Question

A PN junction diode is used as:

• A. An amplifier
• B. A rectifier
• C. An oscillator
• D. A modulator

Hint:

A PN junction diode allows current flow in only one direction, making it suitable for rectification. It is the key component in half-wave and full-wave rectifiers, which are used in power supplies to convert AC to DC.

Answer 1

The Correct Option is B

Step 1: Understanding PN Junction Diodes A PN junction diode is a semiconductor device that allows current to flow in one direction (forward bias) while blocking it in the opposite direction (reverse bias). This property makes it useful in rectification, where AC is converted to DC. 
Step 2: Function of a Rectifier A rectifier is an electrical device that converts alternating current (AC) to direct current (DC) by allowing current flow in only one direction. PN junction diodes are used in: - Half-wave rectifiers (using a single diode), - Full-wave rectifiers (using multiple diodes in bridge configuration). 
Step 3: Evaluating the Given Options - An amplifier (Incorrect): Amplifiers require transistors, not diodes.
- A rectifier (Correct): PN junction diodes are essential components in rectifiers, converting AC to DC. 
- An oscillator (Incorrect): Oscillators require feedback circuits with inductors, capacitors, or transistors. 
- A modulator (Incorrect): Modulation is performed using transistors and operational amplifiers rather than simple diodes. 
Step 4: Conclusion Thus, a PN junction diode is primarily used as a rectifier, which converts AC to DC.