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Physics
Semiconductor
Previous Years Questions

MCQ (Single Correct Answer)

Choose the correct statement about Zener diode :
Match List I with List II: .tg {border-collapse:collapse;border-spacing:0;} .tg td{border-color:black;border-style:solid;border-width:1px;font-famil...
Given below are two statements : Statement I: In a typical transistor, all three regions emitter, base and collector have same doping level. Statement...
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:...
The output $Y$ for the inputs $A$ and $B$ of circuit is given by Truth table of the shown circuit is:...
The output waveform of the given logical circuit for the following inputs A and B as shown below, is : ...
For the given logic gates combination, the correct truth table will be ...
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 onl...
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 ...
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 bi...
The logic gate equivalent to the given circuit diagram is :...
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R Assertion A : Photodiodes are preferably operate...
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 ...
Identify the solar cell characteristics from the following options :
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 $...
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 :...
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 $$B=...
In the given circuit the input voltage Vin is shown in figure. The cut-in voltage of p-n junction diode (D1 or D2) is 0.6 V. Which of the following ou...
In the following circuit, the correct relation between output (Y) and inputs A and B will be : ...
For using a multimeter to identify diode from electrical components, choose the correct statement out of the following about the diode :
Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R. Assertion A : n-p-n transistor permits more cur...
For a transistor to act as a switch, it must be operated in
Identify the correct Logic Gate for the following output (Y) of two inputs A and B. ...
The positive feedback is required by an amplifier to act an oscillator. The feedback here means :
The I-V characteristics of a p-n junction diode in forward bias is shown in the figure. The ratio of dynamic resistance, corresponding to forward bias...
Identify the logic operation performed by the given circuit: ...
The photodiode is used to detect the optical signals. These diodes are preferably operated in reverse biased mode because :
In the given figure, each diode has a forward bias resistance of 30$$\Omega$$ and infinite resistance in reverse bias. The current I1 will be :...
If VA and VB are the input voltages (either 5V or 0V) and V0 is the output voltage then the two gates represented in the following circuit (A) and (B)...
In the following logic circuit the sequence of the inputs A, B are (0, 0), (0, 1), (1, 0) and (1, 1). The output Y for this sequence will be :...
Choose the correct waveform that can represent the voltage across R of the following circuit, assuming the diode is ideal one :...
For a transistor $$\alpha$$ and $$\beta$$ are given as $$\alpha = {{{I_C}} \over {{I_E}}}$$ and $$\beta = {{{I_C}} \over {{I_B}}}$$. Then the correc...
For a transistor in CE mode to be used as an amplifier, it must be operated in :
Four NOR gates are connected as shown in figure. The truth table for the given figure is :...
Identify the logic operation carried out by the given circuit :-...
Statement I : By doping silicon semiconductor with pentavalent material, the electrons density increases.Statement II : The n-type semiconductor has n...
Find the truth table for the function Y of A and B represented in the following figure....
Identify the logic operation carried out....
Consider a situation in which reserve biased current of a particular P-N junction increases when it is exposed to a light of wavelength $$\le$$ 621 nm...
For the circuit shown below, calculate the value of Iz :...
The correct relation between $$\alpha$$ (ratio of collector current to emitter current) and $$\beta$$ (ratio of collector current to base current) of ...
Which one of the following will be the output of the given circuit?...
The output of the given combination gates represents :...
The following logic gate is equivalent to :...
Draw the output signal Y in the given combination of gates....
LED is constructed from Ga-As-P semiconducting material. The energy gap of this LED is 1.9 eV. Calculate the wavelength of light emitted and its colou...
For extrinsic semiconductors; when doping level is increased;
The truth table for the following logic circuit is :...
A 5V battery is connected across the points X and Y. Assume D1 and D2 to be normal silicon diodes. Find the current supplied by the battery if the +ve...
The logic circuit shown above is equivalent to :...
Given below are two statements :Statement I : PN junction diodes can be used to function as transistor, simply by connecting two diodes, back to back,...
Zener breakdown occurs in a p $$-$$ n junction having p and n both :
If an emitter current is changed by 4 mA, the collector current changes by 3.5 mA. The value of $$\beta$$ will be :
Identify the correct output signal Y in the given combination of gates (as shown) for the given inputs A and B. ...
Two Zener diodes (A and B) having breakdown voltages of 6 V and 4 V respectively, are connected as shown in the circuit below. The output voltage V0 v...
With increasing biasing voltage of a photodiode, the photocurrent magnitude :
Identify the operation performed by the circuit given below : ...
Take the breakdown voltage of the zener diode used in the given circuit as 6V. For the input voltage shown in figure below, the time variation of the ...
If a semiconductor photodiode can detect a photon with a maximum wavelength of 400 nm, then its band gap energy is : Planck’s constant h = 6.63 $$ \ti...
Which of the following will NOT be observed when a multimeter (operating in resistance measuring mode) probes connected across a component, are just r...
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 use...
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) ...
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...
In the given circuit, value of Y is : ...
Boolean relation at the output stage-Y for the following circuit is : ...
Which of the following gives a reversible operation?
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 ...
The truth table for the circuit given in the fig. is: ...
The transfer characteristic curve of a transistor, having input and output resistance 100 $$\Omega $$ and 100 k$$\Omega $$ respectively is shown in th...
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 ...
An npn transistor operates as a common emitter amplifier, with a power gain of 60 dB. The input circuit resistance is 100$$\Omega $$ and the output lo...
The logic gate equivalent to the given logic circuit is :- ...
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 acro...
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 ...
The reverse breakdown voltage of a Zener diode is 5.6 V in the given circuit. The current IZ through the Zener is : ...
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 ...
The output of the given logic circuit is : ...
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 throug...
In the given circuit the current through Zener Diode is close to: ...
For the circuit shown below, the current through the Zener diode is - ...
To get output 1 at R, for the given logic gate circuit the input values must be ...
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 change...
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 semiconducto...
In the given circuit, the current through zener diode is : ...
The reading of the ammeter for a silicon diode in the given circuit is : ...
Truth table for the following digital circuit will be : ...
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 resi...
The current gain of a common emitter amplifier is 69. If the emitter current is 7.0 mA, collector current is :
What is the conductivity of a semiconductor sale having electron concentration of $$5 \times {10^{18}}\,\,{m^{ - 3}},$$ hole concentration of $$5 \ti...
The V-I characteristic of a diode is shown in the figure. The ratio of forward to reverse bias resistance is : ...
In a common emitter amplifier circuit using an n-p-n transistor, the phase difference between the input and the output voltages will be:
The ratio (R) of output resistance r0, and the input resistance ri in measurements of input and output characteristics of a transistor is typically in...
A realistic graph depicting the variation of the reciprocal of input resistance in an input characteristics measurement in a commonemitter transistor ...
To get an output of 1 from the circuit shown in figure the input must be : ...
The truth table given in fig. represents : .tg {border-collapse:collapse;border-spacing:0;width:100%} .tg td{font-family:Arial, sans-serif;font-size...
An unknown transistor needs to be identified as a npn or pnp type. A multimeter, with + ve and − ve terminals, is used to measure resistance between d...
An experiment is performed to determine the I - V characteristics of a Zener diode, which has a protective resistance of R = 100 $$\Omega $$, and a ma...
If $$a, b, c, d$$ are inputs to a gate and $$x$$ is its output, then, as per the following time graph, the gate is : ...
Identify the semiconductor devices whose characteristics are given below, in the order $$(a), (b), (c), (d)$$ : ...
The current voltage relation of diode is given by $${\rm I} = \left( {{e^{100V/T}} - 1} \right)mA,$$ where the applied voltage $$V$$ is in volts and t...
The forward biased diode connection is:
A diode detector is used to detect an amplitude modulated wave of $$60\% $$ modulation by using a condenser of capacity $$250$$ picofarad in parallel ...
The $${\rm I}$$-$$V$$ characteristic of an $$LED$$ is
Truth table for system of four $$NAND$$ gates as shown in figure is: ...
The combination of gates shown below yields ...
The logic circuit shown below has the input waveforms $$'A'$$ and $$'B'$$ as shown. Pick out the correct output waveform. Output is ...
A $$p$$-$$n$$ junction $$(D)$$ shown in the figure can act as a rectifier. An alternating current source $$(V)$$ is connected in the circuit. The cur...
A working transistor with its three legs marked $$P,Q$$ and $$R$$ is tested using a multi-meter. No conduction is found between $$P$$ and $$Q$$. By co...
In the circuit below, $$A$$ and $$B$$ represent two inputs and $$C$$ represents the output. The circuit represents...
Carbon, silicon and germanium have four valence electrons each. At room temperature which one of the following statements is most appropriate ?
If in a $$p$$-$$n$$ junction diode, a square input signal of $$10$$ $$V$$ is applied as shown Then the output signal across $${R_L}$$ will be ...
In a common base mode of a transistor, the collector current is $$5.488$$ $$mA$$ for an emitter current of $$5.60mA.$$ The value of the base current a...
If the ratio of the concentration of electrons to that of holes in a semiconductor is $${7 \over 5}$$ and the ratio of currents is $${7 \over 4},$$ th...
A solid which is not transparent to visible light and whose conductivity increases with temperature is formed by
The circuit has two oppositively connected ideal diodes in parallel. What is the current following in the circuit? ...
In the following, which one of the diodes is reverse biased?
If the lattice constant of this semiconductor is decreased, then which of the following is correct? ...
The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than $$2480$$ $$nm$$ is incident on it. ...
In a full wave rectifier circuit operating from $$50$$ $$Hz$$ mains frequency, the fundamental frequency in the ripple would be
In a common base amplifier, the phase difference between the input signal voltage and output voltage is
When $$npn$$ transistor is used as an amplifer
For a transistor amplifier in common emitter configuration for load impedance of $$1k\,\Omega $$ $$\left( {{h_{fe}} = 50} \right.$$ and $$\left. {{h_{...
A piece of copper and another of germanium are cooled from room temperature to $$77K,$$ the resistance of
The manifestation of band structure in solids is due to
When $$p$$-$$n$$ junction diode is forward biased then
A strip of copper and another of germanium are cooled from room temperature to $$80K.$$ The resistance of
The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the
In the middle of the depletion layer of a reverse- biased $$p$$-$$n$$ junction, the
At absolute zero, Si acts as
Formation of covalent bonds in compounds exhibits
By increasing the temperature, the specific resistance of a conductor and a semiconductor
The energy band gap is maximum in
The part of a transistor which is most heavily doped to produce large number of majority carriers is

Numerical

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 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 ...
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 c...
In the circuit shown below, maximum zener diode current will be _________ $$\mathrm{mA}$$. ...
Two ideal diodes are connected in the network as shown in figure. The equivalent resistance between A and B is __________ $$\Omega$$. ...
The energy band gap of semiconducting material to produce violet (wavelength = 4000$$\mathop A\limits^o $$ ) LED is ______________ $$\mathrm{eV}$$. (R...
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...
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...
A transistor is used in an amplifier circuit in common emitter mode. If the base current changes by 100 $$\mu$$A, it brings a change of 10 mA in colle...
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 ...
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. ...
As per the given circuit, the value of current through the battery will be ____________ A. ...
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...
In the given circuit, the value of current IL will be ____________ mA. (When RL = 1k$$\Omega$$) ...
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 cha...
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 fluct...
A circuit is arranged as shown in figure. The output voltage V0 is equal to ................... V....
If the maximum value of accelerating potential provided by a ratio frequency oscillator is 12 kV. The number of revolution made by a proton in a cyclo...
For the given circuit, the power across Zener diode is .............. mW....
In a semiconductor, the number density of intrinsic charge carries at 27$$^\circ$$C is 1.5 $$\times$$ 1016/m3. If the semiconductor is doped with impu...
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 resista...
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 d...
For the forward biased diode characteristics shown in the figure, the dynamic resistance at ID = 3 mA will be __________ $$\Omega$$....
The typical output characteristics curve for a transistor working in the common-emitter configuration is shown in the figure.The estimated current gai...
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 r...
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 valu...
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 ____________. ...
The zener diode has a Vz = 30V. The current passing through the diode for the following circuit is ________ mA....
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...
In connection with the circuit drawn below, the value of current flowing through 2 k$$\Omega$$ resistor is _________ $$\times$$ 10$$-$$4 A....
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 __________. ...
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; (c...
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 ...

MCQ (More than One Correct Answer)

For a common emitter configuration, if $$\alpha $$ and $$\beta $$ have their usual meanings, the incorrect relationship between $$\alpha $$ and $$\bet...
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