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

The intrinsic charge carrier density in germanium crystal at $$ 300 K is 2.5 \times 10^{13} / cm^3 $$. density in an n-type germanium crystal at 300 K be $$ 5 \times 10^{16} /cm^3 $$,the hole density in this n-type crystal at 300 K would be 
  • $$ 2.5 \times 10^{13} / cm^3 $$
  • $$ 5 \times 10^6 / cm^3 $$
  • $$ 1.25 \times 10^{10} / cm^3 $$
  • $$ 0.2 \times 10^4 / cm^3 $$
The combination of gates shown below yields.
1288184_6cc4961d6820457397c1d86d42c1a7a3.png
  • NAND gate.
  • NOR gate.
  • XOR gate.
  • OR gate.
A wire of resistance 'R' is cut into four equal parts and they are bundled together side by side to form a thicker wire. The resistance of the bundle is
  • $$\cfrac{R}{16}$$
  • $$\cfrac{R}{2}$$
  • $$2R$$
  • $$4R$$
The input signals at NAND gate is given below
1286491_524048a76c3a4632a43bdb5db0a0862c.png
Which of the PN-junction is forward biased?
  • None of these
To get output $$'1'$$ and $$R$$, for the given logic gate circuit the input values must be
1330615_9bab795daadd40b2afaf90ba09d6a807.png
  • $$X = 0, Y = 1$$
  • $$X = 1, Y = 1$$
  • $$X = 0, Y = 0$$
  • $$X = 1, Y = 0$$
Energy bands in solids are a consequence of
  • Ohm's Law
  • Pauli's exclusion principle
  • Bohr's theory
  • Heisenberg's uncertainty principle
A PN-junction has a thickness of the order of :
  • $$1\, gm$$
  • $$1\, mm$$
  • $$1\, \mu m$$
  • $$1\, pm$$

The output of an AND gate is connected to both the inputs of a NOR gate, then this circuit will act as a 
  • OR gate
  • NOR gate
  • AND gate
  • NOT gate
  • NAND gate
In a P-N  junction, a potential barrier exists across the function. A hole with kinetic energy of 300 meV *approaches the junction Find the kinetic energy of the hole it crosses the junction it the hole approached  the Junction from the p-side and
  • 105 me V
  • 55 me V
  • 50 me V
  • 100 me V

In a p-type semiconductor, the acceptor level lies 
  • near the conduction band
  • half way between conduction and valence bands
  • within conduction band
  • near the valence band
In the following common emitter circuit if $$\beta = 100, V _ { C E } = 7 V , V _ { B E } = \text { negligible, } R _ { C } = 2 \mathrm { k } \Omega $$ then $$I _ { B }$$ is
1298793_4be923aa52c044499087b19925789f90.png
  • $$0.01 \mathrm { mA }$$
  • $$0.04 \mathrm { mA }$$
  • $$0.02 \mathrm { mA }$$
  • $$0.03 \mathrm { mA }$$
For the circuit show below, the current through the zener diode is :
1333998_3e3d4f1531db494f9b7eadd7552a16eb.PNG
  • 5 mA
  • Zero
  • 14 mA
  • 9 mA
Find the value of $${ V }_{ 0 }$$
1350502_81a6bdedc4e14fbb80921dc80902dbf3.png
  • 5.7 V
  • 5.3 V
  • 6 V
  • 5 V
When PN junction os forward biased , the current in junction 
  • increases
  • decreases
  • Remains same
  • None of these
With the rise of temperature, the specific resistance of semiconductor?
  • Increases
  • Remains unchanged
  • Decreases
  • None of these
Truth table for the following digital circuit will be:-
1324681_59aaac674ed3420097b0694015de1622.png
The figure shows two $$NAND$$ gates follow by a $$NOR$$ gate. The system is equivalent to the following logic gate
1350943_b6baa52d5709466da023f41b34b042c6.png
  • $$OR$$
  • $$AND$$
  • $$NAND$$
  • None of these
The output of the given logic circuit is:
1332828_70cf8133b2a546eba6057a38485920ac.PNG
  • $$\bar { A} B$$
  • $$A\bar { B} $$
  • $$AB+\bar {AB } $$
  • $$A\bar { B} +\bar { A} B$$
With the help of the arrangement shown in figure which of the following gates could be realised?
996147_dc93ca1e7d644f7e88a07c9dd25d8129.png
  • OR
  • NAND
  • AND
  • NOR
A Zener diode 
  • has negative temperature coefficient of resistance.
  • has sharp breakdown at low reverse voltage.
  • rectifies alternating voltage.
  • is operated only in forward bias.
Two conducting wires of same material and of equal lengths, resistance and resistivity having ratio $$1:2$$. Their diameter ratio will be 
  • $$1:2$$
  • $$1:4$$
  • $$4:1$$
  • $$1:\sqrt{2}$$
In a semiconductor
  • There are no free electrons at any temperature
  • The number of free electrons is more than in a conductor
  • There is no free electrons at OK
  • None of these
With  rise in temperature the electrical conductivity of intrinsic semiconductor:
  • increases
  • decreases
  • first increases and then decreases
  • first decreases and then increases
Wire $$P$$ and $$Q$$ have the same resistance at a ordinary room  temperature .When heated resistance  at a ordinary room temperature .When heated resistance of $$P$$ increases and that of $$Q$$ decreases. we conclude that
  • $$P$$ is semiconductor and $$Q$$ is conductor
  • $$P$$ is conductor and $$Q$$ is semiconductor
  • $$P$$ is n-type semiconductor and $$Q$$ is $$p-$$ type conductor
  • None of the above
The width of deplection layer in P-N junction diode is :
  • $$10^-3$$ m
  • $$10^-4$$ m
  • $$10^-5$$ m
  • $$10^-6$$ m

In a common emitter transistor the current gain isWhat is change in collector current, when change in base current is $$250\mu A$$
  • $$9 \times {10^{ - 2}}A$$
  • $$8 \times {10^{ - 6}}A$$
  • $$2 \times {10^{ - 2}}A$$
  • $$3 \times {10^{ - 7}}A$$
Symbolic representation of photodiode is
What n - type semiconductor is heated : 
  • number of electrons increases while that of holes decreases
  • number of holes increases while that of electrons decreases
  • number of electrons and holes increase equally.
  • number of electrons and holes increase equally
  • none of these
In the forward bias characteristic curve, a diode appears as :
  • an OFF switch
  • a high resistance
  • an ON switch
  • a capacitor
In a $$\mathrm { n }$$ -p-n transistor circuit, the collector current is $$10 \mathrm { mA }$$ . If $$95$$ percent of the electrons emitted reach the collector, which of the following statements are true?
  • The emitter current will be 8$$\mathrm { mA }$$
  • The base current will be $$2 \mathrm { mA }$$
  • The base current will be $$ 0.53\mathrm { mA }$$
  • None of these
Choose the correct option:
Electrical conductivity of a semi conductor-
  • decreases with rise in its temperature.
  • increases with rise in its temperature.
  • does not changes with temperature.
  • first decreases and then increases with rise in temperature.
Identity the gate in the figures
1547720_d1a9aeab81484cb3b45f7d6361a948f2.png
  • AND
  • NOR
  • XOR
  • NAND
The Boolean expression for NAND gate is -
  • $$Y = A + B$$
  • $$Y = A.B$$
  • $$Y = \overline {A + B}$$
  • $$Y = \overline {A. B}$$

The thickness of the P-N junction is m. 
  • $${10^{ - 2}}$$
  • $${10^{ - 6}}$$
  • $${10^{ - 8}}$$
  • $${10^{ - 12}}$$
Select and write the correct option from the options given in each question:
Optical Detector is:
  • Diode Laser
  • Laser
  • LED
  • Photo Diode
The arrangement of $$NAND$$ gates shown below effectively work as
1033108_9617069b479d4872a483b6438a3284ca.png
  • $$AND$$ gate
  • $$OR$$ gate
  • $$NAND$$ gate
  • $$NOR$$ gate
The circuit given is equivalent to
1524999_6136b97821ba411d9d05d6926cefe18d.png
  • OR gate
  • AND gate
  • NAND gate
  • NOR gate
Good resistance coils are made of ?
  • Copper
  • Manganin
  • Gold
  • Silver
The combination of NAND gates shown here under (figure) are equivalent to
1578488_3b62a2c6d874451b85fe95dd48264759.png
  • An OR gate and an AND gate respectively
  • An AND gate and a NOT gate respectively
  • An AND fate and an OR gate respectively
  • An OR gate and a NOT gate respectively.
Determine the current through zener diode for the circuit shown in figure is: (Given: zener diode break down voltage $$V_z=5.6V$$)
1611265_c9f30b27474b40969ebbd9793b2a16e0.png
  • $$7mA$$
  • $$17mA$$
  • $$10mA$$
  • $$15mA$$
For the following combination of gates, select the correct statement
1591421_fe1c08d2475944d48f1b95ce01a9717e.PNG
  • The output is $$1$$ when both the inputs are $$1$$
  • The output is $$0$$ when both the inputs are $$0$$
  • The output is $$0$$ when the two inputs differ
  • The outputs is $$1$$ when the two inputs differ
A device or power strip designed to protect electronic equipment from power surges and spikes is known as.....
  • Surge Suppressors
  • Ping
  • Gateway
  • None of these
Logic gate for inpute A an  B is given in figure .
Which table is correct for given gates system:
1613210_34cd2d4f63fe48969a31c9d9526e6b3e.png
LCD stands for ______________.
  • Low Crystal Display
  • Less Crystal Display
  • Liquid Crystal Display
  • All the above
The reverse breakdown voltage of a Zener diode is $$5.6\ V$$ in the given circuit.
The current $$I_{Z}$$ through the Zener is
1613806_5dbe563b9a0c460696a0f732c8724a9a.png
  • $$7\ mA$$
  • $$17\ mA$$
  • $$10\ mA$$
  • $$15\ mA$$
The truth table for the circuit given in the fig. is:
1614918_8374efa07d604e4eb406b1ef054a2fc0.png
  • $$\begin{vmatrix} A&B&Y \\0&0&1\\0&1&1\\1&0&0\\1&1&0 \end{vmatrix}$$
  • $$\begin{vmatrix} A&B&Y \\0&0&0\\0&1&0\\1&0&1\\1&1&1 \end{vmatrix}$$
  • $$\begin{vmatrix} A&B&Y \\0&0&1\\0&1&0\\1&0&0\\1&1&0 \end{vmatrix}$$
  • $$\begin{vmatrix} A&B&Y \\0&0&1\\0&1&1\\1&0&1\\1&1&1 \end{vmatrix}$$
For the given circuit shown in figure, the potential of the battery is varied from $$10V$$ to $$16V$$. If by zener diode breakdown voltage is $$6V$$, find maximum current through zener diode.
1613181_bc1b3375701a4e03b2a00c7cc8ff9f6f.png
  • $$1.5\ mA$$
  • $$3.5\ mA$$
  • $$5\ mA$$
  • $$6.5\ mA$$
The figure represents a voltage regulator circuit using a Zener diode. The breakdown voltage of the Zener diode is 6V and the load resistance is $$R_L = 4 k \Omega$$. The series resistance of the circuit is $$R_i = 1 k \Omega$$. If the battery voltage $$V_B$$ varies from $$8V$$ to $$16V$$, what are the minimum and maximum values of the current through Zener diode ? 

1614647_eaf001927ab6481e980e46d1b7f39003.png
  • $$0.5 \, mA ; \, 6 \, mA$$
  • $$0.5 \, mA ; \, 8.5 \, mA$$
  • $$1.5 \, mA ; \, 8.5 \, mA$$
  • $$1 \, mA ; \, 8.5 \, mA$$
Figure shown a DC voltage regulator circuit, with a Zener diode of breakdown voltage = $$6V$$. If the unregulated input voltage varies between $$10 V$$ to $$16 V$$, then what is the maximum Zener current ?
1615164_8407f4dc350745ceb96afe4d48cf04ee.png
  • $$2.5 \, mA$$
  • $$3.5 \, mA$$
  • $$7.5 \, mA$$
  • $$1.5 \, mA$$
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