CBSE Questions for Class 12 Medical Physics Semiconductor Electronics: Materials, Devices And Simple Circuits Quiz 8 - MCQExams.com

LEDs are better than conventional incandescent power lamps because:
  • LEDs have higher efficiency.
  • LEDs look beautiful.
  • LEDs are cheap.
  • all of the above.
According to Moore's Law:
  • The memory capacity of a chip is constant.
  • The memory capacity of a chip doubles every one and a half-years.
  • The memory capacity of a chip increases by ten times every one and a half-years.
  • The memory capacity of chip decreases with time.
Choose the correct statements:
  • It is easier to fabricate $$10000$$ AND gates using circuit components than on an integrated chip.
  • It is easier to fabricate $$10000$$ AND gates on an integrated chip than fabricating them using circuit components.
  • It is easier to fabricate a single AND gate using circuit components as compared to on an IC.
  • It is easier to fabricate a single AND gate on an IC as compared to using circuit components.
Which of the following is/are true regarding  breakdown voltage of Zener diode?
  • If the reverse bias voltage across a p-n junction diode is increased, at a particular voltage the reverse current suddenly decreases to a large value
  • The holes in the n-side and the conduction electrons in the p-side are accelerated due to the reverse bias voltage.
  • The voltage at which the rate of creation of hole-electron pairs is increased leading to the increased current is called avalanche breakdown
  • None of the above
Choose the correct statement:
  • Integrated circuits are less efficient in performance at all voltages.
  • Integrated circuits are more efficient in performance at low voltages.
  • Integrated circuits are less efficient in performance at high voltages.
  • Performance of an integrated circuit is independent of the magnitude of applied voltage.
The conductivity of a semi conductor is:
  • Greater than the conductivity of metals.
  • Less than the conductivity of metals.
  • Equal to the conductivity of metals.
  • Intermediate between the conductivity of metals and insulators.
Identify an IC:
The conductivity of a semi conductor can be increased by:
  • Heating the semi conductor
  • Doping the semi conductor
  • Both (a) and (b)
  • None
Production of ICs is preferred in industrial scales because:
  • it reduces the cost of production.
  • it makes the task of fabrication of a circuit easier.
  • it improves the efficiency of the circuit.
  • specifications of a circuit is same for all applications.
Which of the following is an advantage of a conventional circuit over integrated circuit?
  • They are fast.
  • They have higher power handling capability.
  • They are large in size.
  • All of the above.
In a n - type semi conductors which of the following statement is true:
  • Electrons are majority carrier and trivalent impurity are the dopants.
  • Electrons are minority carrier and pentavalent atoms are dopants.
  • Holes are minority carrier and pentavalent atoms are dopants.
  • Holes are majority carrier and trivalent atoms are the dopants.
Fill in the blank.
The following truth table with $$A$$ and $$B$$ as inputs is for _________ gate.
ABOutput
101
110
011
000
  • AND
  • OR
  • XOR
  • NOR
The given truth table is for
InputInputOutput
ABY
$$0$$$$0$$$$1$$
$$0$$$$1$$$$1$$
$$1$$$$0$$$$1$$
$$1$$$$1$$$$0$$
  • AND gate
  • OR gate
  • NAND gate
  • NOR gate
If $$\alpha$$-current gain of a transistor is 0.What is the value of $$\beta$$-current gain of the transistor?
  • 0.49
  • 49
  • 4.9
  • 5
A NOR gate and a NAND gate are connected as shown in the figure. Two different sets of inputs are given to this set up. In the first case, the input to the gates are A=0, B=0, C=In the second case, the inputs are A=1, B=0, C=The output D in the first case and second case respectively are
574281.PNG
  • 0 and 0
  • 0 and 1
  • 1 and 0
  • 1 and 1

The addition of pentavalent impurities  ________ of the semiconductor.
  • brings no change to the conductivity
  • decreases the conductivity
  • increases the conductivity
  • reduces the formation of free electrons
What change could be seen when dopant atoms are added to an intrinsic semiconductor?
  • It will change the proton and hole carrier concentrations of the semiconductor
  • It will change the temperature of the semiconductor
  • It will change the electron and hole carrier concentrations of the semiconductor
  • It will decrease the formation of free electrons in the semiconductor
Energy band gap between valence band and conduction band for insulator is:
  • Zero
  • greater than $$9\ eV$$
  • less than conductors
  • approximately $$1\ eV$$
Energy band gap between valence band and conduction band for conductor is:
  • more than semiconductors
  • Zero
  • more than insulators
  • None of these
Conductors are materials having an electrical conductivity :
  • greater than $$10^3$$ S/cm
  • between $$10^{-8}\ to \ 10^3$$ S/cm
  • equal to $$10^{-8}$$ S/cm
  • Zero
Energy band gap between valence band and conduction band for semiconductor is:
  • approximately 1 eV
  • less than conductors
  • equal to conductors
  • more than insulator
Match the following
a) p-type semiconductor1) Pure semiconductor
b) Intrinsic semiconductor2) Doped with impurity
c) Extrinsic semiconductor3) majority carriers are electrons
d) n-type semiconductor4) majority carriers are holes
  • a-3,b-2,c-4,d-1
  • a-1,b-2,c-4,d-3
  • a-4,b-1,c-2,d-3
  • a-2,b-1,c-4,d-3
Semiconductors are materials having an electrical conductivity :
  • Less than insulators
  • between $$10^{-8}\ S/cm \ to \ 10^3\ S/cm$$
  • Equal to zero
  • Greater than $$10^3\ S/cm$$
Insulators are materials having an electrical conductivity equal to:
  • Between $$10^{-8}$$ S/cm to $$10^{3}$$ S/cm
  • $$<\ 10^{-8}$$ S/cm
  • Equal to $$ 10^{3}$$ S/cm
  • $$>\ 10^{3}$$ S/cm
The following symbol represents
596726_77b5bbe43cdb4b6aaa14b86538dc531d.png
  • NAND gate
  • NOT gate
  • AND gate
  • OR gate
A proper combination of $$3$$ NOT and $$1$$ AND gates is shown. If $$A=0$$, $$B=1$$, $$C=1$$ then the output of this combination is
579976_727c33d7880748ddbfd30fc33d9ad0d3.png
  • $$1$$
  • Zero
  • Not predictable
  • None of these
The drift current in a $$p-n$$ junction diode is
  • motion of charge carriers due to the electric field
  • motion of charge carriers due to the charge concentration gradient
  • in same direction as the diffusion current
  • opposite in direction to the diffusion current
 The thickness of depletion region is of the order of 
  • $$0.1 \mu m$$
  • $$1 \mu m$$
  • $$0.1 mm$$
  • $$1 mm$$
The process that occur during formation of a $$p-n$$ junction is
  • diffusion
  • doping
  • drift
  • depletion
The space-charge region on either side of the junction together is known as depletion region because 
  • neither electrons nor holes exist in this region.
  • the electrons and holes taking part in the initial movement across the junction freed the region of its free charges.
  • the electrons and holes in this region are immobile.
  • None of these
Across the depletion region, there is a barrier potential which 
  • prevents the movement of electron from the n region into the p region
  • prevents the movement of electron from the p region into the n region
  • prevents the movement of holes from the n region into the p region
  • prevents the movement of holes from the p region into the n region
A transistor is working in common emitter mode. Its amplification factor $$\left( \beta  \right) $$ is $$80$$. If the base current is $$250\mu A$$, the collector current will be
  • $$\dfrac { 250 }{ 80 } \mu A$$
  • $$430\mu A$$
  • $$250\times 80\mu A$$
  • $$1.25\mu A$$
During the formation of $$p-n$$ junction, 
  • holes diffuse from $$p-$$side to $$n-$$side ($$p \rightarrow n$$)
  • electrons diffuse from $$p-$$side to $$n-$$side ($$p \rightarrow n$$)
  • electrons diffuse from $$n-$$side to $$p-$$side ($$n \rightarrow p$$)
  • holes diffuse from $$n-$$side to $$p-$$side ($$n \rightarrow p$$)
For creating a $$p-n$$ junction, 
  • we take one slab of p-type semiconductor and physically join it to another n-type semiconductor
  • continuous contact at the atomic level is necessary.
  • two macroscopic smooth flat slabs can be used
  • None of these
Due to the concentration gradient across p-, and n- sides, the motion of charge carries gives rise to_______ current across the junction
  • drift
  • diffusion
  • both diffusion and drift
  • None of these
When an external voltage ($$V$$) is applied across the diode in reverse bias with a barrier potential of $$V_o$$, the effect barrier height under reverse bias is 
  • $$V_o + V$$
  • $$V_o - V$$
  • $$V - V_o$$
  • None of these
When an external voltage $$V$$ is applied across a semiconductor diode such that $$p-$$side is connected to the positive terminal of the battery and $$n-$$side to the negative terminal, it is said to be
  • reverse biased.
  • forward biased.
  • bias free.
  • None of these
By adding certain impurities to                   in the appropriate concentrations the conductivity can be well-controlled.
  • semiconductors
  • conductors
  • insulators
  • superconductors
Which of the following statement(s) is/are true?
  • A hole is an electric charge carrier with a positive charge, equal in magnitude but opposite in polarity to the charge on the electron
  • A hole is the absence of an electron in a particular place in an atom
  • A hole is an electric charge carrier with a negative charge
  • none of these
In the figure, the numbers 1, 2, 3 represent barrier potential ($$V_o$$) of a p-n junction under forward bias
581240.JPG
  • 1 - high voltage battery 2 - without battery 3 - low voltage bettery
  • 1 - high voltage battery, 2 - low voltage battery, 3 - without battery
  • 1 - without battery, 2 - low voltage battery, 3 - high voltage battery
  • 1 - low voltage battery 2 - without battery 3 - high voltage bettery
In this $$I-V$$ characteristic curve of a zener diode, regions 1 and 2 respectively indicate
581269_043600d625cf4a168c62d6206a8778e6.png
  • forward bias and reverse bias regions.
  • reverse bias and forward bias regions.
  • forward bias regions only.
  • reverse bias regions only.
 The direction of the applied voltage ($$V$$) is opposite to the built-in potential $$V_o$$ .  The effective barrier height under forward bias is
  • ($$V_o + V$$).
  • ($$V_o V$$).
  • ($$V V_o$$).
  • ($$V_o \times V$$).
Which of the following is an example of an indirect band gap intrinsic semiconductor?
  • Silicon
  • Germanium
  • Gallium Arsenide
  • None of these
The diagram of a logic circuit is given below, the output of the circuit is represented by
596115_8b0c0c56768743bb8afb4927b87e3ed6.png
  • W+(X+Y)
  • W+(X.Y)
  • W.(X+Y)
  • W.(X.Y)
In the circuit below, $$A$$ and $$B$$ represent two inputs and $$C$$ represents the output.
The circuit represents 
596340_cc1b5d47149348108f38df36183b4308.PNG
  • $$\text{NOR gate}$$
  • $$\text{AND gate}$$
  • $$ gate$$
  • $$\text{OR gate}$$
Which of the following gates corresponds to the truth table given below?
596344.png
  • XOR
  • OR
  • NAND
  • NOR
In the following circuit, the output Y for all possible inputs A and B is expressed by the truth table
596139.jpg
The following circuit is equivalent to 
596187.jpg
  • AND gate
  • NOR gate
  • OR gate
  • NAND gate
A sinusoidal voltage of r.m.s. value of $$200 V$$ is connected to the junction diode and a capacitor C in the circuit shown so that half wave rectification occurs. The final potential difference across C in volts is
597209_996b09ad59b04cb791cd6f3a1f0a8124.png
  • $$213$$
  • $$170$$
  • $$283$$
  • $$352$$
In a half-wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be
  • 10 Hz
  • 25 Hz
  • 50 Hz
  • 100 Hz
0:0:1


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