CBSE Questions for Class 12 Engineering Physics Semiconductor Electronics: Materials,Devices And Simple Circuits Quiz 2 - MCQExams.com

The following one represents logic addition is 
  • $$1 + 1 = 2$$
  • $$1 + 1 = 10$$
  • $$1 + 1 = 1$$
  • $$1 + 1 = 11$$
The logic gate represented in given figure is
468086.PNG
  • OR Gate
  • NOT Gate
  • NAND Gate
  • XOR Gate
In the given circuit, the voltage across the voltage across the load is maintained at 12V. The current in the zener diode varies from 0-50 mA. What is the maximum watage of the diode?

469172.jpg
  • 12 W
  • 6 W
  • 0.6 W
  • 1.2 W
The circuit as shown in figure, the equivalent gate is

469127.png
  • NOR gate
  • OR gate
  • AND gate
  • NAND gate
Which of the following contains a covalent bond?
  • $$copper$$
  • $$NaCl$$
  • $$germanium$$
  • $$helium$$
The bond, that exists in a semiconductor is
  • covalent bond
  • ionic bond
  • metalic bond
  • hydrogen bond
A hole is
  • a positively charged electron.
  • an electron in the valence band.
  • an unfilled covalent bond.
  • an excess electron in covalent bond.
The mobility of free electrons is greater than that of free holes because 
  • they carry negative charge
  • they are light
  • their mutual collisions are less
  • they require low energy to continue their motion
In a metal, the separation between conduction band and valence band is of the order
  • $$100\ eV$$
  • $$10\ eV$$
  • $$0\ eV$$
  • $$1\ eV$$
The value indicated by Fermi energy level in an intrinsic semiconductor is
  • the average energy of electrons and holes.
  • the energy of electrons in conduction band.
  • the energy of holes in valence band.
  • the energy of forbidden region.
There is no hole current in conductors, because they have
  • high conductivity
  • high electron density
  • no valence band
  • overlapping of valence and conduction bands
Forbidden gap in a pure conductor is
  • $$0\ eV$$
  • $$0.7\ eV$$
  • $$1.1\ eV$$
  • $$6\ eV$$
The conduction band and valency band of a good conductor are
  • well separated.
  • just touch.
  • very close.
  • overlapped.
Which of the following are correct for insulators?
  • The valence band is partially filled with electrons.
  • The conduction band is partially filled with electrons.
  • The conduction band is partially filled with electrons and valence band is empty.
  • The conduction band is empty and the valence band is filled with electrons.
p-n junction diode acts as
  • ohmic resistance
  • non-ohmic resistance
  • both A and B
  • amplifier
When the conductivity of a semiconductor is only due to breaking of covalent bonds, the semiconductor is called
  • n-type
  • p-type
  • intrinsic
  • extrinsic
The main cause of avalanche breakdown is
  • ionisation by collision.
  • high doping.
  • recombination of electrons and holes.
  • low doping.
The main cause of Zener breakdown is
  • the base semiconductor being germanium.
  • production of electron-hole pairs due to thermal excitation.
  • low doping.
  • high doping.
In semiconductors, at a room temperature
  • the valence band is partially empty and the conduction band is partially filled.
  • the valence band is completely filled and the conduction band is partially filled.
  • the valence band is completely filled.
  • the conduction band is completely empty.
In an intrinsic semiconductor, conductivity is
  • low at room temperature
  • average
  • high at room temperature
  • zero at room temperature
In an intrinsic semiconductor, the Fermi energy level is
  • nearer to valence band than conduction band.
  • equidistant from conduction band and valence band.
  • nearer to conduction band than valence band.
  • bisecting the conduction band.
The current flow in a Zener diode is mainly due to
  • thermally generated charge carriers
  • minority charge carriers
  • collision generated charge carriers
  • ions
A Zener diode
  • is a lightly doped junction diode.
  • heavily doped junction diode.
  • is either p-type or n-type.
  • has no p-n junction.
In an intrinsic semiconductor, conductivity is due to
  • doping
  • breaking of covalent bonds
  • free electrons
  • holes
p-n junction diode can be used as
  • amplifer
  • detector
  • oscillator
  • capacitor
Among the following which one gives output $$1$$ in the AND gate.
  • $$A = 0,\ B = 0$$
  • $$A = 1,\ B = 1$$
  • $$A = 1,\ B = 0$$
  • $$A = 0,\ B = 1$$
The avalanche breakdown in p-n junction is due to
  • shift of Fermi level.
  • cumulative effect of conduction band electron.
  • widening of forbidden gap.
  • high impurity concentration.
In positive logic, the logic state $$1$$ corresponds to
  • positive voltage
  • zero voltage
  • lower voltage level
  • higher voltage level
In the Boolean algebra, the following one is wrong
  • $$1 + 0 = 1$$
  • $$0 + 1 = 1$$
  • $$1 + 1 = 1$$
  • $$0 + 0 = 1$$
In Boolean algebra, $$A + B = Y$$ implies that 
  • sum of $$A$$ and $$B$$ is $$Y$$.
  • $$Y$$ exists when $$A$$ exists or $$B$$ exists or both $$A$$ and $$B$$ exist.
  • $$Y$$ exists only when $$A$$ and $$B$$ both exist.
  • $$Y$$ exists when $$A$$ or $$B$$ exist but not when both $$A$$ and $$B$$ exist.
If ‘p’ region of a semi conductor is connected to negative and ‘n’ region to positive pole, it is said to be
  • directed biased
  • unbiased
  • forward biased
  • reverse biased
Which of the following is not the function of a NOT gate?
  • Stop a signal.
  • Invert an input signal.
  • Complement a signal.
  • Change the logic in a digital circuit.
The energy band gap is maximum in
  • metals
  • super conductors
  • insulators
  • semiconductors
Among the following one can act as the building blocks for the other gates is
  • NAND and NOR
  • NAND and AND
  • XOR and OR
  • NOT and OR
An AND gate is followed by a NOT gate in series. With two inputs $$A$$ & $$B$$, the Boolean expression for the out put $$Y$$ will be :
  • $$A.B$$
  • $$A + B$$
  • $$\overline{A+B}$$
  • $$\overline{A.B}$$
The gate that has only one input terminal
  • NOT
  • NOR
  • NAN
  • XOR
The value of $$A.\bar{A}$$ in Boolean algebra is
  • $$0$$
  • $$1$$
  • $$A$$
  • $$\bar{A}$$
In Boolean algebra $$A.B = Y$$ implies that :
  • product of $$A$$ and $$B$$ is $$Y$$
  • $$Y$$ exists when $$A$$ exists or $$B$$ exists
  • $$Y$$ exists when both $$A$$ and $$B$$ exist but not when only $$A$$ or $$B$$ exists
  • $$Y$$ exists when $$A$$ or $$B$$ exists but not both $$A$$ and $$B$$ exist.
The output of a 2-input OR gate is zero only when its
  • both inputs are $$0$$.
  • either input is $$1$$.
  • both inputs are $$1$$.
  • either input is $$0$$.
The value of $$\bar{A} + A$$ in the Boolean algebra is
  • $$A$$
  • $$\bar{A}$$
  • $$0$$
  • $$1$$
NOR gate is the series combination of
  • NOT gate followed by OR gate.
  • OR gate followed by NOT gate.
  • AND gate followed by OR gate.
  • OR gate followed by AND gate.
The following truth table is for :
ABY
110
101
011
001
  • NAND gate
  • AND gate
  • XOR gate
  • NOT gate
The truth table for NOT gate is
If $$A = B = 1$$, then in terms of Boolean algebra the value of $$A.B + A$$ is not equal to
  • $$B.A+B$$
  • $$B+A$$
  • $$B$$
  • $$\bar{A}.B$$
The logic expression which is NOT true in Boolean algebra is
  • $$[\bar{1}+\bar{1}].1=0$$
  • $$[\bar{1}+0].1=0$$
  • $$[\bar{1}+0].\bar{1}=0$$
  • $$[1+1].1=0$$
The symbol represents

16081.png
  • NOT gate
  • OR gate
  • AND gate
  • NOR gate
In the Boolean algebra, of the following one which is not equal to $$A$$ is
  • $$A.A$$
  • $$A + A$$
  • $$\bar{A}.A$$
  • $$\overline{\bar A + \bar A}$$
In the Boolean algebra : $$A + B =$$
  • $$\bar{A}$$+$$\bar{B}$$
  • A.B
  • $$\bar{\bar{A}}+\bar{\bar{B}}$$
  • $$\bar{\bar{A}}$$+$$\bar{B}$$
If $$A = 1$$ and $$B = 0$$, then in terms of Boolean algebra the value of $$A.A + B$$ is
  • $$A$$
  • $$B^2$$
  • $$B$$
  • $$A \cdot B$$
If $$A = 1, B = 0$$ then the value of $$\bar {A} + B $$ in terms of Boolean algebra is
  • $$A$$
  • $$B$$
  • $$B + A$$
  • $$A.\bar{B}$$
0:0:1


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