Question

Class 12 Physics MCQ Questions of Semiconductor Electronics: Materials, Devices and Simple Circuits with Answers?

Answer 1

The important MCQ Questions for Class 12 Physics are prepared after analyzing the syllabus and the previous year’s questions thoroughly. Students must start their preparation with Semiconductor Class 12 MCQ Questions available on the Sarthaks eConnect for easy reference.

The important Class 12 Physics MCQ Questions of Semiconductor Electronics: Materials, Devices, and Simple Circuits with Answers provide a deep insight into one of the important chapters. It helps to understand the Exam Pattern and Questions asked in the exams. Refer to the Class 12 Physics MCQ Questions of Semiconductor Electronics: Materials, Devices and Simple Circuits with Answers here along with a detailed clarification.

Practice MCQ Question for Class 12 Physics chapter-wise

1. Bonds in a semiconductor :

(a) trivalent
(b) covalent
(c) bivalent
(d) monovalent

2. Number of electrons in the valence shell of a semiconductor is:

(a) 1
(b) 2
(c) 3
(d) 4

3. In a p-type semiconductor, current conduction is by:

(a) atoms
(b) holes
(c) electrons
(d) protons

4. Main function of a transistor is to :

(a) rectify
(b) simplify
(c) amplify
(d) all the above

5. To obtain p-type silicon semiconductor, we need to dope pure silicon with:

(a) aluminium
(b) phosphorus
(c) oxygen
(d)germanium

6. 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

7. In a common base amplifier the phase difference between the input signal voltage and output voltage is :

(a) \(\frac{\pi}{2}\)
(b) 0
(c) \(\frac{\pi}{4}\)
(d) \(\pi\)

8. 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

9. On heating, resistance of semiconductors:

(a) decreases
(b) increases
(c) remains same
(d) first increases then decreases

10. In intrinsic semiconductor at room temperature, the number of electrons and holes are:

(a) equal
(b) unequal
(c) infinite
(d) zero

11. Winch of the following gate is not an universal gate?

(a) OR
(b) NOT
(c) AND
(d) NAND

12. Crystal diode is:

(a) amplifying device
(b) fluctuating device
(c) non-linear device
(d) linear device

13. The part of a transistor which is heavily doped to produce a large number of majority carriers is :

(a) base
(b) emitter
(c) collector
(d) None of these

14. The material most commonly used to manufacture electronic solid state devices is :

(a) copper
(b) silicon
(c) germanium
(d) aluminium

15. What is the number of possible crystal systems?

(a) 5
(b) 7
(c) 14
(d) 16

16. When npn transistor is used as an amplifier

(a) electrons move from collector to base
(b) holes move from emitter to base
(c) electrons move from base to collector
(d) holes move from base to emitter

17. For a common base amplifier, the values of resistance gain and voltage gain are 3000 and 2800 respectively. The current gain will be

(a) 1.1
(b) 0.98
(c) 0.93
(d) 0.83

18. The solids which have the negative temperature coefficient of resistance are:

(a) insulators only
(b) semiconductors only
(c) insulators and semiconductors
(d) metals

19. 

The correct Boolean operation represented by the circuit diagram drawn is :

(a) NOR
(b) AND
(c) OR
(d) NAND

20. The device that can act as a complete electronic circuit is

(a) Junction diode
(b) Integrated circuit
(c) Junction transistor
(d) Zener diode

21. The increase in the width of the depletion region in a p-n junction diode is due to :

(a) reverse bias only
(b) both forward bias and reverse bias
(c) increase in forwarding current
(d) forward bias only

22. The most commonly used material for making transistor is

(a) Copper
(b) Silicon
(c) Ebonite
(d) Silver

23. In a crystal, the atoms are located at the position of

(a) Maximum potential energy
(b) Minimum potential energy
(c) Zero potential energy
(d) Infinite potential energy

24. To obtain a P-type Si semiconductor, we need to dope pure Si with 

(a) Aluminium
(b) Phosphorous
(c) Oxygen  
(d) Germanium

25. To obtain a P-type germanium semiconductor, it must be doped with

(a) Arsenic
(b) Antimony
(c) Indium
(d) Phosphorus

Answer 2

1.  Answer : (b) covalent

Explanation: The electrons surrounding each atom in a semiconductor are part of a covalent bond. A covalent bond consists of two atoms "sharing" a pair of electrons. Each atom forms 4 covalent bonds with the 4 surrounding atoms. Therefore, between each atom and its 4 surrounding atoms, 8 electrons are being shared.

2. Answer : (d) 4

Explanation: Most conductors have just one electron in the valence shell. Semiconductors, on the other hand, typically have four electrons in their valence shell.

3. Answer : (b) holes

Explanation: In a p-type semiconductor, the electrical conduction is due to the presence of majority charge carriers (holes) and minority charge carriers (electrons).

4. Answer : (c) amplify

Explanation: Transistor, semiconductor device for amplifying, controlling, and generating electrical signals. Transistors are the active components of integrated circuits, or “microchips,” which often contain billions of these minuscule devices etched into their shiny surfaces.

5. Answer : (a) aluminium

Explanation: To obtain a P-type Si semiconductor, we need to dope pure Si with. Aluminium is trivalent impurity.

6. Answer : (a) electric field is zero

Explanation: When a n junction is reverse biased, the width of the depletion layer becomes large and so the electric field (\(E=\frac{v}{d}\)) becomes very small, nearly zero.

7. Answer : (b) 0

Explanation: As we know that in a common base amplifier the input signal is amplified but remains in phase with the output signal. From this statement, we get to know that the difference of output voltage and input voltage will be equal to zero.

8. Answer : (b) Pauli’s exclusion principle

Explanation: According to Pauli's exclusion principle, two electrons cannot have the same quantum numbers in a given molecule. Therefore, when two identical atoms combine to give rise to a diatomic molecule, each atomic orbital breaks up into two different molecular orbitals( different energy).

9. Answer : (a) decreases

Explanation: When a pure semiconductor is heated, its resistance decreases. When the temperature is raised, some covalent bonds in the semiconductor break due to the thermal energy supplied. Hence, the resistance decreases with the rise in temperature.

10. Answer : (a) equal

Explanation: At room temperature, in an intrinsic semiconductor the number of electrons in the conduction band is equal to the number of holes in valence band.

11. Answer : (d) NAND

Explanation: NAND and NOR gate are used as universal gate.

12. Answer : (c) non-linear device

Explanation: A crystal diode is a non- linear device. It doesn't Obey's ohms law.

13. Answer : (b) emitter

Explanation: The part of a transistor which is heavily doped to produce a large number of majority carriers, is. Emitter is heavily dopped.

14. Answer : (b) silicon

Explanation: Silicon (Si) is the most widely used material in semiconductor devices. Its combination of low raw material cost, relatively simple processing, and a useful temperature range makes it currently the best compromise among the various competing materials.

15. Answer : (b) 7

Explanation: In total there are seven crystal systems: triclinic, monoclinic, orthorhombic, tetragonal, trigonal, hexagonal, and cubic. A crystal family is determined by lattices and point groups.

16. Answer : (d) holes move from base to emitter

Explanation: For a npn transistor to be used as an amplifier, forward bias has to be applied on the transistor. Thus, when an npn transistor is used as an amplifier, holes move from base to emitter.

17. Answer : (c) 0.93

Explanation: For amplifiers:

Voltage gain = (Current gain) \(\times\) (Resistance gain)

Current gain = Voltage gain / Resistance gain

Hence , 

Current gain  = \(\frac{2800}{3000}\)

 = 0.93

18. Answer : (c) insulators and semiconductors

Explanation: For metals temperature coefficient of resistance is positive while for insulators and semiconductors, temperature coefficient of resistance is negative.

19. Answer : (d) NAND

Explanation: From the given logic circuit LED will glow, when voltage across LED is high.

A	B	Y
0	0	1
0	1	1
1	0	1
1	1	0

20. Answer : (b) Integrated circuit

Explanation: Integrated circuits are miniature electronic circuits produced within a single crystal of semiconductors such as silicon. They contain a million or so transistors and resistors or capacitors. They are widely used in memory circuits, microcomputers, pocket calculators and electronic watches on account of their low cost and bulk, reliability into specific regions of the semiconductor crystals.

21. Answer : (a) reverse bias only

Explanation: In reverse bias, external battery attracts majority charge carriers .So, width of the depletion region increase.

22. Answer : (b) Silicon

Explanation: Most transistors are made from very pure silicon, and some from germanium, but certain other semiconductor materials are sometimes used.

23. Answer : (b) Minimum potential energy

Explanation: In a crystal, atoms are located at the position of minimum potential energy.

24. Answer : (a) Aluminium

Explanation: Aluminium is a trivalent impurity. Trivalent impurity atoms have 3 valence electrons. Such atoms on being added to pure semiconductor, instead of producing free electrons, accept electrons from the semiconductor. For this reason, trivalent impurity atoms are called acceptor impurity atoms. The semiconductor so produced is called p-   type extrinsic semiconductor.

25. Answer : (c) Indium

Explanation: In p type germanium semiconductor, it must be doped with a trivalent impurity atom. Since indium is a third group member, therefore germanium must be doped in indium.

Click here to practice  MCQ Question for Semiconductor Electronics: Materials, Devices and Simple Circuit Class 12