NEET & JEE · Physics · Class 12Semiconductor Electronics Materials Devices and Simple Circuits — NEET Physics MCQs
30 questions written by hand against the NCERT chapter. Every wrong option is explained, not just the right one.
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Sample questions from this chapter
Which pair consists of elemental semiconductors commonly used in electronic devices?
- Silicon and germanium ✓
- Copper and aluminium
- Diamond and graphite
- Sodium chloride and mica
Answer: A. Silicon and germanium are group-IV elemental semiconductors whose conductivity can be controlled through temperature and doping.
Why not B: Copper and aluminium are metallic conductors with abundant mobile electrons rather than elemental semiconductors.
Why not C: These are carbon allotropes; diamond is insulating and graphite conducts by a different band structure.
Why not D: Sodium chloride and mica are ordinarily classified as insulators, not elemental semiconductor materials.
Carbon, silicon, and germanium have energy gaps Eg(C), Eg(Si), and Eg(Ge). Which order is correct?
- Eg(Ge) > Eg(Si) > Eg(C)
- Eg(Si) > Eg(C) > Eg(Ge)
- Eg(C) > Eg(Si) > Eg(Ge) ✓
- Eg(C) = Eg(Si) = Eg(Ge)
Answer: C. The approximate gaps are 5.4 eV for diamond, 1.1 eV for silicon, and 0.7 eV for germanium, giving the stated descending order.
Why not A: Germanium has the smallest of the three gaps, so placing it first reverses the observed trend.
Why not B: Carbon's approximately 5.4 eV gap is much larger than silicon's approximately 1.1 eV gap.
Why not D: A common valency does not force equal gaps because lattice spacing and bonding energies differ.
Pure silicon has 5.0 × 10^28 atoms m^-3 and is doped with 1 ppm pentavalent impurity. If ni = 1.5 × 10^16 m^-3 and donors are ionised, what is the approximate hole concentration?
- 4.5 × 10^9 m^-3 ✓
- 1.5 × 10^16 m^-3
- 5.0 × 10^22 m^-3
- 2.5 × 10^31 m^-3
Answer: A. One ppm gives ne ≈ 5.0 × 10^22 m^-3. From ne nh = ni², nh = 2.25 × 10^32/(5.0 × 10^22) = 4.5 × 10^9 m^-3.
Why not B: This repeats the intrinsic concentration even though donor doping greatly raises electron concentration and lowers holes.
Why not C: This is approximately the donor-supplied electron concentration, which is the majority rather than minority population.
Why not D: This resembles multiplying large concentrations and has neither the mass-action quotient nor a plausible carrier density.
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Questions
How many NEET questions are there on Semiconductor Electronics Materials Devices and Simple Circuits?
This chapter test has 30 questions — 10 easy, 14 medium and 6 hard — all written against the NCERT Class 12 chapter.
Is this NEET Physics chapter test free?
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Do the questions explain the wrong options?
Yes — every distractor carries its own explanation naming the specific misconception that makes a student pick it. That is the part most question banks skip, and it is the part that changes your next attempt.