Optical conductivity
Encyclopedia
Optical conductivity is one of the powerful tools for studying the electronic states in materials.
If a system is subjected to an external electric field
Electric field
In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...

 then, in general, a redistribution of charges occurs and currents are induced. For small enough fields, the induced polarization
Induced polarization
Induced polarization is a geophysical imaging technique used to identify subsurface materials, such as ore. The method is similar to electrical resistivity tomography, in that an electric current is induced into the subsurface through two electrodes, and voltage is monitored through two other...

and the induced currents are proportional to the inducing field.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK