of the number of charge carries with temperature
C) type of bonding
D) variation of scattering mechanism with temperature
197
Medium
In the middle of the depletion layer of a reverse- biased $p-n$ junction, the
Options:
A) electric field is zero
B) potential is maximum
C) electric field is maximum
D) potential is zero
198
Medium
A strip of copper and another of germanium are cooled from room temperature to $80K.$ The resistance of
Options:
A) each of these decreases
B) copper strip increases and that of germanium decreases
C) copper strip decreases and that of germanium increases
D) each of these increases
199
Medium
By increasing the temperature, the specific resistance of a conductor and a semiconductor
Options:
A) increases for both
B) decreases for both
C) increases, decreases
D) decreases, increases
200
Medium
At absolute zero, Si acts as
Options:
A) non-metal
B) metal
C) insulator
D) none of these
201
Medium
The energy band gap is maximum in
Options:
A) metals
B) superconductors
C) insulator
D) semiconductor
202
Medium
The part of a transistor which is most heavily doped to produce large number of majority carriers is
Options:
A) emmiter
B) base
C) collector
D) can be any of the above three
203
Easy
A voltage regulating circuit consisting of Zener diode, having break-down voltage of 10 V and maximum power dissipation of 0.4 W , is operated at 15 V . The approximate value of protective resistance in this circuit is \_\_\_\_ \Omega.
Options:
204
Easy
A potential divider circuit is connected with a dc source of $20 \mathrm{~V}, a light emitting diode of glow in voltage 1.8 \mathrm{~V} and a zener diode of breakdown voltage of 3.2 \mathrm{~V}. The length (PR) of the resistive wire is 20 \mathrm{~cm}. The minimum length of PQ to just glow the LED is _________ \mathrm{cm}$.
Options:
205
Medium
From the given transfer characteristic of a transistor in $\mathrm{CE} configuration, the value of power gain of this configuration is 10^{x}, for \mathrm{R}_{\mathrm{B}}=10 ~\mathrm{k} \Omega, and \mathrm{R}_{\mathrm{C}}=1 ~\mathrm{k} \Omega. The value of x$ is __________.
Options:
206
Easy
A $8 \mathrm{~V} Zener diode along with a series resistance \mathrm{R} is connected across a 20 \mathrm{~V} supply (as shown in the figure). If the maximum Zener current is 25 \mathrm{~mA}, then the minimum value of R will be _______ \Omega$.
Options:
207
Easy
If the potential barrier across a p-n junction is $0.6 \mathrm{~V}. Then the electric field intensity, in the depletion region having the width of 6 \times 10^{-6} \mathrm{~m}, will be __________ \times 10^{5} \mathrm{~N} / \mathrm{C}$.
Options:
208
Easy
The typical transfer characteristics of a transistor in CE configuration is shown in figure. A load resistor of $2 \,k \Omega is connected in the collector branch of the circuit used. The input resistance of the transistor is 0.50 \,\mathrm{k} \Omega$. The voltage gain of the transistor is ______________.
Options:
209
Easy
In the circuit shown below, maximum zener diode current will be _________ $\mathrm{mA}$.
Options:
210
Easy
Two ideal diodes are connected in the network as shown in figure. The equivalent resistance between A and B is __________ $\Omega$.
Options:
211
Easy
The energy band gap of semiconducting material to produce violet (wavelength = 4000$\mathop A\limits^o ) LED is ______________ \mathrm{eV}$. (Round off to the nearest integer).
Options:
212
Medium
The circuit diagram used to study the characteristic curve of a zener diode is connected to variable power supply (0 $- 15 V) as shown in figure. A zener diode with maximum potential Vz = 10 V and maximum power dissipation of 0.4 W is connected across a potential divider arrangement. The value of resistance RP connected in series with the zener diode to protect it from the damage is ________________ \Omega$.
Options:
213
Easy
A potential barrier of 0.4 V exists across a p-n junction. An electron enters the junction from the n-side with a speed of 6.0 $\times 105 ms-1. The speed with which electron enters the p side will be {x \over 3} \times {10^5} ms-1 the value of x is _____________. (Given mass of electron = 9 \times 10-31 kg, charge on electron = 1.6 \times 10-$19 C.)
Options:
214
Medium
A transistor is used in an amplifier circuit in common emitter mode. If the base current changes by 100 $\muA, it brings a change of 10 mA in collector current. If the load resistance is 2 k\Omega and input resistance is 1 k\Omega, the value of power gain is x \times$ 104. The value of x is _____________.
Options:
215
Medium
A zener of breakdown voltage Vz = 8 V and maximum zener current, IZM = 10 mA is subjectd to an input voltage Vi = 10 V with series resistance R = 100 $\Omega$. In the given circuit RL represents the variable load resistance. The ratio of maximum and minimum value of RL is _____________.
Options:
216
Easy
The cut-off voltage of the diodes (shown in figure) in forward bias is 0.6 V. The current through the resister of 40 $\Omega$ is __________ mA.
Options:
217
Easy
As per the given circuit, the value of current through the battery will be ____________ A.
Options:
218
Easy
In an experiment of CE configuration of n-p-n transistor, the transfer characteristics are observed as given in figure. If the input resistance is 200 $\Omega and output resistance is 60 \Omega$, the voltage gain in this experiment will be ____________.
Options:
219
Easy
In the given circuit, the value of current IL will be ____________ mA. (When RL = 1k$\Omega$)
Options:
220
Medium
A transistor is used in common-emitter mode in an amplifier circuit. When a signal of 10 mV is added to the base-emitter voltage, the base current changes by 10 $\muA and the collector current changes by 1.5 mA. The load resistance is 5 k\Omega$. The voltage gain of the transistor will be _________.
Options:
221
Easy
A zener diode of power rating 2W is to be used as a voltage regulator. If the zener diode has a breakdown of 10 V and it has to regulate voltage fluctuated between 6 V and 14 V, the value of Rs for safe operation should be ___________ $\Omega$.
Options:
222
Medium
A circuit is arranged as shown in figure. The output voltage V0 is equal to ................... V.
Options:
223
Medium
For the given circuit, the power across Zener diode is .............. mW.
Options:
224
Easy
A transistor is connected in common emitter circuit configuration, the collector supply voltage is 10 V and the voltage drop across a resistor of 1000 $\Omega in the collector circuit is 0.6 V. If the current gain factor (\beta) is 24, then the base current is _____________ \mu$A. (Round off to the Nearest Integer)
Options:
225
Easy
In a semiconductor, the number density of intrinsic charge carries at 27$^\circC is 1.5 \times 1016/m3. If the semiconductor is doped with impurity atom, the hole density increases to 4.5 \times 1022/m3. The electron density in the doped semiconductor is ___________ \times$ 109/m3.
Options:
226
Medium
In a given circuit diagram, a 5 V zener diode along with a series resistance is connected across a 50 V power supply. The minimum value of the resistance required, if the maximum zener current is 90 mA will be __________ $\Omega$.
Options:
227
Easy
A zener diode having zener voltage 8 V and power dissipation rating of 0.5 W is connected across a potential divider arranged with maximum potential drop across zener diode is as shown in the diagram. The value of protective resistance Rp is .................... $\Omega$.
Options:
228
Medium
For the forward biased diode characteristics shown in the figure, the dynamic resistance at ID = 3 mA will be __________ $\Omega$.
Options:
229
Easy
The typical output characteristics curve for a transistor working in the common-emitter configuration is shown in the figure.The estimated current gain from the figure is __________.
Options:
230
Medium
An npn transistor operates as a common emitter amplifier with a power gain of 106. The input circuit resistance is 100$\Omega and the output load resistance is 10 K\Omega. The common emitter current gain '\beta$' will be ________. (Round off to the Nearest Integer).
Options:
231
Medium
The value of power dissipated across the zener diode (Vz = 15V) connected in the circuit as shown in the figure is x $\times 10-$1 watt.The value of x, to the nearest integer, is __________.
Options:
232
Easy
In the logic circuit shown in the figure, if input A and B are 0 to 1 respectively, the output at Y would be 'x'.The value of x is ____________.
Options:
233
Medium
The zener diode has a Vz = 30V. The current passing through the diode for the following circuit is ________ mA.
Options:
234
Medium
The circuit contains two diodes each with a forward resistance of 50$\Omega and with infinite reverse resistance. If the battery voltage is 6V, the current through the 120\Omega$ resistance is ____________ mA.
Options:
235
Easy
In connection with the circuit drawn below, the value of current flowing through 2 k$\Omega resistor is _________ \times 10-$4 A.
Options:
236
Medium
The output characteristics of a transistor is shown in the figure. When VCE is 10V and IC = 4.0 mA, then value of $\beta $ac is __________.
Options:
237
Medium
The circuit shown below is working as a 8 V dc regulated voltage source. When 12 V is used as input, the power dissipated (in mW) in each diode is; (considering both zener diodes are identical) _________.
Options:
238
Medium
Both the diodes used in the circuit shown are assumed to be ideal and have negligible resistance when these are forward biased. Built in potential in each diode is 0.7 V. For the input voltages shown in the figure, the voltage (in Volts) at point A is __________.
Options:
239
Medium
For a common emitter configuration, if $\alpha and \beta have their usual meanings, the incorrect relationship between \alpha and \beta $ is :
Options:
A) \alpha = {\beta \over {1 + \beta }}
B) \alpha = {{{\beta ^2}} \over {1 + {\beta ^2}}}
C) {1 \over \alpha } = {1 \over \beta } + 1
D) \alpha = {\beta \over {1 - {\beta ^2}}}
239
Total Questions
112
Easy
127
Medium
0
Hard
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