In a p-n junction, the magnitude of the drift current is lower than the magnitude of the diffusion current when the junction is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → forward biased
In a p-n junction the diffusion current (majority carriers crossing the barrier) and the drift current (minority carriers swept across by the junction field) oppose each other.
Option (1) either forward biased or reverse biased — Incorrect. Diffusion exceeds drift only in forward bias; in reverse bias the drift current is the larger one.
Option (2) forward biased — Correct. Forward bias lowers the barrier, so many more majority carriers diffuse across; diffusion current exceeds drift current.
Option (3) reverse biased — Incorrect. Reverse bias raises the barrier and cuts diffusion, so the drift current is larger.
Option (4) under equilibrium — Incorrect. In equilibrium there is no net current, so the two are equal in magnitude.
NCERT (2026-27):
p-n Junction Diode Under Reverse Bias – “… The drift current is of the order of a few μA. This is quite low because it is due to the motion of carriers from their minority side to their majority side across the junction. The drift current is also there under forward bias but it is negligible (μA) when compared with current due to injected carriers which is usually in mA.”