CBSE Questions for Class 12 Engineering Physics Semiconductor Electronics: Materials,Devices And Simple Circuits Quiz 15 - MCQExams.com

A NOR gate and a NAND gate are connected as shown in the figure. Two different sets of inputs are given to this setup. In the first case, the inputs to the gates are $$A=0,B=0,C=0$$. In the second case, the inputs are $$A=1,B=0,C=1$$. The output $$D$$ in the first case and second case respectively are:
470375.PNG
  • $$0$$ and $$0$$
  • $$0$$ and $$1$$
  • $$1$$ and $$0$$
  • $$1$$ and $$1$$
Identify the semiconductor devices whose characteristics are given above in the order $$(a), (b), (c), (d):$$

472859.png
  • Simple diode, Zener diode, Solar cell, Light dependent resistance
  • Zener diode, Simple diode, Light dependent resistance, Solar cell
  • Solar cell, Light dependent resistance, Zener diode, Simple diode
  • Zener diode, Solar cell, Simple diode, Light dependent resistance
What is the value of output voltage $$v _ { 0 }$$ in the circuit shown in the figure


1213757_6adaa68463ad448688bab6bbfdc5d446.jpg
  • 6V
  • 15V
  • 20V
  • 26V
A 5 V zener diode is used to regulate the voltage across load resistor $$R_L$$ and the input voltage varies in between 10 V to 15 V. The load current also varies from 5 mA to 50 mA. Find the value of series resistance R. 
Given, $$I_Z(min)=20 mA$$
  • $$70 \Omega$$
  • $$90.91 \Omega$$
  • $$142.86 \Omega$$
  • $$71.43 \Omega$$
A zener diode voltage regulator operated in the range $$120-180\  V$$ produces a constant supply of $$110\  V$$ and $$250\  mA$$ to the load. If the maximum current is to be equally shared between the load and zener, then the values of series resistance ($$\displaystyle { R }_{ S }$$) and load resistance ($$\displaystyle { R }_{ L }$$) are:
  • $$\displaystyle { R }_{ L }=70\ \Omega ;{ R }_{ S }=280\ \Omega $$
  • $$\displaystyle { R }_{ L }=440\ \Omega ;{ R }_{ S }=140\ \Omega $$
  • $$\displaystyle { R }_{ L }=140\ \Omega ;{ R }_{ S }=440\ \Omega $$
  • $$\displaystyle { R }_{ L }=280\ \Omega ;{ R }_{ S }=70\ \Omega $$
Find the minimum and maximum load currents for which the zener diode as shown in figure will maintain regulation. Given, $$V_Z=10 V, R_Z=0 \Omega,  R=450 \Omega, I_Z(min)=2 mA $$ and $$I_Z(max)=60 mA$$
507024_d790fb6f28014a63b68c4089de6c1afb.png
  • $$0 mA, 33.3 mA$$
  • $$31.3 mA, 0 mA$$
  • $$2 mA, 31.3 mA$$
  • $$31.3 mA, 31.3 mA$$
Consider an open-circuited p-n junction in thermal equilibrium. Let $$J_{p,drift}$$ and $$J_{p,diff}$$ be the hole drift and diffusion current densities, respectively, and let $$J_{n,drift}$$ and $$J_{n,diff}$$ be the corresponding electron current densities. Of the following equalities, mark false,at all points in the p-n junction structure.
  • $$J_{n,drift}$$ + $$J_{p,diff}$$ = -$$J_{n,diff} - J_{p,diff}$$
  • $$J_{n,drift}$$ + $$J_{n,diff}$$ = $$J_{p,drift} + J_{p,diff}$$
  • $$J_{n,drift}$$ = $$J_{n,diff}$$ and $$J_{p,drift} = J_{p,diff}$$
  • $$J_{n,drift}$$ + $$J_{p,diff}$$ = - $$J_{n,drift} - J_{p,diff}$$
In the circuit diagram given A and B are switches. The logic operation, which the switches can perform, is.....?
931543_1a85446909a64ac19cb3886fc6a4501d.JPG
  • NAND
  • OR
  • AND
  • None of these 
The waveforms A and B given below are given as input to a NAND gate. Then, its logic output $$y$$ is
674068_565e7ca1b61847f4970044dae10621f9.png
  • for $$t_1$$ to $$t_2 ; y=0$$
  • for $$t_2$$ to $$t_3 ; y=1$$
  • for $$t_3$$ to $$t_4 ; y=1$$
  • for $$t_4$$ to $$t_5 ; y=0$$
  • for $$t_5$$ to $$t_6 ; y=0$$
When a semiconductor is heated, its resistance.
  • Remains the same
  • Decreases
  • Increases
  • May increases or decreases depending on the semiconductor
Truth table for the given circuit will be

870163_6e9dd56d309d43908f0e2d3eafb10ed5.png
Two junction diodes one of germanium $$(Ge)$$ and other of silicon $$(Si)$$ are connected as shown in figure to a battery of emf $$12\ v$$ and a load resistance $$10\ k\ \Omega$$. The germanium diode conducts at $$0.3\ V$$ and silicon diode at $$0.7\ V$$. When a current flows in the circuit, then the potential of terminal $$Y$$ will be:
669281_d6a0b884a98c49fba620a49628080610.jpg
  • $$12\ V$$
  • $$11\ V$$
  • $$11.3\ V$$
  • $$11.7\ V$$
Mobilities of electrons and holes in a sample of intrinsic germanium at room temperature are $$0.36m^2V^{-1}s^{-1}$$ and $$0.17m^2V^{-1}s^{-1}$$. The electron and hole densities are each equal to $$2.5\times 10^{19}m^3$$. The electrical conductivity of germanium is
  • $$4.24Sm^{-1}$$
  • $$2.12Sm^{-1}$$
  • $$1.09Sm^{-1}$$
  • $$0.47Sm^{-1}$$
Which of the following is NOT true about a zener diode?
  • It is used as a voltage regulator.
  • It is forward biased.
  • It is reverse biased.
  • It has a breakdown voltage.
In a diode detector, output circuit consist of $$R=1M\Omega \quad and\quad C=1pF$$. Calculate the carrier frequency it can detect.
  • $$3 \times 10^ 6Hz$$
  • $$1 \times 10^ 6Hz$$
  • $$30 \times 10^ 6Hz$$
  • $$4 \times 10^ 6Hz$$
If the lattice constant of this semiconductor is decreased, then which of the following is correct?
1093384_57cc357ec37a4e12bdaba71e91ef7e75.png
  • All $$E_{c}, E_{g}, E_{v}$$ increase
  • $$ E_{c}$$ and $$ E_{v}$$ increases but $$ E_{g}$$ decrease
  • $$ E_{c}$$ and $$ E_{v}$$ decreases but $$ E_{g}$$ increase
  • All $$E_{c}, E_{g}, E_{v}$$ decrease
A semiconductor X is made by doping a germanium crystal with arsenic $$(Z=33)$$. A second semiconductor Y is made by doping germanium with indium$$(Z=49)$$. The two are joined end to end and connected to a battery as shown. Which of the following statements is correct?
1100743_f90489a23d704ad0bad662e45f40b088.png
  • X is P-type, Y is N-type and the junction is forward biased
  • X is N-type, Y is P-type and the junction is forward biased
  • X is P-type, Y is N-type and the junction is reverse biased
  • X is N-type, Y is P-type and the junction is reverse biased
The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than 2480nm is incident on it. The band gap(in eV) for the semiconductor is
  • 0.9
  • 0.7
  • 0.5
  • 0.1
There photo dlodes $$D_{1}, D_{2}$$ and $$D_{3}$$ are made of semiconductor having band gap $$2.5\ eV, 2\ eV$$ and $$3\ eV$$ respectively. Which one will be able to detect light of wavelength $$6000\ A^o$$?
  • $$D_{1}$$
  • $$D_{2}$$
  • $$D_{3}$$
  • $$D_{1}$$ and $$D_{2}$$ both
The following configuration of gate is equivalent to:
1027130_da35944491d048a8862723e8aefe82ec.png
  • $$NAND$$
  • $$XOR$$
  • $$OR$$
  • $$None\ of\ these$$
If the revers bias voltage applied  to a p-n junction diode is increased, its barrier capacitance would:
  • increase
  • decrease
  • remain constant
  • first increase then decrease
If no external voltage is applied across p-n junction, there would be 
  • no electric field across the junction
  • an electric field pointing from n-type side across the junction
  • an electric field pointing from p-type to n-type side across the juncrtion
  • none of these
The output of the gate is low when at least one of the its input is high. This is true for:-
  • NOR
  • OR
  • AND
  • NAND
In a zener regulated power supply of a zener diode with $$V_z$$ = 6V is used for regulation. The load current is to be 4 mA and the unregulated input is 10 V. The value of series resistor $$R_s$$ is
  • less than $$ 5 \ \Omega$$
  • Infinite
  • greater than 100 $$\Omega$$
  • zero
The length of germanium rod is $$0.928cm$$ and its area of cross-section is $$1\ mm^{2}$$. If for germanium $$n_1=2.5\times 10^{19}cm^{3}$$. $$\mu_{h}=0.19m^{2}V^{-1}s^{-1}$$. Its resistance is
  • $$2.5k\Omega$$
  • $$4.0k\Omega$$
  • $$5.0k\Omega$$
  • $$10.0k\Omega$$
In the figure shown, the maximum and minimum currents through Zener diode are
1182045_c3d67ef96b764685813857627a737cb0.GIF
  • 5 mA, 1 mA
  • 14 mA, 6 mA
  • 14 mA, 5 mA
  • 9 mA, 1 mA
The current density (J) for an intrinsic semiconductor is given by which of the following equations?
  • $$j=n_1 . e . (\mu_e+\mu_h) . E$$
  • $$j=n_1 . e . (\mu_e-\mu_h) . E$$
  • $$j=\dfrac{n_1 . e . (\mu_e-\mu_h)} {E}$$
  • $$j=\dfrac{E}{n_1 . e . (\mu_e+\mu_h)} $$
The following data are for intrinsic germanium at 300 K. $$n_1 = 2.4 \times 10^{19} \ /m^3, \ \mu_e = 0.39m^2 \ / Vs, \ \mu_n = 0.19 m^2 \ /Vs$$. Calculate the conductivity of intrinsic germanium.
  • $$4.3 Sm^{-1}$$
  • $$1.21 Sm^{-1}$$
  • $$2.22 Sm^{-1}$$
  • $$4.22 Sm^{-1}$$
For inputs (A, B) and output (Y) of the following gate can be expressed as 
1154030_97e18dd46fe74579adf2ddb7870ec580.png
  • $$A\oplus B$$
  • A.B
  • A+ B
  • $$\ \overset { - }{ A }B +\overset { - }{ B }A $$
A zener diode is specified as having a breakdown voltage of $$9.1 V$$, with a maximum power dissipation of $$364 \ mW$$. What is the maximum current the diode can handle? 
  • $$40 \ mA$$
  • $$60 \ mA$$
  • $$50 \ mA$$
  • $$45 \ mA$$
If the lattice constant of this semiconductor is decreased, then which of the following is correct?
1205545_d4dfc1133c824949ba7840d43cad20f4.PNG
  • All $$E_c, E_g, E_v$$ increase
  • $$E_c$$ and $$E_v$$ increase but $$E_g$$ decreases
  • $$E_c$$ and $$E_v$$ decrease but $$E_g$$ incerases
  • All $$E_c, E_g, E_v$$ decrease
Evaluate:
1193268_d9e11d377ed44abf95f1573762476d71.jpg
  • NAND
  • AND
  • NOR
  • OR
The majority current in a $$p-n$$ junction is $$:-$$  
  • from the $$n-$$ side to the $$p-$$ side
  • from the $$p-$$ side to the $$n-$$ side
  • from the $$n-$$ side to the $$p-$$ side if the junction is forward$$-$$biased and in the opposite direction if it is reverse biased
  • from the $$p-$$ side to the $$n-$$ side if the junction is forward$$-$$biased and in the opposite direction if it is reverse biased
The diode used in the circuit shown in the figure has a constant voltage drog currents and a maximum power rating of 100 mW. What should be the value r, connected in series with the diode, for obtaining maximum current l?
1223885_1d1ea05002c74cf391c68e3b4b2844c0.PNG
  • 200 $$\Omega $$
  • 6.67 $$\Omega $$
  • 5 $$\Omega $$
  • 1.5 $$\Omega $$
Silicon is a semiconductor. On adding a small quantity of arsenic to it its conductivity 
  • inceases
  • decreases
  • remaions the same
  • becomes zero
The output in the figure is:-

1216963_21e14e2a735741eeb89d7437c05ebabe.PNG
  • $$\overline {AB} $$
  • $$\overline {\overline A .\overline B } $$
  • $$\overline {\overline {A.B} } $$
  • $${\overline A .\overline B }$$
Two wires A and B of same material and same mass have radius $$2$$r and r. If resistance of wire A is $$34\Omega$$, then resistance of B will be?
  • $$544\Omega$$
  • $$272\Omega$$
  • $$68\Omega$$
  • $$17\Omega$$
If in  a p-n junction diode, a square input signal  of $$10 V$$ is applied as shown. Then, the output singnal across $$RL$$ will be :-  
1312438_9b656ba5e8e9410bb804ecddcf6ff709.PNG
C and Si both have a same lattice structure, having 4 bonding electrons in each. However, C is insulator whereas Si is intrinsic semiconductor:-
  • In case of C the valance bond is not completely filled at absolute zero temperature
  •  In the case of C, the conduction band is partly filled even at zero temperature
  • The four bonding electron in case of C lies in the second orbit whereas in case of Si lies in third orbit
  • The four bonding electron in case of C lies in third orbit whereas for Si they lie in fourth orbit
What is the output of the combination of the gates shown in fig. below ?
1322039_e2a065f6176f4917b8e7ada6195aab7b.png
  • $$A + \overline{A.B}$$
  • $$A + A. B$$
  • $$(A + B) . (\overline{A . B})$$
  • $$(A + B) (\overline{A + B})$$
If in a p-n junction diode, a square input signal of $$10V$$ is applied as shown. Then, the output signal across $${R}_{L}$$ will be-
1325003_3e7ea425b3cf497fb8f5d4ca83a20a7a.png
Shown in the figure is a combination of logic gates. The output values at $$P$$ and $$Q$$ are correctly represented by which of the following?
1324955_42c645995e54451d85be8b1fc4d08194.jpg
  • $$0,0$$
  • $$1,1$$
  • $$0,1$$
  • $$1,0$$
What is the output of the combination of the gates shown in fig. below ?
1322041_00fed9517bff49e4b595319496ce7e0b.png
  • $$A + \overline{A . B}$$
  • $$A + A. B$$
  • $$(A + B) . (\overline{A. B})$$
  • $$(A + B) (\overline{A + B})$$
What is the output of the combination of the gates shown in fig. below ?
1322040_0805fa8cf3614a72955c0bd237753b1d.png
  • $$A + \overline{A . B}$$
  • $$A + A. B$$
  • $$(A + B) . (\overline{A . B})$$
  • $$(A + B) (\overline{A + B})$$
In the adjacent diagram A and B represent two inputs and C represent the output,
The circuit represents
1317224_bcf3c417ce884432a0ed815bfce7e471.PNG
  • NOR gate
  • AND gate
  • NAND gate
  • OR gate
 In p - type semi conductor, there are 
  • immobile negative ions
  • immobile positive ions
  • no minority carriers
  • holes as majority carriers
The combined network of the following NOR gates will behaves as
1358001_521cb5ec8da44fc6bf075b68c9dd25ef.png
  • AND gate
  • XOR gate
  • NOR gate
  • NAND gate
The logic which produces LOW output when one of the input is HIGH and produces HIGH output only when all its inputs are LOW is called _.
  • AND gate
  • OR gate
  • NOR gate
  • NAND gate
For a diode connected in parallel with a resistor, which is the most likely current (I) -voltage (V) characteristics?
1337483_69c0ff142860481499ac11f2ad28f9be.PNG
In the resistance box, a double wired coil is fixed as shown in the figure so that :-
1360842_2343d0f75bb34fa7be7a58f8906dcdad.png
  • The wire may not be heated
  • The wire may not break easily
  • Electromagnetic induction may increase
  • Self induction in the coil may be negligible
0:0:1


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