Properties of Conductors, Semiconductors, Insulators

Jul 11, 2024

Electrical Conductors, Semiconductors, and Insulators

3 Types of Materials

  1. Conductors: These materials can easily carry electricity from one place to another.
  2. Semiconductors: These materials conduct electricity with limited efficiency.
  3. Insulators: These materials do not easily carry electricity.

Conductor

  • Free Electrons: Conductors have many free electrons that move within the lattice structure of the metal.
  • Examples: Copper (Cu), Aluminium (Al)
  • Conductors can easily carry charge and energy from one place to another.
  • The charge resides on the surface of conductors.

Semiconductor

  • Conduct electricity with less efficiency compared to some metals.
  • Often made from Silicon (Si) and Germanium (Ge).

Insulator

  • Negligible Free Electrons: Insulators have negligible free electrons.
  • Examples: Glass, Rubber
  • In insulators, charge remains inside the material. The charge stays inside and there is less possibility of charge transfer.
  • All charges remain within the volume of the insulator.

Charging Methods

  1. Thermal Excitation

    • When a metal is heated, its electrons gain energy and can escape, making the metal positively charged.

  2. Photoelectric Effect

    • If a high-frequency light is shone on a metal, it can eject electrons, making the metal positively charged.

  3. Induction

    • If a large charge is placed near a metal, it attracts the free electrons of the metal, creating a positive charge.

Coulomb's Law

  • This law states that the attractive or repulsive force between two charged particles is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
  • Formula: $F = \frac{k \cdot |q1 \cdot q2|}{r^2}$
    • Here, $k$ is Coulomb's constant.

Force in Various Mediums

  • The magnitude of force depends on the medium.
  • The electrical effect varies in different mediums.
  • Permittivity of Vacuum ($ε_0$): $8.854 \times 10^{-12} \text{F/m}$
  • Relative Permittivity: How much the permittivity of a medium is as compared to the permittivity of a vacuum. For a static medium, this is equal to 1.

Principle of Superposition

  • If more than one charged particle exerts force at a point, their forces can be added vectorially. This creates a net force, causing the charge at that point to move.