Question

On increasing the reverse bias to a large value in a PN junction diode, current

• A. Increases slowly
• B. Remains fixed
• C. Suddenly increases
• D. Decreases slowly

Hint:

A reverse-biased PN junction diode conducts heavily only after breakdown voltage is reached — leading to a sudden rise in current.

Answer 1

The Correct Option is C

In a PN junction diode under reverse bias, a small leakage current flows due to minority carriers.
As the reverse voltage is increased and reaches a certain critical value (breakdown voltage), the electric field becomes strong enough to accelerate minority carriers, causing impact ionization.
This leads to avalanche breakdown, and the current suddenly increases.
This phenomenon is exploited in Zener and avalanche diodes.