If the forward voltage in a p-n junction diode is increased, the width of the depletion region:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → decreases
The forward voltage V acts opposite to the built-in potential \( V_0 \) of the junction, so the effective barrier is \( V_0 - V \). The larger the forward voltage, the lower the barrier and the fewer uncovered charges are needed to balance it, so the depletion region becomes narrower.
Note: The same question was also asked in CUET (UG) 2023 on 25-05-2023 (Slot 3), and a similar question in CUET (UG) 2026 on 24-05-2026 (Slot 2).
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. … 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)].”