Semiconductor Electronics Class 12 MCQ Questions: Before the transistor’s discovery in 1948, vacuum tubes were the primary tools for managing electron flow in electronic circuits. These tubes, including the vacuum diode, triode, tetrode, and pentode, controlled electrons using varying voltages between their electrodes in a vacuum to prevent energy loss due to collisions. This unidirectional flow earned them the name “valves.” Despite their functionality, vacuum tubes were bulky, power-intensive, and had limited reliability. In the 1930s, the foundation for modern semiconductor electronics was laid. Solid-state semiconductors could control charge flow through external influences like light or heat, unlike vacuum tubes where electrons came from heated cathodes. Semiconductor devices, operating within the solid material, required no external heating or large vacuums, making them compact, energy-efficient, and reliable. Even Cathode Ray Tubes (CRTs) are being replaced by solid-state Liquid Crystal Display (LCD) monitors, marking the shift away from vacuum tube principles. Early uses of natural galena crystals as radio wave detectors foreshadowed semiconductor potential.
In this chapter we are introduced to semiconductor physics and explore devices like junction diodes and bipolar junction transistors, along with practical applications in various circuits. Let us check the MCQs from this chapter to understand the chapter in the best possible way. This chapter is very important because it has a weightage of 7 marks.
Semiconductor Electronics: Materials, Devices and Simple Circuits Class 12 MCQ Questions with Answers
Also, check:
1 A p-type semiconductor is
(a) positively charged
(b) negatively charged
(c) uncharged
(d) uncharged at 0K but charged at higher temperatures
Answer: (c)
2 Number of electrons in the valence shell of a pure semiconductor is
(a) 1
(b) 2
(c) 3
(d) 4
Answer: (d)
3 In a half wave rectifier, the r.m.s. value of the a.c. component of the wave is
(a) equal to d.c. value
(b) more than d.c. value
(c) less than d.c. value
(d) zero
Answer: (b)
4 In semiconductors, at room temperature
(a) the conduction band is completely empty
(b) the valence band is partially empty and the conduction band is partially filled
(c) the valence band is completely filled and the conduction band is partially filled
(d) the valence band is completely filled
Answer: (b)
5 Barrier potential of a P-N junction diode does not depend on
(a) doping density
(b) diode design
(c) temperature
(d) forward bias
Answer: (b)
6 If the two ends of a p-n junction are joined by a wire
(a) there will not be a steady current in the circuit
(b) there will be a steady current from the n-side to the p side
(c) there will be a steady current from the p-side to the n side
(d) there may or may not be a current depending upon the resistance of the connecting wire
Answer: (a)
7 Forward biasing is that in which applied voltage
(a) increases potential barrier
(b) cancels the potential barrier
(c) is equal to 1.5 volt
(d) None of these
Answer: (b)
8 When p-n junction diode is forward biased then
(a) both the depletion region and barrier height are reduced
(b) the depletion region is widened and barrier height is reduced
(c) the depletion region is reduced and barrier height is increased
(d) Both the depletion region and barrier height are increased
Answer: (a)
9 Filter circuit
(a) eliminates a.c. component
(b) eliminates d.c. component
(c) does not eliminate a.c. component
(d) None of these
Answer: (a)
10 Bridge type rectifier uses
(a) four diodes
(b) six diodes
(c) two diodes
(d) one diode
Answer: (a)
11 What is the resistivity of a pure semiconductor at absolute zero ?
(a) Zero
(b) Infinity
(c) Same as that of conductors at room temperature
(d) Same as that of insulators at room temperature
Answer: (b)
Related:
