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MCQS
NCERT Class 12 MCQ Quiz Hub
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1. What is the number of possible crystal systems?
5
7
14
16
2. The material most commonly used to manufacture electronic solid state devices is :
copper
silicon
germanium
aluminium
3. A p-type semiconductor is:
negatively charged
positively charged
uncharged
None of the these
4. The part of a transistor which is heavily doped to produce a large number of majority carriers is :
base
emitter
collector
None of the these
5. Crystal diode is:
amplifying device
fluctuating device
non-linear device
linear device
6. Bonds in a semiconductor :
trivalent
covalent
bivalent
monovalent
7. Number of electrons in the valence shell of a semiconductor is:
1
2
3
4
8. Semiconductors of both p-type and n-type are produced by:
ionic solids
covalent solids
metallic solids
molecular solids
9. With fall of temperature, the forbidden energy gap of a semiconductor
increases
decreases
sometimes increases and sometimes decreases
remains unchanged
10. In a p-type semiconductor, current conduction is by:
atoms
holes
electrons
protons
11. The relation between number of free electrons (n) in a semiconductor and temperature (T) is given by:
n ∝ T
n ∝ T²
n ∝ T1/2
n ∝ T3/2
12. n reverse biasing:
large amount of current flows
no current flows
potential barrier across junction increases
depletion layer resistance increases
13. Main function of a transistor is to :
rectify
simplify
amplify
All the above
14. To obtain p-type silicon semiconductor, we need to dope pure silicon with:
aluminium
phosphorus
oxygen
germanium
15. On applying reverse bias to a junction diode, it:
lowers the potential barrier
raise the potential barrier
increases the majority carrier current
increases the minority carrier current
16. To obtain electrons as majority charge carriers in a semiconductors the impurity mixed is:
monovalent
divalent
trivalent
pentavalent
17. In the middle of the depletion layer of a reverse biased p-n junction, the:
electric field is zero
potential is maximum
electric field is maximum
potential zero.
18. In a common base amplifier the phase difference between the input signal voltage and output voltage is :
π/2
0
π/4
π
19. Energy bands in solids are a consequence of:
Ohm’s Law
Pauli’s exclusion principle
Bohr’s theory
Heisenberg’s uncertainty principle
20. In semi conductor which are responsible for conduction:
only electron
electron and hole both
only hole
None of the above
21. In binary system III represents:
1
3
7
100
22. On heating, resistance of semiconductors:
decreases
increases
remains same
first increases then decreases
23. p-n junction diode can be used as:
amplifier
oscillator
detector
modulator
24. In intrinsic semiconductor at room temperature, the number of electrons and holes are:
equal
unequal
infinite
zero
25. In full wave rectifier, input a.c. current has a frequency v. The output frequency of current is :
V/2
V
2V
None
26. Winch of the following gate is not an universal gate?
OR
NOT
AND
NAND
27. Zener diode is used for:
Zener diode is used for:
amplification
stabilisation
rectification
28. In semi conductor, at room temperature :
the valence bond is partially empty and the conduction band is partially filled
the valence bond is partially empty and the conduction band is partially filled
the valence band is completely filled
None of the above
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