**Drude model** The Drude model of electrical conduction was proposed to explain the transport properties of electrons in materials (especially metals).

The model is an application of kinetic theory.

The model assumes that the microscopic behavior of electrons in a solid may be treated classically. In the model the solid is thought of as a sea of electrons bouncing off heavier, relatively immobile positive ions.

The atoms condensed into a solid give up their loosely bound valence electrons, which are free to wander through the metal and lead to conduction of charge and energy/heat.

The two most significant results of the Drude model are an electronic equation of motion and a linear relationship between current density J and electric field E.

The amount of current j produced by an electric field E applied to a metallic sample can then be shown to be related to the number of carriers (carrier density n) and the ease with which theese carriers are accelerated (τ (tau), the time between collisions that randomise the electron flow)

j=σE

where

j = current

σ = conductivity = 1/ρ = the inverse of the resistivity

E = electric field

__Source:__ Wikipedia - Drude model

http://en.wikipedia.org/wiki/Drude_model Drude and Sommerfeld theory of metals

http://tau.nanophys.kth.se/cmp/hall/node1.html