Concept:A solar cell is an unbiased PN junction that absorbs incident photons with \( hf > E_g \), generating an open-circuit photovoltage (photovoltaic effect) that drives current through an external load.
Formula:$$V_{\text{load}} = V_{\text{oc}} - I R_s \quad \text{where } V_{\text{oc}} = \frac{k T}{q} \ln\left(\frac{I_L}{I_0} + 1\right)$$
Solution:- A solar cell requires no external biasing battery.
- Incident sunlight creates electron-hole pairs that are separated by the built-in junction electric field.
- This charge accumulation generates a DC potential difference across the terminals, converting light energy into electrical power.
Why other options are incorrect:- Option A: Applying an external forward bias consumes electrical power rather than generating it.
- Option B: Reverse avalanche breakdown is used in voltage-regulating Zener diodes, not solar energy harvesting.
- Option D: External AC biasing disrupts normal unidirectional solar cell 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.