Question

Zener diode is used as-
A. Half wave rectifier
B. Full wave rectifier
C. A.C. voltage stabilizer
D. D.C. voltage stabilizer

Answer 1

Zener diode is defined as a properly doped $p - n$ junction diode which works in the breakdown region without damaging itself. A Zener diode is also known as a breakdown diode and it is mainly used as a voltage regulator.

Complete step by step answer:
The basic symbol of a Zener diode is given by

A Zener diode can be used as a voltage regulator or voltage stabilizer to provide a constant voltage from a source whose voltage may fluctuate over a wide range. The circuit diagram using a Zener diode as a voltage stabilizer is shown below.

The Zener diode is connected across the fluctuating voltage source through a dropping resistor of resistance ${R_S}$ . The constant voltage supply is obtained across the load resistance ${R_L}$.When the input voltage increases, the resistance of the zener diode decreases, and hence the current through the diode increases to a high value. As a result of this, a large voltage drop occurs across the dropping resistance ${R_S}$. Hence, the output voltage drop across ${R_L}$ is maintained to the desired value.

When the input value decreases, the current through the diode also increases. So now a small voltage drop takes place across the resistance ${R_S}$ and the output voltage across ${R_L}$ is maintained at the desired constant value.Thus, we get a constant voltage in spite of fluctuating input voltage. Hence, the Zener diode acts as a voltage regulator. Therefore, the Zener diode is used as an A.C. voltage regulator.

Hence, option C is the correct option.

Note: The breakdown voltage of zener voltage ${V_Z}$ depends on the concentration of doping. Both $n$ and $p$ regions of the Zener diode are heavily doped.The depletion layer of a heavily doped $p - n$ junction diode is very thin.