CBSE Questions for Class 12 Engineering Physics Semiconductor Electronics: Materials,Devices And Simple Circuits Quiz 1 - MCQExams.com

In a $$p$$-type semi-conductor, the majority carriers are
  • Protons
  • Electrons
  • Holes
  • Positive ions
The Fermi level of an intrinsic semiconductor is pinned at the centre of the band gap. The probability of occupation of the highest electron state in valence band at room temperature, will be
  • Zero
  • Between zero and half
  • Half
  • One
The logic circuit shown in figure has the input wavefrom A and B as shown pick out from figure
1260126_49277d3023d949d8b10cbe1e3ff4bedd.png
  • None of these
Figure shows the particle realization of a logic gate. Identify the logic gate
1232158_eb30740a72f64cab9dc1af8ef84d5933.png
  • NAND
  • NOR
  • XOR
  • XNOR
The adjoining logic symbol is equivalent to
1228877_9be4d65482bd43c2b3c5a1cac7bff406.PNG
  • $$OR$$ gate
  • $$AND$$ gate
  • $$NOT$$ gate
  • $$NAND$$ gate
A reverse-biased diode is
What is the order of the reverse saturation current before breakdown in a Zener diode
  • ampere
  • milli-ampere
  • it depends on the applied voltage
  • micro-ampere
Write down the boolean expression for output $$Y$$ of system in figure
1234198_294715ca0f9d413abcb158044a514398.png
  • $$A \overset {-}{B} +\overset {-}{A} B$$
  • $$(\overset {-}{A}+ \overset {-}{B})(A+B)$$
  • $$ \overset {-}{A} \overset {-}{B} + AB$$
  • $$ AB + (\overset {-}{A}+ \overset {-}{B})$$
If output in a logic gate is low for either output to be high
  • AND gate
  • OR gate
  • NOR gate
  • NAND gate.
In the given circuit the current through the zener diode is. 
1264766_292ea0814e874f2889ca46bf023db119.png
  • 10 m A
  • 6.67 m A
  • 5 mA
  • 3.33 mA
The output of OR gate is 1 :-
  • If either one or both inputs are 1
  • Only if both inputs are 1
  • If either input is zero
  • If both inputs are zero
Identify the logic gate in figure.

16549.png
  • NAND
  • NOR
  • NOT
  • AND
What is the output $$Y$$ in the following circuit, when all the three inputs $$A,B,C$$ are first $$0$$ and then $$1$$?
1287441_68eeafe162824655b5980f22062c2614.PNG
  • $$0,1$$
  • $$0,0$$
  • $$1,0$$
  • $$1,1$$
The Boolean expression for NOR gate is:
  • $$\overline { A.B } =Y$$
  • $$A+B=Y$$
  • $$A.B=Y$$
  • $$\overline { A+B } =Y$$
Logic gate realised from pn junctions shown in figure is
1268821_e4d3b631510c4ef7bc3bf95f3096163e.png
  • OR gate
  • AND gate
  • NOT gate
  • NOR gate
Any digital circuit can be realised by repetitive use of only
  • NOT gates
  • OR gates
  • NAND gates
  • NOR gates
If a,b,c,d are input to a gate and x is its ouput, then as per the following time graph, the gate is 
1293813_afdfd4f8b90141f0919896dfc8529541.png
  • NAND
  • NOT
  • AND
  • OR
In the combination of the given gates the output $$Y$$ can be written in terms of inputs $$A$$ and $$B$$ as:
1276598_e171e63e5d974819bab5e02f80dfa7dc.PNG
  • $$\overline { A.B } $$
  • $$A.\overline { B } +\overline { A } .B$$
  • $$\overline { A.B } +A.B$$
  • $$\overline { A+B } $$
The following transistor circuit is equivalent to which logic gate ?
1290963_4b6d85b9dc3d45eb8de487b79fbb9a8e.PNG
  • OR
  • NAND
  • XOR
  • AND
In a forward biased $$P-N$$ junction carrying a certain amount of current, which of the following statement is false?
  • The depletion region width decrease in comparison to unbaised case
  • The electric field strength varies in depletion region
  • The neutral regions behave like ohmic reisters with small resistance.
  • The charge density in the depletion region is uniform.

The following logic gate circuit is equivalent to


1304143_0acf08b6689841d4b430d812628387d1.png
  • NAND gate
  • OR gate
  • XOR gate
  • NOT gate
A p-n junction diode connected in series with a resistor of 200 $$\Omega $$ is forward biased so that a current 200 mA flows.If the voltage across this combination is instantaneously reversed at t=0, the current through diode is approximately,
  • 400 mA
  • 200 mA
  • 100 mA
  • 0 mA
To get an output of $$1$$ from the circuit shown in figure the input must be:
1321052_beec1182f137407db5d9bb4115f94814.PNG
  • $$a=0,b=1,c=0$$
  • $$a=1,b=0,c=0$$
  • $$a=1,b=0,c=1$$
  • $$a=0,b=0,c=1$$
The combination of gates shown in the circuit is equivalent to
1428667_4580f230b498402ea9966fe4b6425ecc.png
  • OR
  • AND
  • NAND
  • NOR
In the following figure, the diodes which are forward biased are :
68615.PNG
  • (a), (b) and (d)
  • (c) only
  • (c) and (a)
  • (b) and (d)
In a PN junction : -
  • High potential at N side and low potential at P side
  • High potential at P side and low potential at N side
  • P and N both are at same potential
  • Undetermined
In a semiconductor diode, the depletion region is removed when:
  • the diode is in its forward conducting state
  • the diode is in its reverse non-conducting state
  • there is no potential difference between the anode and cathode
  • None of these
Zener diode is a voltage regulation device.
  • True
  • False
In the Boolean algebra :  $$\bar{A} . \bar{B}=$$ ......
  • $$\overline{A+B}$$
  • $$A.B$$
  • $$\overline{\bar A + \bar B}$$
  • $$A + B$$
When an input signal $$1$$ is applied to a NOT gate, its output is
  • $$1$$
  • $$0$$
  • either $$0$$ or $$1$$
  • both $$0$$ and $$1$$
In the given circuit the current through Zener Diode is close to : 
1332292_dda72ab576e441fb9ad3c3d4b5fd5570.PNG
  • $$6.0m\ A$$
  • $$4.0 m\ A$$
  • $$6.7\ mA$$
  • $$0.0\ mA$$
The truth table given in figure represents:
474479.jpg
  • AND - Gate
  • NOR - Gate
  • NAND - Gate
  • OR - Gate
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 maximum power of dissipation rating of $$1 W$$. The minimum voltage range of the DC source in the circuit is
  • $$0-24 V$$
  • $$0-5 V$$
  • $$0-12 V$$
  • $$0-8 V$$
Identify the gate and match A, B, Y in bracket to check.
99971.jpg
  • NOT $$(A=1, B=1, Y=1)$$
  • AND $$(A=1, B=1, Y=1)$$
  • OR $$(A=1, B=1, Y=0)$$
  • XOR $$(A=0, B=0, Y=0)$$
The combination of gates shown below yields 
40638.jpg
  • OR gate
  • NOT gate
  • XOR gate
  • NAND gate

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:

472818.png
  • NOT
  • AND
  • OR
  • NAND
To get an output offrom the circuit shown in figure the input must be 

474870.JPG
  • $$a=0, b=0, c=1$$
  • $$a=1, b=0, c=0$$
  • $$a=1, b=0, c=1$$
  • $$a=0, b=1, c=0$$
Carbon, silicon and germanium have four valence electrons each. At room temperature which one ofthe following statements is most appropriate ?
  • The number of free conduction electrons is significant in C but small in Si and Ge
  • The number of free conduction electrons is negligibly small in all the three
  • The number of free electrons for conduction is significant in all the three
  • The number of free electrons for conduction is significant only in Si and Ge but small in C
In the given circuit, the current through zener diode is:
868369_5382bc9c062d4daba6f533fb5cb78800.png
  • $$2.5\ mA$$
  • $$3.3\ mA$$
  • $$5.5\ mA$$
  • $$6.7\ mA$$
Given : A and B are input terminals.
Logic $$1= > 5V$$
Logic $$0= < 1V$$
Which logic gate operation, the following circuit does?
100303.jpg
  • AND Gate
  • OR Gate
  • XOR Gate
  • NOR Gate
In an unbiased n-p junction electrons diffuse from n-region to p- region because
  • electrons travel across the junction due to potential difference.
  • electrons concentration in n region is more as compared to that in p-region.
  • holes in p-region attract them.
  • only electrons move from n- to p- region and not the vice-versa.
What is the output Y in the following circuit when all the three inputs A, B, C are first $$0$$ and then $$1$$?

516334.png
  • $$1,1$$
  • $$0,1$$
  • $$0,0$$
  • $$1,0$$
Two following figure shows a logic gate circuit with two inputs A and B and the output Y. The voltage wave forms of A, B and Y are as given.
The logic gate is

306008.png
  • NOR gate
  • OR gate
  • AND gate
  • NAND gate
To get output $$1$$ for the following circuit, the correct choice for the input is.
477312.png
  • A$$=0$$, B$$=1$$, C$$=0$$
  • A$$=1$$, B$$=0$$, C$$=0$$
  • A$$=1$$, B$$=1$$, C$$=0$$
  • A$$=1$$, B$$=0$$, C$$=1$$
The increase in the width of the depletion region in a p-n junction diode is due to :
  • reverse bias only
  • both forward bias and reverse bias
  • increase in forward current
  • forward bias only
The output (X) of the logic circuit shown in the figure will be

308365.png
  • $$X=\bar{\bar{A}}.\bar{\bar{B}}$$
  • $$X=\overline{A.B}$$
  • $$X=A.B$$
  • $$X=\overline{A+B}$$

Which logic gate is represented by the following combination of logic gates?

333334.png
  • AND
  • NOR
  • OR
  • NAND
A Zener diode, having breakdown voltage equal to $$15\ V$$, is used in a voltage regulator circuit shown in figure. The current through the diode is
306837.png
  • $$10\ mA$$
  • $$15\ mA$$
  • $$20\ mA$$
  • $$5\ mA$$
The given electrical network is equivalent to:
638415_54ec4f124598430cb9e6e4dfb806ed51.png
  • NOT gate
  • AND gate
  • OR gate
  • NOR gate
When the input of a two input logic gate are 0 and 0, the output isWhen the inputs are 1 and 0, the output is zero. The type of logic gate is
  • XOR
  • NAND
  • NOR
  • OR
0:0:1


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