On increasing the reverse bias across a p-n junction diode to a large…

The correct answer is Option (4) → suddenly increases

Under reverse bias, a p-n junction diode passes only a very small current (of the order of \( \mu\mathrm{A} \)). This current hardly changes with the voltage until the reverse voltage reaches the breakdown voltage \( V_{\mathrm{br}} \).

Option (1) remains fixed — Incorrect. The reverse current stays nearly constant only up to the breakdown voltage. A large reverse bias takes the diode past this limit.

Option (2) decreases slowly — Incorrect. A larger reverse bias never reduces the reverse current. Below breakdown it stays almost the same, and at breakdown it rises.

Option (3) increases slowly — Incorrect. Below breakdown, the current hardly depends on the voltage. At breakdown, the rise is steep and sudden.

Option (4) suddenly increases — Correct. At \( V=V_{\mathrm{br}} \), the reverse current rises sharply. A small rise in voltage then gives a big jump in current. The diode can be destroyed unless the current is limited.

NCERT (2026-27):
p-n Junction Diode under Reverse Bias – “The current under reverse bias is essentially voltage independent upto a critical reverse bias voltage, known as breakdown voltage (V_br). When V = V_br, the diode reverse current increases sharply. Even a slight increase in the bias voltage causes large change in the current.”