NCERT Solutions for class 12 Physics | Chapter 14 - Semiconductor Electronics

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Questions
1 In semi conductor which are responsible for conduction:
A only electron
B electron and hole both
C only hole
D None of these

Answer:electron and hole both
2 In the middle of the depletion layer of a reverse biased p-n junction, the:
A electric field is zero
B potential is maximum
C electric field is maximum
D potential zero.

Answer:potential zero.
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3 p-n junction diode can be used as:
A amplifier
B oscillator
C detector
D modulator

Answer:detector
4 For germanium crystal, the forbidden energy gap in joules
A 1.216 × 10-19
B 1.76 × 10-19
C 1.6 × 10-19
D zero

Answer:1.216 × 10-19
5 In reverse biasing:
A large amount of current flows
B no current flows
C potential barrier across junction increases
D depletion layer resistance increases

Answer:potential barrier across junction increases
6 With fall of temperature, the forbidden energy gap of a semiconductor
A increases
B decreases
C sometimes increases and sometimes decreases
D remains unchanged

Answer:remains unchanged
7 Main function of a transistor is to :
A rectify
B simplify
C amplify
D all the above

Answer:amplify
8 In a common base amplifier the phase difference between the input signal voltage and output voltage is :
A π/2
B 0
C π/4
D π

Answer:0
9 On heating, resistance of semiconductors:
A decreases
B increases
C remains same
D first increases then decreases

Answer:decreases
10 On applying reverse bias to a junction diode, it:
A lowers the potential barrier
B raise the potential barrier
C increases the majority carrier current
D increases the minority carrier current

Answer:raise the potential barrier
11 In a p-type semiconductor, current conduction is by:
A atoms
B holes
C electrons
D protons

Answer:holes
12 Energy bands in solids are a consequence of:
A Ohm’s Law
B Pauli’s exclusion principle
C Bohr’s theory
D Heisenberg’s uncertainty principle

Answer:Pauli’s exclusion principle
13 To obtain p-type silicon semiconductor, we need to dope pure silicon with:
A aluminium
B phosphorus
C oxygen
D germanium

Answer:aluminium
14 The relation between number of free electrons (n) in a semiconductor and temperature (T) is given by:
A n ∝ T
B n ∝ T²
C n ∝ T1/2
D n ∝ T3/2

Answer:n ∝ T3/2
15 Number of electrons in the valence shell of a semiconductor is:
A 1
B 2
C 3
D 4

Answer:4
16 The material most commonly used to manufacture electronic solid state devices is :
A copper
B silicon
C germanium
D aluminium

Answer:silicon
17 Crystal diode is:
A amplifying device
B fluctuating device
C non-linear device
D linear device

Answer:non-linear device
18 Winch of the following gate is not an universal gate?
A OR
B NOT
C AND
D NAND

Answer:NAND
19 In intrinsic semiconductor at room temperature, the number of electrons and holes are:
A equal
B unequal
C infinite
D zero

Answer:equal.
20 In binary system III represents:
A 1
B 3
C 7
D 100

Answer:7

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