EE 3320 Lecture : Notes 7
Document Summary
Dielectrics differ from conductors in that they have few (if any) free charges available for conduction. They do, however, have fixed, or bound, charges that influence the field within the material. Imagine the electron clouds surrounding the atoms constituting the medium while an em wave passes through. The electric field component of the wave alternately pulls the electrons one direction and the positive nucleus the other direction thereby establishing electric dipoles that try to align themselves with the oscillating field1. As you might imagine there is a slight lag in the alignment process as the field is rapidly changing. This polarization process results in a slight phase difference between the d -field and the e -field. Since the permittivity is the quantity relating these two fields, this phase difference is mathematically accommodated by writing the permittivity as a complex number, or or or o j j j r r.
