Question

When a p-n junction diode is forward-biased ______

Options

• it acts as an insulator and no current flows through it.

• it offers a low resistance and a large current flows through it.

• it offers a high resistance and a small current flows through it.

• the width of depletion region increases.

Answer 1

When a p-n junction diode is forward-biased it offers a low resistance and a large current flows through it.

Explanation:

• In forward bias the p‑side is at a higher potential than the n‑side, so the external field opposes the internal barrier field and majority carriers (holes on the p–side and electrons on the n–side) are pushed toward the junction. This causes strong recombination and a large forward current the junction therefore behaves like a low resistance.
• The V–I characteristic shows a small current until the applied voltage overcomes the barrier (≈ 0.3 V for Ge, ≈ 0.7 V for Si), then the current rises rapidly with voltage consistent with a low forward resistance and large current flow.