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.