Conductors, insulators, and semiconductors

1. Conductors

1. Conductors are materials that allow the easy flow of electric current.
2. Their conductivity is due to the presence of free electrons.
3. Examples include metals such as copper, aluminum, and silver.
4. Conductors have very low resistivity (10⁻⁶ to 10⁻⁸ Ω·m).
5. They are widely used in electrical wiring and electronic circuits.

2. Insulators

1. Insulators are materials that resist the flow of electric current.
2. Their atomic structure does not allow free movement of electrons.
3. Examples include rubber, glass, and plastic.
4. Insulators have very high resistivity (10⁸ to 10¹⁴ Ω·m).
5. They are used for insulating cables and as protective coatings in electrical devices.

3. Semiconductors

1. Semiconductors are materials that have intermediate conductivity between conductors and insulators.
2. At low temperatures, they act as insulators, and at higher temperatures, their conductivity increases.
3. Examples include silicon and germanium.
4. Their resistivity lies between 10⁻³ and 10³ Ω·m.
5. Semiconductors are the backbone of modern electronics, including diodes and transistors.

4. Difference Between Conductors, Insulators, and Semiconductors

1. Conductors: High conductivity and low resistivity.
2. Insulators: Low conductivity and high resistivity.
3. Semiconductors: Conductivity depends on temperature and doping.

5. Band Theory of Solids

1. The valence band is the highest energy band occupied by electrons in an atom.
2. The conduction band is the next higher energy band where electrons can move freely.
3. Conductors: The valence and conduction bands overlap, allowing free flow of electrons.
4. Insulators: A large energy gap exists between the valence and conduction bands.
5. Semiconductors: A small energy gap exists, making them conduct under certain conditions.

6. Applications of Semiconductors

1. Diodes: Used for rectification, converting AC to DC.
2. Transistors: Used as amplifiers and switches in electronic circuits.
3. Solar cells: Convert sunlight into electrical energy using semiconductors.
4. Integrated Circuits (ICs): Comprise millions of semiconductor components on a chip.
5. LEDs: Emit light when current passes through a semiconductor material.

7. Importance in Modern Electronics

1. Semiconductors form the foundation of microprocessors and computer chips.
2. They are crucial in developing communication devices like smartphones and radios.
3. Used in power electronics, controlling and converting electrical power efficiently.
4. Semiconductors have revolutionized the fields of automation and robotics.