Physics Electronics PMDC Conceptual Practice
PMDC Verified Question 61 of 494
In an \( \text{N-type} \) extrinsic semiconductor, electrical conduction is primarily governed by:
A
Electrons as majority carriers and holes as minority carriers
B
Holes as majority carriers and electrons as minority carriers
C
Equal populations of free electrons and positive ions
D
Bound positive donor ions moving across the crystal lattice
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Electrons as majority carriers and holes as minority carriers
Concept:

Pentavalent doping introduces abundant extra free electrons, making electrons the majority carriers while thermally generated holes remain the minority carriers.

Formula:

$$n_e \gg n_h \quad (\text{in N-type semiconductor})$$

Solution:

  • Each donor atom contributes one free electron to the conduction band without creating a corresponding hole.


  • Therefore, electrons vastly outnumber thermally generated holes (\( n_e \gg n_h \)).


Why other options are incorrect:

  • Option B: Describes carrier populations in a P-type semiconductor.


  • Option C: Bound ions are immobile and do not participate in charge conduction.


  • Option D: Donor ions are permanently locked in the crystal lattice and cannot move.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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