Concept:In reverse bias, the external voltage applies a positive potential to the N-region and a negative potential to the P-region. This external field aligns with the built-in field.
Formula:$$\vec{E}_{\text{net}} = \vec{E}_{\text{built-in}} + \vec{E}_{\text{applied}}$$
Solution:- Both \( \vec{E}_{\text{built-in}} \) and \( \vec{E}_{\text{applied}} \) point from the N-region toward the P-region.
- The net electric field increases across the junction.
- This stronger field draws mobile majority carriers farther from the interface, widening the depletion region and increasing its barrier resistance.
Why other options are incorrect:- Option B: Field cancellation occurs under forward bias, not reverse bias.
- Option C: A steady DC reverse voltage produces a static space-charge field rather than an oscillating electromagnetic field.
- Option D: Reverse bias opposes majority carrier motion and prevents forward current.
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.