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CBSE Questions for Class 12 Engineering Physics Semiconductor Electronics: Materials,Devices And Simple Circuits Quiz 5 - MCQExams.com

The load voltage is approximately constant when a zener diode is
  • Forward-biased
  • Reverse-biased
  • Operating in the breakdown region
  • Unbiased
What is the order of magnitude of the resistance of a dry human body?
  • 10Ω
  • 104Ω
  • 10 MΩ
  • 10μΩ
 If the series resistance decreases in an unloaded zener regulator, the zener current
  • Decreases
  • Stays the same
  • Increases
  • Equals the voltage divided by the resistance
For detecting the light_______________.
  • The photodiode has to be forward biased
  • The photodiode has to be reversed biased
  • The LED has to connected in forward bias mode
  • The LED has to be connected in reverse bias mode
A semi conductor device with both active and passive electronic elements diffused into a silicon water to form a functional circuit is called.
  • Thin-film circuit
  • Integrated circuit
  • Hybrid-circuit
  • Thick-film circuit
The n-side of the depletion layer of a p-n junction.
  • Always has same width as of the p-side
  • Has no bound charges
  • Is negatively charged
  • Is positively charged
Which of the following gates will have an output of 1?
696207_8f2c35b5f75d4197970fc914e5ef25cf.jpg
  • D
  • A
  • B
  • C
The breakdown in a reverse biased p-n junction diode is more likely to occur due to.
  • large velocity of the minority charge if the doping concentration is small.
  • large velocity of the minority charge carriers if the doping concentration is small.
  • strong electric field in a depletion region if the doping concentration is small.
  • strong electric filed in the deplention region if the doping conentration is large.
Which of the following devices can be used as a square law device for modulation.
  • p-n-p transistor in active region
  • p-n junction diode near threshold voltage.
  • Superconductor
  • Inductor
The logic symbols shown here are logically equivalent to :-
1132108_0a2c9807d82a46dfaf4bdfc7c1078a43.PNG
  • AND and OR gate
  • NOR and NAND gate
  • OR and AND gate
  • NAND and NOR gate
Zener breakdown takes place if:
  • Doped impurity is low
  • Doped impurity is high
  • Less impurity in N-part
  • Less impurity in P-type
On increasing the temperature of a semi-conductor material
  • Density of charge-carrier as well as their mobilities both increases
  • Density of charge-carriers increases, but their mobilities decreases
  • Density of charge-carries decreases, but their mobilities increases
  • Both density of charge-carriers as well as their mobilities decreases
Conventional flow of current will always be from -
  • p typen type
  • n type p type
  • n Type n type
  • None of these
When a p-n junction diode is connected in forward bias its barrier potential
  • decreases and less current flows in the circuit
  • decreases and more current flows in the circuit
  • increases and more current flows in the circuit
  • decreases and no current flows in the circuit
The process by which ac is converted into dc is known as
  • Purification
  • Amplification
  • Rectification
  • Current Amplification
Semi-conductor are formed if the bonds are
  • van der Walls
  • ionic
  • metallic
  • covalent
The nature of binding for a crystal with alternate and evenly spaced positive and negative ions is:
  • metallic
  • covalent
  • dipolar
  • ionic
Consider the following statements A and B and identify the correct answer.
Statement(A):A Zener diode is always connected in reverse bias to use it as voltage.
Statement(B):The potential barrier of a p-n junction lies between 0.1 to 0.3 V, approximately.
  • A and B are correct.
  • A and B are wrong.
  • A is correct but B is wrong.
  • A is wrong but B is correct.
There is a sudden increase in current in zener diode is
  • Due to rupture of bonds
  • Resistance of deplection layer becomes less
  • Due to high doping
  • Due to less doping
A p-n junction diode cannot be used
  • as a rectifier.
  • for converting light energy to electric energy.
  • for getting light radiation.
  • for increasing the amplitude of an AC signal.
A Zener diode when used as a voltage regulator, is connected 
(a) in forward bias. 
(b) in reverse bias.
(c) in parallel to the load.
(d) in series to the load.
  • (a) and (b) are correct
  • (b) and (c) are correct
  • (a) only is correct
  • (d) only is correct
AND gate
  • it has no equivalence to switching circuit.
  • it is equivalent to series switching circuit.
  • it is equivalent to parallel switching circuit.
  • it is a mixture of series and parallel switching circuit.
In an insulator, the energy gap between conduction band and valence band is about
  • 0 eV
  • 6 eV
  • 1 eV
  • 0.6 eV
Consider the following statements A and B and identify the correct answer:
A) germanium is preferred over silicon in the construction of Zener diode.
B) germanium has high thermal stability than silicon in the construction of Zener diode.
  • Both (A) and (B) are true.
  • Both (A) and (B) are false.
  • (A) is true but (B) is false.
  • (A) is false but (B) is true.
The following is NOT equal to 0 in the Boolean algebra is
  • ¯¯A.0
  • A.ˉA
  • A.0
  • ¯A+¯A
Digital circuit can be made by repetitive use of :
  • OR gates
  • AND gates
  • NOT gates
  • NAND gates
NAND and NOR gates are called universal gates because they
  • are universally available.
  • can be combined to produce OR, AND and NOT gates.
  • are widely used in the integrated circuits.
  • can be easily manufactured.
In the Boolean algebra: ¯A+B is equal to:
  • A + B
  • ˉˉA+ˉˉB
  • ¯¯A.B
  • ˉA . ˉB
The minimum number of gates required to realise the expression Z=DABC+D¯ABC is
  • One
  • Two
  • Eight
  • Five
Boolean expression Y=A.ˉB+B.ˉA is given. If A=1,B=1 then Y=
  • 0
  • 1
  • 11
  • 10
The gate that can act as a building block for the digital circuits is 
  • OR
  • NOT
  • AND
  • NAND
A diode made of silicon has a barrier potential of 0.7 V and a current of 20 mA passes through the diode when a battery of emf 3 V and a resistor is connected to it. The power dissipated across the resistor and diode are
  • 0.046 W, 0.014 W
  • 4.6 W, 0.14 W
  • 0.46 W, 0.14 W
  • 46 W, 14 W
The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than 2480 nm is incident on it. The forbidden band energy for the semiconductor in eV is 
  • 0.5
  • 0.9
  • 0.7
  • 1.1
Consider a two-input AND gate of figure below. Out of the four entries for the Truth Table given here, the correct ones are
16531.JPG
  • All
  • 1 and 2 only
  • 1, 2 and 3 only
  • 1, 3 and 4 only
From the adjacent circuit, the output voltage is

16496_c49a484e27ff43fca70f3349e69ed794.png
  • 10V
  • 100V
  • 90V
  • zero
The logic expression which is not equal to 1 in Boolean algebra is
  • A+1
  • A.ˉA
  • A+ˉA
  • ¯¯A+A
From the circuit shown below, the maximum and minimum value of zener diode current are :
16497_1a95c39592dd46d4b12a686fc3d73d3f.png
  • 6 mA, 5 mA
  • 14 mA, 5 mA
  • 9 mA, 1 mA
  • 3 mA, 2 mA
Boolean expression for the gate circuit shown below is
16559.png
  • A+ˉA=1
  • A+1=1
  • A+A=A
  • A+0=A
In the given circuit, two input wave forms A and B are applied simultaneously. The resultant wave form at Y is
16563.png
Logic gate having an output of 1 is
To get an output Y=1 from the circuit above, the input must be

16535.png
  • A-0 B-1 C-0
  • A-1 B-0 C-0
  • A-1 B-0 C-1
  • A-1 B-1 C-0
The input of A and B for the Boolean expression (¯A+B).(¯A.B)=1 is 
  • 0,0
  • 0,1
  • 1,0
  • 1,1
The output Y of the gate circuit shown in the fig is

16546.png
  • ˉA+ˉB
  • ¯ˉA+ˉB
  • ¯A+B
  • A + B
The combinations of the NAND gates shown hereunder are equivalent to
16554.png
  • an OR gate and an AND gate respectively
  • an AND gate and a NOT gate respectively
  • an AND gate and OR gate respectively
  • an OR gate and an NOT gate respectively
Given above are four logic gate symbols. Those for OR, NOR and NAND are respectively
16552.jpg
  • a, d, c
  • d, a, b
  • a, c, d
  • d, b, a
A Truth table is given below. The logic gate having following truth table is
A    B   Y
0    0    1
1    0    0
0    1    0
1     1    0
  • NAND gate
  • NOR gate
  • AND gate
  • OR gate
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
16556.png
  • 0,0
  • 0,1
  • 1, 0
  • 1,1
The expression of Y in the above circuit is
16576.png
  • ABCD
  • A+BCD
  • A+B+C+D
  • AB+CD
In the given circuit, if A and B represent two inputs and C represents the output, the circuit represents
16609.png
  • NOR gate
  • AND gate
  • gate
  • OR gate
The output Y of the gate circuit shown in the figure below is 
16573.png
  • ¯A.B
  • ˉA.ˉB
  • ¯¯A+B
  • ˉA+ˉB
0:0:3


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