CBSE Class 12 Physics – MCQ and Online Tests – Unit 14 – Semiconductor Electronics: Materials, Devices and Simple Circuits
Every year CBSE conducts board exams for 12th standard. These exams are very competitive to all the students. So our website provides online tests for all the 12th subjects. These tests are also very effective and useful for those who preparing for competitive exams like NEET, JEE, CA etc. It can boost their preparation level and confidence level by attempting these chapter wise online tests.
These online tests are based on latest CBSE Class 12 syllabus. While attempting these our students can identify the weak lessons and continuously practice those lessons for attaining high marks. It also helps to revise the NCERT textbooks thoroughly.
CBSE Class 12 Physics – MCQ and Online Tests – Unit 14 – Semiconductor Electronics: Materials, Devices and Simple Circuits
Question 1.
Main function of a transistor is to :
(a) rectify
(b) simplify
(c) amplify
(d) all the above
Answer
Answer: (c) amplify
Question 2.
To obtain p-type silicon semiconductor, we need to dope pure silicon with:
(a) aluminium
(b) phosphorus
(c) oxygen
(d)germanium
Answer
Answer: (a) aluminium
Question 3.
In intrinsic semiconductor at room temperature, the number of electrons and holes are:
(a) equal
(b) unequal
(c) infinite
(d) zero
Answer
Answer: (a) equal
Question 4.
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
Answer: (b) raise the potential barrier
Question 5.
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
Answer: (d) remains unchanged
Question 6.
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
Answer: (a) 1.216 × 10-19
Question 7.
Number of electrons in the valence shell of a semiconductor is:
(a) 1
(b) 2
(c) 3
(d) 4
Answer
Answer: (d) 4
Question 8.
To obtain electrons as majority charge carriers in a semiconductors the impurity mixed is:
(a) monovalent
(b) divalent
(c) trivalent
(d) pentavalent
Answer
Answer: (b) divalent
Question 9.
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
Answer: (d) potential zero.
Question 10.
Bonds in a semiconductor :
(a) trivalent
(b) covalent
(c) bivalent
(d) monovalent
Answer
Answer: (b) covalent
Question 11.
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
Answer: (b) 0
Question 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
Answer: (b) Pauli’s exclusion principle
Question 13.
Semiconductors of both p-type and n-type are produced by:
(a) ionic solids
(b) covalent solids
(c) metallic solids
(d) molecular solids
Answer
Answer: (b) covalent solids
Question 14.
In semi conductor which are responsible for conduction:
(a) only electron
(b) electron and hole both
(c) only hole
(d) None of these
Answer
Answer: (b) electron and hole both
Question 15.
In a p-type semiconductor, current conduction is by:
(a) atoms
(b) holes
(c) electrons
(d) protons
Answer
Answer: (b) holes
Question 16.
In binary system III represents:
(a) 1
(b) 3
(c) 7
(d) 100
Answer
Answer: (c) 7
Question 17.
On heating, resistance of semiconductors:
(a) decreases
(b) increases
(c) remains same
(d) first increases then decreases
Answer
Answer: (a) decreases
Question 18.
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
Answer: (d) n ∝ T3/2
Question 19.
p-n junction diode can be used as:
(a) amplifier
(b) oscillator
(c) detector
(d) modulator
Answer
Answer: (c) detector
Question 20.
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
Answer: (c) potential barrier across junction increases
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