Forward biasing of a p-n junction

The correct answer is Option (2) → decreases its resistance

In forward bias the p side is joined to the positive terminal of the battery. The applied voltage opposes the built-in junction voltage, so the depletion layer becomes thinner and the potential barrier becomes lower, and a large current flows.

Option (1) increases its resistance — Incorrect. The resistance of a forward-biased junction is low, not high.

Option (2) decreases its resistance — Correct. The thinner depletion layer and lower barrier let carriers cross easily, so the resistance falls.

Option (3) increases the junction field — Incorrect. The applied field opposes the junction field, so the junction field decreases.

Option (4) increases the potential barrier — Incorrect. The potential barrier is reduced in forward bias and increased in reverse bias.

NCERT (2026-27):
p-n Junction Diode Under Forward Bias – “When an external voltage V is applied across a semiconductor diode such that p-side is connected to the positive terminal of the battery and n-side to the negative terminal [Fig. 14.13(a)], it is said to be forward biased.”

p-n Junction Diode Under Forward Bias – “… The direction of the applied voltage (V) is opposite to the built-in potential V₀. As a result, the depletion layer width decreases and the barrier height is reduced [Fig. 14.13(b)].”

p-n Junction Diode Under Reverse Bias – “… The forward bias resistance is low as compared to the reverse bias resistance.”