Question: 3: The incorrect statement about the property of a Zener diode is :
(1) Zener voltage remains constant at breakdown
(2) It is designed to operate under reverse bias
(3) Depletion region formed is very wide
(4) p and n regions of zener diode are heavily doped
Answer: Option (3)
Explanation:
A Zener diode is a special type of diode designed to operate in the reverse bias region, specifically in the breakdown region.
When a Zener diode operates at breakdown, the Zener voltage remains nearly constant, so statement (1) is correct.
Zener diodes are always used in reverse bias for voltage regulation, so statement (2) is also correct.
The p and n regions of a Zener diode are heavily doped.
Heavy doping results in a thin depletion layer and a strong electric field, which causes breakdown at a low voltage.
Hence statement (4) is correct.
Because of heavy doping, the depletion region in a Zener diode is very narrow, not wide.
Therefore, statement (3) is incorrect.