Question

In this I-V characteristic curve of a Zener diode, regions 1 and 2 respectively indicate

A. forward bias and reverse bias regions
B. reverse bias and forward bias regions
C. forward bias regions only
D. reverse bias regions only

Answer 1

A Zener diode is a diode which allows the current to flow in the opposite/backward direction when the reverse voltage is reached. Consider the behavior of Zener diodes in both forward and reverse biasing.

Complete answer:
In the forward bias, the behavior of the Zener diode is ordinary like a silicon diode. In reverse bias, when the reverse bias voltage is greater than a particular voltage, the breakdown of the Zener voltage occurs, denoted by ${V_Z}$. The reverse current suddenly increases at a certain value of reverse voltage. According to this, we can conclude that region 1 represents the forward bias which is a normal behaviour and region 2 represents the reverse bias condition where the breakdown occurs.

Hence, in this I-V characteristic curve of a Zener diode, regions 1 and 2 respectively indicate forward bias and reverse bias regions.

Therefore, option (A) is correct.

Additional information:
Zener diodes are usually used in the reverse bias, meaning anode to the negative and cathode to the positive side of the voltage source. A large change in the reverse current brings a slight change in the breakdown voltage.

Note: The breakdown voltage/Zener voltage remains almost constant, variations are negligible. The Zener diode can be used in another way. This constant voltage can be applied across a load. Remember the changes in ${V_Z}$ is negligible and ${V_Z}$ is not constant.