Semiconductor Devices PYQs Set 3 (PDF)

Set 3 of 16 · Questions 61-90 of 467

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Mere Teacher · Previous Year Questions NEET Physics · Semiconductor Devices · Set 3 (Q61-90)
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61. $The correct relation between α (ratio of collector current to emitter current) and β (ratio of collector current to base current) of a transistor is:$ (1) $β = \frac{α}{1 + α}$ (2) $α = \frac{β}{1 - α}$ (3) $β = \frac{1}{1 - α}$ (4) $α = \frac{β}{1 + β}$ 62. $Choose the correct circuit which can achieve the bridge balance. [NEET 2024]$ (1) (2) (3) (4) 63. $Choose the correct statement about Zener diode:$ (1) $It works as a voltage regulator in reverse bias and behaves like simple p-n junction diode in forward bias.$ (2) $It works as a voltage regulator in both forward and reverse bias.$ (3) $It works a voltage regulator only in forward bias.$ (4) $It works as a voltage regulator in forward bias and behaves like simple p-n junction diode in reverse bias.$ 64. $The load resistance and the base-emitter voltage of a transistor in CE configuration are 5 kΩ and 0.02 V respectively. If the collector current is 2 mA, then its voltage gain is$ (1) $1000$ (2) $500$ (3) $1500$ (4) $50$ 65. $If the frequency of the input voltage is 50 Hz, applied to a (a) half wave rectifier and (b) full wave rectifier. The output frequency in both cases is respectively$ (1) $50 Hz, 50 Hz$ (2) $100 Hz, 100 Hz$ (3) $50 Hz, 100 Hz$ (4) $100 Hz, 50 Hz$ 66. $A semiconductorhas equal electron and hole concentration of 2 \times 10^{8} m^{- 3} . On doping with a certain impurity, the electron concentration increases to 4 \times 10^{10} m^{- 3}, then the new hole concentration of the semiconductor is$ (1) $10^{6} m^{- 3}$ (2) $10^{8} m^{- 3}$ (3) $10^{10} m^{- 3}$ (4) $10^{12} m^{- 3}$ 67. $A p‐n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV It can detect a signal of wavelength [2009]$ (1) $6000 A$ (2) $4000 nm$ (3) $6000 nm$ (4) $4000 A$ 68. $A p-n junction diode is reverse biased with a voltage of 8 V . If the resistance of the diode is 4 \times 10^{7} Ω, then the reverse saturation current is$ (1) $32 μA$ (2) $2 μA$ (3) $0.2 μA$ (4) $0.5 μA$ 69. $The part of a transistor which is most heavily doped to produce large number of majority charge carries is :$ (1) $emitter$ (2) $base$ (3) $collector$ (4) $can be any of the above three$ 70. $In the three parts of a transistor, 'Emitter' is of$ (1) $moderate size and heavily doped$ (2) $large size and lightly doped$ (3) $thin size and heavily doped$ (4) $large size and moderately doped$ 71. $The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the :$ (1) $crystal structure$ (2) $variation of the number of charge carries with temperature$ (3) $type of bonding$ (4) $variation of scattering mechanism with temperature$ 72. $The width of the depletion region in a P - N junction diode is$ (1) $increased by reverse bias$ (2) $increased by forward bias$ (3) $decreased by reverse bias$ (4) $Independent of the bias voltage$ 73. $Sodium has body centred packing. Distance between two nearest atoms is 3.7 A. The lattice parameter is [2009]$ (1) $6.8 A$ (2) $4.3 A$ (3) $3.0 A$ (4) $8.6 A$ 74. $If α -current gain of a transistor is 0.98 . What is the value of β -current gain of the transistor?$ (1) $4.9$ (2) $0.49$ (3) $5$ (4) $49$ 75. $The resistivity of a material is found to be 10^{8} Ω - m . Then the material would be$ (1) $Only insulator$ (2) $Only metal$ (3) $Only semiconductor$ (4) $Only superconductor$ 76. $In a full wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be :$ (1) $50 Hz$ (2) $25 Hz$ (3) $100 Hz$ (4) $70.7 Hz$ 77. $A npn transistor is connected in common emitter configuration in a given amplifier. A load resistance of 800Ω is connected in the collector circuit and the voltage drop across it is 0.8 V. If the current amplification factor is 0.96 and the input resistance of the circuit is 192Ω, the voltage gain and the power gain of the amplifier will respectively be: [2016]$ (1) $4, 3.84$ (2) $3.69, 3.84$ (3) $4, 4$ (4) $4, 3.69$ 78. $If the temperature of the semi-conductor is increased, which of the following is correct statement?$ (1) $It's resistance increases.$ (2) $The number of electrons in valence band increases.$ (3) $The number of electrons in conduction band increases.$ (4) $The number of holes in valence band decreases.$ 79. $When p-n junction diode is forward biased, then-$ (1) $the depletion region is reduced and barrier height is increased.$ (2) $the depletion region is widened and barrier height is reduced.$ (3) $both the depletion region and barrier height are reduced.$ (4) $both the depletion region and barrier height are increased.$ 80. $The curve between charge density ρ and distance r near a p-n junction is best represented by$ (1) (2) (3) (4) 81. $In a CE transistor amplifier, the audio signal voltage across the collector resistance of 2 kΩ is 2 V. If the base resistance is 1 kΩ and the current amplification of the transistor is 100, the input signal voltage is [2012]$ (1) $10 mV$ (2) $0.1 V$ (3) $1.0 V$ (4) $1 mV$ 82. $The density of an electron-hole pair in a pure germanium is 3 \times 10^{16} m^{- 3} at room temperature. On doping with aluminium, the hole density increases to 4.5 \times 10^{22} m^{- 3} . Now the electron density (in m^{- 3}) in doped germanium will be$ (1) $1 \times 10^{10}$ (2) $2 \times 10^{10}$ (3) $0.5 \times 10^{10}$ (4) $4 \times 10^{10}$ 83. $The device that can act as a complete electronic circuit is [2010]$ (1) $Junction diode$ (2) $Integrated circuit$ (3) $Junction transistor$ (4) $Zener diode$ 84. $In forward biasing of the p‐n junction [2011]$ (1) $the positive terminal of the battery is connected to n ‐side and the depletion region becomes thin$ (2) $the positive terminal of the battery is connected to n ‐side and the depletion region becomes thick$ (3) $the positive terminal of the battery is connected to p ‐side and the depletion region become thin$ (4) $the positive terminal of the battery is connected to p ‐side and the depletion region becomes thick$ 85. $The material used in the fabrication of infrared LED's is$ (1) $silicon$ (2) $germanium$ (3) $gallium arsenide phospide$ (4) $carbon dioxide$ 86. $An NPN transistor is used in common emitter configuration as an amplifier with 1kΩ load resistance. Signal voltage of 10 mV is applied across the base-emitter. The produces a 3 mA change in the collector current and 15μA change in the base current of the amplifier. The input resistance and voltage gain are$ (1) $0.33 kΩ, 1.5$ (2) $0.67 kΩ, 300$ (3) $0.67 kΩ, 200$ (4) $0.33 kΩ, 300$ 87. $A transistor is connected in common emitter configuration. The collector supply is 8 V and the voltage drop across a resistance of 800Ω in the collector circuit is 0.5 V . If the current gain factor α is 0.96 , then the base current is$ (1) $2.6 \times 10^{- 5} A$ (2) $3.6 \times 10^{- 5} A$ (3) $5.6 \times 10^{- 5} A$ (4) $6.6 \times 10^{- 5} A$ 88. $A 0 K temperature, a p ‐type semiconductor [2002]$ (1) $has few holes and few free electrons$ (2) $has equal numbers of holes and free electrons$ (3) $has few holes but no free electrons$ (4) $does not have any charge carrier$ 89. $In a p -type semiconductor the donor level is at 50 meV above the valence band. To produce one electron, the maximum wavelength of light photon required is (Planck's constant, h = 6.6 \times 10^{- 34} Js and speed of light in vacuum, c = 3 \times 10^{8} ms^{- 1})$ (1) $0.0248 mm$ (2) $0.248 mm$ (3) $2.48 mm$ (4) $24.8 mm$ 90. $The output of an OR gate is connected to both the inputs of a NAND gate. The combination will serve as a :$ (1) $NOT gate$ (2) $NOR gate$ (3) $AND gate$ (4) $OR gate$