Semiconductor Devices PYQs Set 8 (PDF)

Set 8 of 17 · Questions 211-240 of 501

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Mere Teacher · Previous Year Questions JEE Main Physics · Semiconductor Devices · Set 8 (Q211-240)
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211. $The energy gap in case of which of the following is less than 3 eV ?$ (1) $Aluminium$ (2) $Iron$ (3) $Germanium$ (4) $Copper$ 212. $C and Si both have same lattice structure, having 4 bonding electrons in each. However, C is insulator whereas Si is intrinsic semiconductor. This is because [2012]$ (1) $The four bonding electrons in the case of C lie in the third orbit, whereas for Si they lie in the fourth orbit$ (2) $In case of C the valance band is not completely filled at absolute zero temperature$ (3) $In case of C the conduction band is partly filled even at absolute zero temperature$ (4) $The four bonding electrons in the case of C lie in the second orbit, whereas in the case of Si they lie in the third orbit$ 213. $For a transistor in CE mode to be used as an amplifier, it must be operated in :$ (1) $Both cut-off and Saturation$ (2) $Saturation region only$ (3) $Cut-off region only$ (4) $The active region only$ 214. $Consider an amplifier circuit in which a transistor is used in common-emitter mode. The load resistance 3 kΩ . When a signal of 30 mV is added to base emitter voltage, the base current is changed by 30 μA and the collector current is changed by 3 mA . The power gain in this circuit will be$ (1) $10000$ (2) $20000$ (3) $30000$ (4) $40000$ 215. $Minority carriers in a p -type semiconductor are$ (1) $free electrons$ (2) $holes$ (3) $neither holes nor free electrons$ (4) $both holes and free electrons.$ 216. $In a common emitter (CE) amplifier having a voltage gain G, the transistor used has transconductance 0.03 mho and current gain 25. If the above transistor is replaced with another one with transconductance 0.02 mho and cu1Tent gain 20, the voltage gain will be [2013]$ (1) $\frac{2}{3} G$ (2) $1.5 G$ (3) $\frac{1}{3} G$ (4) $\frac{5}{4} G$ 217. $The acceptor level of a p-type semiconductor is 6 eV . The maximum wavelength of light which can create a hole would be : Given hc = 1242 eVnm .$ (1) $414 nm$ (2) $103.5 nm$ (3) $207 nm$ (4) $407 nm$ 218. $Given below are two statements : Statement I : PN junction diodes can be used to function as transistor, simply by connecting two diodes, back to back, which acts as the base terminal. Statement II : In the study of transistor, the amplification factor β indicates ratio of the collector current to the base current In the light of the above statements, choose the correct answer from the options given below.$ (1) $Statement I is false but Statement II is true.$ (2) $Both Statement I and Statement II are true.$ (3) $Statement I is true but Statement II is false.$ (4) $Both Statement I and Statement II are false.$ 219. $If a semiconductor photodiode can detect a photon with a maximum wavelength of 400nm, then its band gap energy is Planck's constant h = 6.63 \times 10^{- 34}, J . s . Speed of light c = 3 \times 10^{8} m / s$ (1) $1.1 eV$ (2) $2.0eV$ (3) $3.1eV$ (4) $1.5eV$ 220. $A person applies a sine wave and square wave to an AND gate as shown in the figure (i) and (ii). Assuming that both the voltages are applied in phase, the person observes the output at E and F on (i) and (ii), respectively. [Assume minimum voltage of 5 V is equivalent to logic (i)] Sine wave, 50 Hz, 2 V . Sine wave, 100 Hz, 8 V Square wave, 107 Hz, 6 V Sine wave, 100 Hz, 8 V$ (1) $Square wave at 50 Hz and square wave at 100 Hz .$ (2) $Sine wave at 50 Hz and square wave at 100 Hz .$ (3) $No output and sine wave at 100 Hz .$ (4) $No output and pulsed wave at 100 Hz .$ 221. $For the logic circuit shown, the truth table is [NEET 2020]$ (1) $A B C 001011101111$ (2) $A B C 001011101110$ (3) $A B C 001010100110$ (4) $A B C 000010100111$ 222. $For the given circuit shown in fig, to act as full wave rectifier, a.c. input should be connected across ........and........the d.c. output would appear across........and........$ (1) $(A), (C) and (B), (D)$ (2) $(B), (D) and (A), (C)$ (3) $(A), (B) and (C), (D)$ (4) $(C), (A) and (D), (B)$ 223. $Which logic gate is represented by the following combination of logic gates?$ (1) $AND$ (2) $OR$ (3) $NOR$ (4) $NAND$ 224. $The logic operation performed by the following circuit is$ (1) $NOR$ (2) $AND$ (3) $NAND$ (4) $OR$ 225. $For the given digital circuit, write the truth table and identify the logic gate it represents$ (1) $NAND gate$ (2) $OR gate$ (3) $AND gate$ (4) $NOR gate$ 226. $Ge and Si diodes start conducting at 0.3 V and 0.7 V respectively. In the following figure if Ge diode connection are reversed, the value of V_{0} changes by: (assume that the Ge diode has large breakdown voltage)$ (1) $0.8 V$ (2) $0.6 V$ (3) $0.2 V$ (4) $0.4 V$ 227. $In the circuit, the logical value of A = 1 or B = 1 when potential at A or B is 5V and the logical value of A = 0 or B = 0 when potential at A or B is 0 V. The truth table of the given circuit will be :$ (1) $A 0101 B 0011 Y 0001$ (2) $A 0101 B 0011 Y 0111$ (3) $A 0101 B 0011 Y 0000$ (4) $A 0101 B 0011 Y 1110$ 228. $Identify the correct Logic Gate for the following output (Y) of two inputs A and B.$ (1) (2) (3) (4) 229. $In the figure, given that V_{BB} supply can vary from 0 to 5.0 V, V_{CC} = 5 V, β_{dc} = 200, R_{B} = 100 kΩ, R_{C} = 1 kΩ and V_{BE} = 1.0 V . The minimum base current and the input voltage at which the transistor will go to saturation, will be, respectively :$ (1) $25 μ A and 2.8 V$ (2) $20 μ A and 3.5 V$ (3) $20 μ A and 2.8 V$ (4) $25 μ A and 3.5 V$ 230. $The given circuit has two ideal diodes connected as shown in the figure. The current flowing through the resistance R_{1} will be [NEET 2016]$ (1) $2.5 A$ (2) $10.0 A$ (3) $1.43 A$ (4) $3.13 A$ 231. $For the following logic circuit, the truth table is [NEET 2023]$ (1) $A B Y 000101111$ (2) $A B Y 001010101110$ (3) $A B Y 000010100111$ (4) $A B y 001011101110$ 232. $The circuit has two oppositely connected ideal diodes in parallel. What is the current flowing in the circuit?$ (1) $2.31 A$ (2) $1.33 A$ (3) $1.71 A$ (4) $2.00 A$ 233. $For the logic circuit shown, the output waveform at Y is$ (1) (2) (3) (4) 234. $In semiconductors at a room temperature [2004]$ (1) $The valence band is partially empty and the conduction band is partially filled$ (2) $The valence band is completely filled and the conduction band is pa1tially filled$ (3) $The valence band is completely filled$ (4) $The conduction band is completely empty$ 235. $Following diagram performs the logic function of [2003]$ (1) $XOR gate$ (2) $AND gate$ (3) $NAND gate$ (4) $OR gate$ 236. $The output characteristics of a transistor is shown in the figure. When V_{CE} is 10V and I_{C} = 4.0mA, then value of β_{ac}, is_________$ 237. $A potential barrier of 0.4 V exists across a p-n junction. An electron enters the junction from the n-side with a speed of 6.0 x 105 m s^{- 1} . The speed with which electron enters the p side will be \frac{x}{3} \times 1 0^{5} m s^{- 1} the value of x is_______. (Given mass of electron = 9 x 10-31kg, charge on electron = 1.6 x 10-19C.)$ 238. $Two ideal diodes are connected in the network as shown in figure. The equivalent resistance between A and B is______Ω .$ 239. $Both the diodes used in the circuit shown are assumed to be ideal and have negligible resistance when these are forward biased. built in potential in each diode is 0.7V. For the input voltages shown in the figure, the voltage (in volts) at point A is .$ 240. $For the forward biased diode characteristics shown in the figure, the dynamic resistance at I_{D} = 3mA will be _____Ω$