Concept:Forward bias applies an external electric field that opposes the built-in potential barrier, reducing the net junction potential to \( V_0 - V_F \) and narrowing the depletion layer.
Formula:$$W = \sqrt{\frac{2 \epsilon_s (V_0 - V_F)}{q} \left( \frac{1}{N_A} + \frac{1}{N_D} \right)} \propto \sqrt{V_0 - V_F}$$
Solution:- The forward voltage \( V_F \) counteracts the built-in potential \( V_0 \).
- As \( V_F \) approaches \( V_0 \), the net potential barrier decreases, reducing the width \( W \) of the depletion layer and allowing majority carriers to cross the junction.
Why other options are incorrect:- Option A: Depletion width decreases under forward bias; it increases under reverse bias.
- Option B: The depletion width changes with applied bias voltage.
- Option C: Depletion layer expansion occurs under high reverse bias, not forward bias.
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.