Electronic Devices – JEE Mains Physics
1. Semiconductors
- Semiconductors are materials that have conductivity between conductors and insulators. The conductivity of semiconductors can be increased by doping, introducing impurities into the material.
2. Semiconductor Diode: I-V Characteristics in Forward and Reverse Bias
- A semiconductor diode is a device that allows current to flow in one direction only. In forward bias, the diode conducts current after a threshold voltage is reached. In reverse bias, the current is negligible until the breakdown voltage is exceeded.
3. Diode as a Rectifier
- Diodes are widely used as rectifiers, converting alternating current (AC) into direct current (DC). In a half-wave rectifier, the diode allows current to pass during only one half of the AC cycle, while a full-wave rectifier uses two diodes to conduct during both halves of the cycle.
4. I-V Characteristics of LED
- The LED (Light Emitting Diode) exhibits the property of emitting light when current passes through it. The I-V characteristics show that the diode has a forward voltage, and its emission intensity increases with the forward current.
5. The Photodiode
- A photodiode is a diode that generates a photocurrent when illuminated by light. It works in reverse bias, and the current produced depends on the intensity of the light incident on the diode.
6. Solar Cell
- A solar cell is a device that converts light energy directly into electrical energy using the photovoltaic effect. It is essentially a photodiode optimized for energy generation from sunlight.
7. Zener Diode and Zener Diode as Voltage Regulator
- The Zener diode is a special-purpose diode designed to allow current to flow in the reverse direction when the voltage exceeds a certain value (Zener breakdown). It is commonly used as a voltage regulator to maintain a constant voltage level in circuits.
8. Logic Gates (OR, AND, NOT, NAND, NOR)
- Logic gates are the fundamental building blocks of digital circuits. The most common logic gates include:
- OR Gate: Outputs 1 if at least one input is 1.
- AND Gate: Outputs 1 if both inputs are 1.
- NOT Gate: Outputs the opposite of the input (inverts the input).
- NAND Gate: Outputs 0 only when both inputs are 1.
- NOR Gate: Outputs 0 if at least one input is 1.