Drude model
The
Drude model of
electrical conduction was developed in the
1900s by Paul Drude to explain the transport properties of
electrons in materials. The Drude model is the application of
kinetic theory to electrons in a solid. It assumes that the material contains immobile positive ions and an "electron gas" of classical, non-interacting electrons of density
n, each of whose motion is damped by a frictional force, due to collisions of the electrons with the ions, characterized by a relaxation time
τ. Under an applied
electric field E, the current density
j is
where
e is the
charge of the electron. The
conductivity σ is then
- .
This simple classical model does a surprisingly good job of explaining DC and AC conductivity in
metals, the
Hall effect, and
thermal conductivity (due to electrons) in metals.