Zener diode is used as (A) Full. wave rectifier (B) amplifier (C) A.C. voltage regulator (D) D.C. voltage regulator

A Zener diode is a type of diode designed to work in the breakdown region or reverse-bias. It allows current to flow in the reverse direction when the voltage across its terminals exceeds the Zener voltage. The main function of a Zener diode is to maintain a constant voltage across its terminals.

(A) Full wave rectifier - A full wave rectifier is used to convert an alternating (AC) voltage to direct (DC) voltage. A Zener diode is not typically used for this purpose, as it does not offer the necessary rectification properties. (B) Amplifier - An amplifier is a device that increases the amplitude of a signal. A Zener diode is not suitable for this application, as it does not provide amplification. (C) AC voltage regulator - An AC voltage regulator is a device used to maintain a constant output voltage in an AC circuit. While the Zener diode can maintain constant voltage under reverse-bias conditions, it is not designed to regulate AC voltage. (D) DC voltage regulator - A DC voltage regulator is a device used to maintain a constant output voltage in a DC circuit. A Zener diode can be utilized in this application because it maintains a constant breakdown voltage, making it an appropriate device for regulating DC voltage. Based on the analysis above:

The correct application of a Zener diode is as a (D) D.C. voltage regulator.