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question_answer1)
When the forward bias voltage of a diode is changed from \[0.6\text{ }V\] to \[0.7\text{ }V,\] the current changes from \[5\text{ }mA\] to\[15\text{ }mA\]. Then its forward bias resistance is
A)
\[0.01\,\Omega \] done
clear
B)
\[0.1\,\Omega \] done
clear
C)
\[10\,\Omega \] done
clear
D)
\[100\,\Omega \] done
clear
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question_answer2)
The I-V characteristic of a P-N junction diode is shown below. The approximate dynamic resistance of the p-n junction when a forward bias of 2 volt is applied is
A)
\[1\,\Omega \] done
clear
B)
\[0.25\,\Omega \] done
clear
C)
\[0.5\,\Omega \] done
clear
D)
\[5\,\Omega \] done
clear
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question_answer3)
Zener breakdown in a semi-conductor diode occurs when
A)
forward current exceeds certain value done
clear
B)
reverse bias exceeds certain value done
clear
C)
forward bias is equal to certain value done
clear
D)
potential barrier is reduced to zero done
clear
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question_answer4)
The electric conductivity of an intrinsic semiconductor increases when the electromagnetic waves of wavelength equal or shorter than \[3895\text{ }nm\] is incident on it. The band gap of the semiconductor is
A)
\[0.2\text{ }eV\] done
clear
B)
\[0.3\text{ }eV\] done
clear
C)
\[1.0\text{ }eV\] done
clear
D)
\[1.5\,eV\] done
clear
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question_answer5)
A silicon diode has a threshold voltage of \[0.7\text{ }V\]. If an input voltage given by \[2\sin (\pi t)\] is supplied to a half wave rectifier circuit using this diode, the rectified output has a peak value of
A)
\[2V\] done
clear
B)
\[1.4V\] done
clear
C)
\[1.3V\] done
clear
D)
\[0.7\,V\] done
clear
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question_answer6)
A potential barrier of \[0.50\,V\] exists across a p-n junction. If the depletion region is \[5.0\times {{10}^{-7}}m\]wide, the intensity of the electric field in this region is
A)
\[1.0\times {{10}^{6}}\,V/m\] done
clear
B)
\[1.0\times {{10}^{5}}\,V/m\] done
clear
C)
\[2.0\times {{10}^{5}}\,V/m\] done
clear
D)
\[2.0\times {{10}^{6}}\,V/m\] done
clear
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question_answer7)
The concentration of hole - electron pairs in pure silicon at \[T=300\text{ }K\] is \[7\times {{10}^{15}}\]per cubic meter. Antimony is doped into silicon in a proportion of 1 atom in \[{{10}^{7}}\,Si\] atoms. Assuming that half of the impurity atoms contribute electron in the conduction band, calculate the factor by which the number of charge carriers increases due to doping. The number of silicon atoms per cubic meter is \[5\times {{10}^{28}}\]
A)
\[2.8\times {{10}^{5}}\] done
clear
B)
\[3.1\times {{10}^{2}}\] done
clear
C)
\[4.2\times {{10}^{5}}\] done
clear
D)
\[1.8\times {{10}^{5}}\] done
clear
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question_answer8)
A zener diode of voltage \[{{V}_{Z}}(=6V)\] is used to maintain a constant voltage across a load resistance \[{{R}_{L}}(=1000\,\,\Omega )\] by using a series resistance \[{{R}_{S}}(=100\,\Omega )\]. If the e.m.f. of source is \[E(=9\,V),\] what is the power being dissipated in Zener diode?
A)
\[0.144\]watt done
clear
B)
\[0.324\]watt done
clear
C)
\[0.244\]watt done
clear
D)
\[0.544\]watt done
clear
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question_answer9)
If the ratio of the concentration of electrons to that of holes in a semiconductor is \[\frac{7}{5}\] and the ratio of currents is \[\frac{7}{4},\] then what is the ratio of their drift velocities?
A)
\[\frac{5}{8}\] done
clear
B)
\[\frac{4}{5}\] done
clear
C)
\[\frac{5}{4}\] done
clear
D)
\[\frac{4}{7}\] done
clear
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question_answer10)
The circuit has two oppositively connected ideal diodes in parallel. What is the current flowing in the circuit?
A)
\[0.4A\] done
clear
B)
\[0.8\,A\] done
clear
C)
\[0.6\,A\] done
clear
D)
\[0.5\,A\] done
clear
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question_answer11)
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 \[0.1\text{ }A\] current passes through resistance then what is the voltage of the source?
A)
\[1.5\,V\] done
clear
B)
\[2.0\,V\] done
clear
C)
\[2.5\,V\] done
clear
D)
\[5\,V\] done
clear
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question_answer12)
If the lattice constant of this semiconductor is decreased, then which of the following is correct?
A)
All \[{{E}_{c}},{{E}_{g}},{{E}_{v}}\] increase done
clear
B)
\[{{E}_{c}}\] and \[{{E}_{v}}\] increase, but \[{{E}_{g}}\] decreases done
clear
C)
\[{{E}_{c}}\] and \[{{E}_{v}}\] decrease, but \[{{E}_{g}}\] increases done
clear
D)
All \[{{E}_{c}},{{E}_{g}},{{E}_{v}}\] decrease done
clear
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question_answer13)
In the following, which one of the diodes reverse biased?
A)
B)
C)
D)
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question_answer14)
A Zener diode is connected to a battery and a load as show below:
The currents, \[I,\,\,{{I}_{Z}}\] and \[{{I}_{L}}\] are respectively.
A)
\[15mA,\,\,5mA,\,\,10mA\] done
clear
B)
\[15mA,\,\,7.5mA,\,\,7.5mA\] done
clear
C)
\[12.5mA,\text{ }5mA,\text{ }7.5mA\] done
clear
D)
\[12.5mA,\text{ }7.5mA,\text{ }5mA\] done
clear
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question_answer15)
Suppose a 'n'-type wafer is creatd by doping \[Si\]crystal having \[5\times {{10}^{28}}atoms/{{m}^{3}}\] with 1 ppm concentration of As. On the surface 200 ppm Boron is added to create ?P' region in this wafer. Considering \[{{n}_{i}}=1.5\times {{10}^{6}}\,{{m}^{-3}}\] calculate the density of the minority charge carriers in the p regions.
A)
\[2.25\times {{10}^{7}}/{{m}^{3}}\] done
clear
B)
\[1.12\times {{10}^{3}}/{{m}^{3}}\] done
clear
C)
\[3.11\times {{10}^{6}}/{{m}^{3}}\] done
clear
D)
\[2.11\times {{10}^{5}}/{{m}^{3}}\] done
clear
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question_answer16)
Which of the following statements is incorrect?
A)
The drift current in a p-n junction is from the n-side to the p-side. done
clear
B)
Drift current is due to free electrons only. done
clear
C)
Silicon is preferred over germanium for making semiconductor devices. done
clear
D)
The energy gap in germanium is more than the energy gap in silicon. done
clear
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question_answer17)
For LED's to emit light in visible region of electromagnetic light, it should have energy band gap in the range of:
A)
\[0.1\,eV\] to \[0.4\,eV\] done
clear
B)
\[0.5\,eV\] to \[0.8\,eV\] done
clear
C)
\[0.9\,eV\] to \[1.6\,eV\] done
clear
D)
\[1.7\,eV\] to \[3.0\,eV\] done
clear
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question_answer18)
When a potential difference is applied across, the current passing through
A)
an insulator at OK is maximum done
clear
B)
a semiconductor at OK is zero done
clear
C)
a metal at OK is finite done
clear
D)
a P-N diode at 300K is zero, if it is neverse biased done
clear
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question_answer19)
The circuit shown in following figure contains two diode \[{{D}_{1}}\] and \[{{D}_{2}}\] each with a forward resistance of 50 ohms and with infinite backward resistance. If the battery voltage is \[6\text{ }V,\] the current through the 100 ohm resistance (in amperes) is
A)
zero done
clear
B)
\[0.02\] done
clear
C)
\[0.03\] done
clear
D)
\[0.036\] done
clear
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question_answer20)
Pure \[Si\] at \[500K\] has equal number of electron \[({{n}_{e}})\] and hole \[({{n}_{h}})\] concentrations 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)
n-type with electron concentration \[{{n}_{e}}=5\times {{10}^{22}}{{m}^{-3}}\] done
clear
B)
p-type with electron concentration \[{{n}_{e}}=2.5\times {{10}^{10}}{{m}^{-3}}\] done
clear
C)
n-type with electron concentration \[{{n}_{e}}=2.5\times {{10}^{23}}{{m}^{-3}}\] done
clear
D)
p-type having electron concentration \[{{n}_{e}}=5\times {{10}^{9}}{{m}^{-3}}\] done
clear
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question_answer21)
When p-n junction diode is forward biased then
A)
both the depletion region and barrier height are reduced done
clear
B)
the depletion region is widened and barrier height is reduced done
clear
C)
the depletion region is reduced and barrier height is increased done
clear
D)
Both the depletion region and barrier height are increased done
clear
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question_answer22)
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
A)
B)
C)
D)
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question_answer23)
In a p-type semiconductor the acceptor level is situated \[60\text{ }meV\] above the valence band. The maximum wavelength of light required to produce a hole will be
A)
\[0.207\times {{10}^{-5}}m\] done
clear
B)
\[2.07\times {{10}^{-5}}m\] done
clear
C)
\[20.7\times {{10}^{-5}}m\] done
clear
D)
\[2075\times {{10}^{-5}}m\] done
clear
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question_answer24)
In a fall wave rectifier circuit operating from \[150\text{ }Hz\]mains frequency, the fundamental frequency in the ripple would be
A)
\[25\text{ }Hz\] done
clear
B)
\[50\text{ }Hz\] done
clear
C)
\[70.7\text{ }Hz\] done
clear
D)
\[\text{300 }Hz\] done
clear
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question_answer25)
Carbon, silicon and germanium have four valence electrons each. At room temperature which one of the following statements is most appropriate?
A)
The number of free electrons for conduction is significant only in \[Si\] and \[Ge\] but small in C. done
clear
B)
The number of free conduction electrons is significant in C but small in \[Si\] and \[Ge\]. done
clear
C)
The number of free conduction electrons is negligibly small in all the three. done
clear
D)
The number of free electrons for conduction is significant in all the three. done
clear
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question_answer26)
A \[2-V\] battery is connected across the points A and B as shown in the figure given below. Assuming that the resistance of each diode is zero in forward bias, and infinity in reverse bias, the current supplied by the battery when its positive terminal is connected to A, is
A)
\[0.2A\] done
clear
B)
\[0.4A\] done
clear
C)
\[0.3A\] done
clear
D)
\[0.1A\] done
clear
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question_answer27)
The correct statement is
A)
A p-type semiconductors is a negative type crystal. done
clear
B)
A p- type semiconductor is a charged crystal. done
clear
C)
The diffusion current in a p-n junction is from the p-side to the n-side. done
clear
D)
The diffusion current in a p-n junction is smaller than the drift current when the junction is in forward biased. done
clear
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question_answer28)
Different voltages are applied across a P-N junction and the currents are measured for each value. Which of the following graphs is obtained between voltage and current
A)
B)
C)
D)
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question_answer29)
On doping germanium with donor atoms of density \[{{10}^{17}}\,c{{m}^{-3}}\] its conductivity in mho/cm will be [Given \[{{\mu }_{e}}=3800\,c{{m}^{2}}V-s\] and \[{{n}_{i}}=2.5\times {{10}^{13}}c{{m}^{-13}}\]]
A)
\[30.4\] done
clear
B)
\[60.8\] done
clear
C)
\[91.2\] done
clear
D)
\[121.6\] done
clear
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question_answer30)
In a p-n junction having depletion layer of thickness \[{{10}^{-6}}m\] the potential across it is \[0.1\text{ }V\]. The electric field is
A)
\[{{10}^{7}}V/m\] done
clear
B)
\[{{10}^{-6}}V/m\] done
clear
C)
\[{{10}^{5}}V/m\] done
clear
D)
\[{{10}^{-5}}V/m\] done
clear
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question_answer31)
The intrinsic conductivity of germanium at \[27{}^\circ \] is \[2.13\text{ }mho\text{ }{{m}^{-1}}\] and mobilities of electrons and holes are \[0.38\] and \[0.18\,{{m}^{2}}\,{{V}^{-1}}\,{{s}^{-1}}\]respectively. The density of charge carriers is
A)
\[2.37\times {{10}^{19}}{{m}^{-3}}\] done
clear
B)
\[3.28\times {{10}^{19}}{{m}^{-3}}\] done
clear
C)
\[7.83\times {{10}^{19}}{{m}^{-3}}\] done
clear
D)
\[8.47\times {{10}^{19}}{{m}^{-3}}\] done
clear
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question_answer32)
Currents flowing in each of the circuits A and B respectively are
A)
\[1\,A,\,2A\] done
clear
B)
\[2\,A,\,1A\] done
clear
C)
\[4\,A,\,2A\] done
clear
D)
\[2\,A,\,4A\] done
clear
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question_answer33)
By increasing the temperature, the specific resistance of a conductor and a semiconductor
A)
increases for both done
clear
B)
decreases for both done
clear
C)
increases, decreases done
clear
D)
decreases, increases done
clear
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question_answer34)
A zener diode, having breakdown voltage equal to \[15V,\] is used in a voltage regulator circuit shown in figure. The current through the diode is
A)
\[10\,mA\] done
clear
B)
\[15\,mA\] done
clear
C)
\[20\,mA\] done
clear
D)
\[5\,mA\] done
clear
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question_answer35)
The ratio of electron and hole currents in a semiconductor is \[7/4\] and the ratio of drift velocities of electrons and holes is \[5/4,\] then ratio of concentrations of electrons and holes will be
A)
\[5/7\] done
clear
B)
\[7/5\] done
clear
C)
\[25/49\] done
clear
D)
\[49/25\] done
clear
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question_answer36)
A d.c. battery of V volt is connected to a series combination of a resistor R and an ideal diode D as shown in the figure below. The potential difference across R will be
A)
2V when diode is forward biased done
clear
B)
zero when diode is forward biased done
clear
C)
V when diode is reverse biased done
clear
D)
V when diode is forward biased done
clear
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question_answer37)
In fig., the input is across the terminals A and C and the output is across B and D. Then the output is
A)
zero done
clear
B)
same as the input done
clear
C)
half wave rectified done
clear
D)
full wave rectified done
clear
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question_answer38)
Assuming the diodes to be of silicon with for- ward resistance zero, the current I in the following circuit is
A)
\[0\] done
clear
B)
\[9.65\,mA\] done
clear
C)
\[10\,mA\] done
clear
D)
\[10.36\,mA\] done
clear
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question_answer39)
An experiment is performed to determine the \[1-V\]characteristics of a Zener diode, which has a protective resistance of \[R=100\,\Omega ,\] and a maximum power of dissipation rating of \[1W\]. The minimum voltage range of the DC source in the circuit is:
A)
\[0-5\,V\] done
clear
B)
\[0-24\,V\] done
clear
C)
\[0-12\,V\] done
clear
D)
\[0-8\,V\] done
clear
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question_answer40)
In germanium the energy gap is about\[0.75\text{ }eV\]. The wavelength of light which germanium starts absorbing is
A)
\[5000\text{ }\overset{o}{\mathop{A}}\,\] done
clear
B)
\[1650\text{ }\overset{o}{\mathop{A}}\,\] done
clear
C)
\[16500\text{ }\overset{o}{\mathop{A}}\,\] done
clear
D)
\[165000\text{ }\overset{o}{\mathop{A}}\,\] done
clear
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question_answer41)
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)
\[0.8\,mA\] done
clear
B)
\[0.6\,mA\] done
clear
C)
\[0.4\,mA\] done
clear
D)
\[1\,mA\] done
clear
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question_answer42)
Which one of the following statement is false?
A)
Pure \[Si\] doped with trivalent impurities gives a p-type semiconductor done
clear
B)
Majority carriers in a n-type semiconductor are holes done
clear
C)
Minority carriers in a p-type semiconductor are electrons done
clear
D)
The resistance of intrinsic semiconductor decreases with increase of temperature done
clear
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question_answer43)
If a battery of \[5\,V\] is connected across a plate of the semiconductor of area \[2\times {{10}^{-4}}\text{ }{{m}^{2}}\] and of thickness \[1.2\times {{10}^{-3}}m,\] then the current flowing through the plate is
A)
\[0.32\,mA\] done
clear
B)
\[0.64\,mA\] done
clear
C)
\[1.28\,mA\] done
clear
D)
\[2.56\,mA\] done
clear
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question_answer44)
In a triode, \[{{g}_{m}}=2\times {{10}^{-3}}oh{{m}^{-1}};\] \[\mu =42;\] resistance of load, \[R=50\] kilo ohm. The voltage amplification obtained from this triode will be
A)
\[30.42\] done
clear
B)
\[29.57\] done
clear
C)
\[28.18\] done
clear
D)
\[27.15\] done
clear
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question_answer45)
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 insulator done
clear
B)
a metal done
clear
C)
an n-type semiconductor done
clear
D)
a p-type semiconductor done
clear
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question_answer46)
The electric conductivity of an intrinsic semiconductor increases when the electromagnetic waves of wavelength equal or shorter than \[2475\text{ }nm\] is incident on it. The charge carrier concentration of this semiconductor at room temperature is \[1.6\times {{10}^{16}}{{m}^{-3}}\] and the mobilities of electrons and holes at the same temperature are \[0.4\,{{m}^{2}}\,{{V}^{-1}}\,{{S}^{-1}}\] and \[0.2\,{{m}^{2}}\,{{V}^{-1}}\,{{S}^{-1}}\] respectively Regarding these information the band gap B is
A)
\[B=0.5\,eV\] done
clear
B)
\[B=1.3\,eV\] done
clear
C)
\[B=1.54\times {{10}^{-3}}eV\] done
clear
D)
None of these done
clear
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question_answer47)
A transistor is connected in common -emitter configuration. The collector supply is \[8\,V\] and the voltage drop across a resistor of \[800\,W\] in the collector is \[0.5\text{ }V\]. If the current gain factor \[\alpha \] is\[0.96\]. Find the base current.
A)
\[26\,\mu A\] done
clear
B)
\[16\,\mu A\] done
clear
C)
\[10\,\mu A\] done
clear
D)
\[5\,\mu A\] done
clear
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question_answer48)
Copper, a monovalent, has molar mass \[63.54g/mol\]and density \[8.96\text{ }g/c{{m}^{3}}\]. What is the number density n of conduction electron in copper?
A)
\[3.2\times {{10}^{20}}\,{{m}^{-3}}\] done
clear
B)
\[8.49\times {{10}^{26}}\,{{m}^{-3}}\] done
clear
C)
\[6.2\times {{10}^{31}}\,{{m}^{-3}}\] done
clear
D)
None done
clear
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question_answer49)
A \[pnp\] transistor is used in common-emitter mode in an amplifier circuit. A change of \[40\mu A\] in the base current brings a change of \[2\text{ }mA\] in collector current and \[0.04\text{ }V\] in base emitter voltage. Which of the following is the correct value of the input resistor \[{{R}_{in}}\]?
A)
\[{{R}_{in}}=9k\Omega \] done
clear
B)
\[{{R}_{in}}=75\,k\Omega \] done
clear
C)
\[{{R}_{in}}=1\,k\Omega \] done
clear
D)
None of these done
clear
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question_answer50)
The \[Si\] diode and the \[Ge\] diode conduct at \[0.7\,V\]and \[0.3\,V\] respectively, in the circuit given below:
If now the \[Ge\] diode connection are reversed, what will be the new value of i'
A)
\[i'=15.8\,mA\] done
clear
B)
\[i'=6.2\,mA\] done
clear
C)
\[i'=1.17\,mA\] done
clear
D)
\[i'=2.26\,mA\] done
clear
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question_answer51)
A 5V battery may be connected across the points A and B as shown in figure. Assume that the resistance of each diode is zero in forward bias and infinity in reverse bias. Find the current \[{{i}_{2}}\] by the battery if the positive terminal of the battery is connected to the point B.
A)
\[{{i}_{2}}=1.3A\] done
clear
B)
\[{{i}_{2}}=2.8A\] done
clear
C)
\[{{i}_{2}}=0.25A\] done
clear
D)
\[{{i}_{2}}=0.75A\] done
clear
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question_answer52)
A potential barrier of \[0.3\] Volt exists across a p-n junction. The depletion region is 1 pm wide. The intensity of electric field in this region is E. If electron with speed \[5\times {{10}^{5}}m/s\] approaches this p-n junction from n-side, what will be its speed V on entering the p-side?
A)
\[V=12\times {{10}^{5}}m/s\] done
clear
B)
\[V=1\times {{10}^{4}}m/s\] done
clear
C)
\[V=3.8\times {{10}^{5}}m/s\] done
clear
D)
\[V=1.6\times {{10}^{4}}m/s\] done
clear
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question_answer53)
A npn transistor in a common emitter mode is used as a simple voltage amplifier with a collector current of \[4mA\]. the terminal of a \[8V\] battery is connected to the collector through a load resistance \[{{R}_{L}}\] and to the base through a resistance \[{{R}_{B}}\]. The collector emitter voltage \[{{V}_{CE}}=4V,\] base-emitter voltage \[{{V}_{BE}}=0.6\] and the base current amplification factor \[{{\beta }_{dc}}=100,\]calculate the value of \[{{R}_{B}}.\]
A)
\[{{R}_{B}}=15\,k\Omega \] done
clear
B)
\[{{R}_{B}}=200\,k\Omega \] done
clear
C)
\[{{R}_{B}}=1\,k\Omega \] done
clear
D)
\[{{R}_{B}}=185\,k\Omega \] done
clear
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question_answer54)
In a common emitter (CE) amplifier having a voltage gain G, the transistor used has trans conductance \[0.03\] mho and current gain 25. If the above transistor is replaced with another one with trans conductance \[0.02\] mho and current gain 20, the voltage gain will be
A)
\[1.5\,G\] done
clear
B)
\[\frac{1}{3}\,G\] done
clear
C)
\[\frac{5}{4}\,G\] done
clear
D)
\[\frac{2}{3}\,G\] done
clear
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question_answer55)
The current gain in the common emitter 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)
\[300\] done
clear
B)
\[500\] done
clear
C)
\[200\] done
clear
D)
\[100\] done
clear
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question_answer56)
A transistor connected in common emitter con- figuration has input resistance \[{{R}_{B}}=2\,k\Omega \] and load resistance of \[5\,k\Omega \]. If \[\beta =60\] and an input signal \[12\text{ }mV\] is applied, calculate the voltage gain, the power gain and the value of output voltage
A)
\[{{A}_{V}}=150,\,\,{{V}_{out}}=1.8\,V,\] and power gain \[=9000\] done
clear
B)
\[{{A}_{V}}=20,\,{{V}_{out}}=1V,\]and power gain \[=2000\] done
clear
C)
\[{{A}_{V}}=150,\,{{V}_{out}}=1.5V,\] and power gain \[=8500\] done
clear
D)
\[{{A}_{V}}=20,\,{{V}_{out}}=1.5V,\] and power gain\[=2000\] done
clear
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question_answer57)
If the given transistor is used as an amplifier then for input resistance of \[80\,\Omega \] and load resistance of \[16\,k\Omega ,\] the output voltage corresponding to the input voltage of \[12mV\] will be
A)
\[37.5\,mV\] done
clear
B)
\[37500\,V\] done
clear
C)
\[300\,V\] done
clear
D)
\[300\,mV\] done
clear
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question_answer58)
An NPN-transistor circuit is arranged as shown in figure. It is
A)
a common base amplifier circuit done
clear
B)
a common emitter amplifier circuit done
clear
C)
a common collector amplifier circuit done
clear
D)
neither of the above done
clear
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question_answer59)
A npn transistor is connected in common emitter configuration in a given amplifier. A load resistance of \[800\,\Omega \] is connected in the collector circuit and the voltage drop across it is\[0.8\text { } V\]. If the current amplification factor is \[0.96\] and the input resistance of the circuit is \[192\Omega, \]the voltage gain and the power gain of the amplifier will respectively be:
A)
\[4,\,\,3.84\] done
clear
B)
\[3.69,\,\,3.84\] done
clear
C)
\[4,\,\,4\] done
clear
D)
\[4,\,\,3.69\] done
clear
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question_answer60)
A transistor can be used as an amplifier when
A)
emitter is forward biased and collector is reverse biased done
clear
B)
both are reverse biased done
clear
C)
both emitter and collector are forward done
clear
D)
None of these done
clear
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question_answer61)
In the case of a common emitter transistor amplifier the ratio of the collector current to the emitter current \[{{I}_{c}}/{{I}_{e}}\] is \[0.96\]. The current gain of the amplifier is
A)
\[6\] done
clear
B)
\[48\] done
clear
C)
\[24\] done
clear
D)
\[12\] done
clear
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question_answer62)
In a npn transistor \[{{10}^{10}}\] electrons enter the emitter in\[{{10}^{-6}}s.\] \[4%\] of the electrons are lost in the base. The current transfer ratio will be
A)
\[0.98\] done
clear
B)
\[0.97\] done
clear
C)
\[0.96\] done
clear
D)
\[0.94\] done
clear
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question_answer63)
The input resistance of a silicon transistor is\[100\text{ }W\]. Base current is changed by \[40\mu A\] which results in a change in collector current by \[2\text{ }mA\]. This transistor is used as a common emitter amplifier with a load resistance of \[4\,K\Omega \]. The voltage gain of the amplifier is:
A)
\[2000\] done
clear
B)
\[3000\] done
clear
C)
\[4000\] done
clear
D)
\[1000\] done
clear
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question_answer64)
For transistor action Base, emitter and collector regions should have similar size and doping concentrations. The base region must be very thin and lightly doped. The eimtter-base junction is forward biased and base-collector junction is reverse based. Both the emitter-base junction as well as the base-collector junction are forward biased.
A)
(3) and (4) done
clear
B)
(4) and (1) done
clear
C)
(1) and (2) done
clear
D)
(2) and (3) done
clear
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question_answer65)
In the following common emitter configuration an NPN transistor with current gain \[\beta =100\] is used. The output voltage of the amplifier will be
A)
\[10\,\,mV\] done
clear
B)
\[0.1\text{ }V\] done
clear
C)
\[1.0\text{ }V\] done
clear
D)
\[10\text{ }V\] done
clear
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question_answer66)
The transfer ratio \[\beta \] of a transistor is 50. The input resistance of the transistor when used in the common emitter configuration is 1 kn. The peak value of the collector A.C. current for an A.C. input voltage of \[0.01\text{ }V\] peak is
A)
\[100\,\mu A\] done
clear
B)
\[0.01\,mA\] done
clear
C)
\[0.25\,mA\] done
clear
D)
\[500\,\mu A\] done
clear
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question_answer67)
In a common base mode of a transistor, the collector current is \[5.488\text{ }mA\] for an emitter current of \[5.60\text{ }mA\]. The value of the base current amplification factor \[(\beta )\] will be
A)
\[49\] done
clear
B)
\[50\] done
clear
C)
\[51\] done
clear
D)
\[48\] done
clear
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question_answer68)
A transistor has \[\beta =40.\]A change in base current of \[100\,\mu A,\] produces change in collector current
A)
\[40\times 100\] microampere done
clear
B)
\[(100-40)\] microampere done
clear
C)
\[(100+40)\] microampere done
clear
D)
\[100/40\]microampere done
clear
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question_answer69)
Transfer characteristics [output voltage \[({{V}_{0}})\] vs input voltage \[({{V}_{1}})\]] for a base biased transistor in CE configuration is as shown in the figure. For using transistor as a switch, it is used
A)
in region (III) done
clear
B)
both in region (I) and (II) done
clear
C)
in region (II) done
clear
D)
in region (I) done
clear
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question_answer70)
When NPN transistor is used as an amplifier
A)
electrons move from base to emitter done
clear
B)
holes move from emitter to base done
clear
C)
electrons move from collector to base done
clear
D)
holes move from base to emitter done
clear
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question_answer71)
The ratio of work function and temperature of two emitters are \[1:2,\] then the ratio of current densities obtained by them will be
A)
\[4:1\] done
clear
B)
\[2:1\] done
clear
C)
\[1:2\] done
clear
D)
\[1:4\] done
clear
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question_answer72)
In a common emitter transistor amplifier the audio signal voltage across the collector is\[3V\]. The resistance of collector is \[3\,k\Omega \]. If current gain is 100 and the base resistance is \[2\,k\Omega ,\] the voltage and power gain of the amplifier is
A)
15 and 200 done
clear
B)
150 and 15000 done
clear
C)
20 and 2000 done
clear
D)
200 and 1000 done
clear
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question_answer73)
A transistor has a base current of \[1\text{ }mA\] and emitter current \[90\text{ }mA\]. The collector current will be
A)
\[90\text{ }mA\] done
clear
B)
\[\text{1 }mA\] done
clear
C)
\[\text{89 }mA\] done
clear
D)
\[\text{91 }mA\] done
clear
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question_answer74)
In an experiment with npn transistor amplifier in common emitter configuration, the current gain of the transistor is 100. If the collector current changes by \[1mA,\] what will be the change in emitter current?
A)
\[1.1\,mA\] done
clear
B)
\[1.01\,mA\] done
clear
C)
\[0.01\,mA\] done
clear
D)
\[10\,mA\] done
clear
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question_answer75)
In common emitter amplifier the \[\frac{{{I}_{c}}}{{{I}_{e}}}\] is\[0.98\]. The current gain will be
A)
\[4.9\] done
clear
B)
\[7.8\] done
clear
C)
\[49\] done
clear
D)
\[78\] done
clear
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question_answer76)
For a common base amplifier, the values of resistance gain and voltage gain are 3000 and 2800 respectively. The current gain will be
A)
\[1.1\] done
clear
B)
\[0.98\] done
clear
C)
\[0.93\] done
clear
D)
\[0.83\] done
clear
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question_answer77)
In a transistor, the change in base current from \[100\mu A\] to \[125\mu A\] causes a change in collector current from \[5\text{ }mA\] to \[7.5\text{ }mA,\] keeping collector- to-emitter voltage constant at\[10\text{ }V\]. What is the current gain of the transistor?
A)
\[200\] done
clear
B)
\[100\] done
clear
C)
\[50\] done
clear
D)
\[25\] done
clear
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question_answer78)
A common emitter amplifier has a voltage gain of 50, an input impedance of \[100\Omega \] and an output impedance of \[200\Omega \]. The power gain of the amplifier is
A)
\[1000\] done
clear
B)
\[1250\] done
clear
C)
\[100\] done
clear
D)
\[500\] done
clear
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question_answer79)
Current gain of a transistor in common base mode is\[0.95\]. Its value in common emitter mode is
A)
\[0.95\] done
clear
B)
\[1.5\] done
clear
C)
\[19\] done
clear
D)
\[{{(19)}^{-1}}\] done
clear
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question_answer80)
The current gain in transistor in common base mode is\[0.99\]. To change the emitter current by \[5\,mA,\] the necessary change in collector will be
A)
\[0.196\,mA\] done
clear
B)
\[2.45\,mA\] done
clear
C)
\[4.95\,mA\] done
clear
D)
\[5.1mA\] done
clear
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question_answer81)
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)
\[0.62\,V\] done
clear
B)
\[6.2\,V\] done
clear
C)
\[62\,V\] done
clear
D)
\[620\,V\] done
clear
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question_answer82)
What is the voltage gain in a common emitter amplifier, where input resistance is \[3\,\Omega \] and load resistance \[24\,\Omega ,\] \[\beta =0.6\]?
A)
\[8.4\] done
clear
B)
\[4.8\] done
clear
C)
\[2.4\] done
clear
D)
\[480\] done
clear
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question_answer83)
A transistor is operated in common emitter configuration at \[{{V}_{C}}=2V\] such that a change in the base current from \[100\,\mu A\] to \[300\,\mu A\] produces a change in the collector current from \[10\,mA\] to\[20\,mA\]. The current gain is
A)
\[50\] done
clear
B)
\[75\] done
clear
C)
\[100\] done
clear
D)
\[25\] done
clear
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question_answer84)
The figure shows a logic circuit with two inputs A and B and the output C. The voltage wave forms across A, B and C are as given. The logic gate circuit is:
A)
OR gate done
clear
B)
NOR gate done
clear
C)
AND gate done
clear
D)
NAND gate done
clear
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question_answer85)
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
A)
\[0,0\] done
clear
B)
\[0,\,\,1\] done
clear
C)
\[1,\,\,0\] done
clear
D)
\[1,\,\,1\] done
clear
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question_answer86)
The following circuit represents
A)
OR gate done
clear
B)
XOR gate done
clear
C)
AND gate done
clear
D)
NAND gate done
clear
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question_answer87)
In the circuit below, A and B represent two inputs and C represents the output. The circuit represents
A)
NOR gate done
clear
B)
AND gate done
clear
C)
NAND gate done
clear
D)
OR gate done
clear
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question_answer88)
What will be the input of A and B for the Boolean expression \[(\overline{A+B}.()\overline{A.B\,\,\,})=1\]
A)
\[0,\,\,0\] done
clear
B)
\[0,\,\,1\] done
clear
C)
\[1,\,\,0\] done
clear
D)
\[1,\,\,1\] done
clear
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question_answer89)
The logic circuit shown below has the input waveforms 'A' and 'B' as shown. Pick out the correct output waveform.
Output is:
A)
B)
C)
D)
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question_answer90)
A system of four gates is set up as shown. The 'truth table' corresponding to this system is :
A)
B)
C)
D)
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question_answer91)
The circuit is equivalent to
A)
NOR gate done
clear
B)
OR gate done
clear
C)
AND gate done
clear
D)
NAND gate done
clear
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question_answer92)
The combination of gates shown below yields
A)
OR gate done
clear
B)
NOT gate done
clear
C)
XOR gate done
clear
D)
NAND gate done
clear
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question_answer93)
The output of an OR gate is connected to both the inputs of a NAND gate. The combination will serve as a:
A)
NOT gate done
clear
B)
NOR gate done
clear
C)
AND gate done
clear
D)
OR gate done
clear
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question_answer94)
The forward biased diode connection is:
A)
B)
C)
D)
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question_answer95)
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:
A)
\[5.48\text{ }V/m\] done
clear
B)
\[7.75\text{ }V/m\] done
clear
C)
\[1.73\text{ }V/m\] done
clear
D)
\[2.45\text{ }V/m\] done
clear
View Solution play_arrow