Electricity and Electronic Conduction

Electrons are negatively charged particles that carry electric charges. When voltage is applied between two points of a conductor like a metal wire, electrons start moving from one point to another due to the attraction and repulsion forces they experience. As these electrons move, they experience electrical resistance, which depends on several factors including the material's atomic structure, temperature, and pressure.

In metals, where the outermost electron shell is partially filled or half-filled, there is no net force acting on electrons, hence they can easily travel through the metal lattice. This property makes metals excellent conductors of electricity. However, if a metal's outermost electron shell is completely filled or empty, it becomes difficult for electrons to move, leading to poor conductivity. This phenomenon explains why some metals like copper, silver, and gold have high electrical conductivities while others like mercury and lead have low electrical conductivities.

There are three primary types of electronic conduction:

1. Ohmic Conduction: In this type of conduction, the electric current rises linearly with the applied voltage. It is the most common type of conduction in metals and is considered a 'normal' state of conduction. Ohmic conductors are also known as linear conductors.

2. Non-Ohmic Conduction: In this type of conduction, the electric current does not rise linearly with the applied voltage. Instead, it rises exponentially, logarithmically, or even shows a plateau, depending on the material and conditions. This type of conduction is often seen in semiconductors and other non-metallic materials.

3. Superconductivity: In some materials, at extremely low temperatures, the electrical resistance is driven to zero, and the material becomes a perfect conductor of electricity. This phenomenon is known as superconductivity.

In summary, electric current flow in metallic conductors is primarily governed by the movement of electrons, which is influenced by various factors such as the material's atomic structure, temperature, and pressure. The current flow can follow three primary types of conduction: ohmic, non-ohmic, and superconductivity. Understanding these aspects is vital for designing and optimizing electrical circuits and devices.