Edward C. Jordan Memorial Offering of the First Course under the Indo-US Inter-University Collaborative Initiative in Higher Education and Research: Electromagnetics for Electrical and Computer Engineering by Nannapaneni Narayana Rao Edward C. Jordan Professor of Electrical and Computer Engineering University of Illinois at Urbana-Champaign Urbana, Illinois, USA Amrita Viswa Vidya Peetham, Coimbatore July 10 – August 11, 2006

4.1 Conductors and Semiconductors

Material Media can be classified as (1) Conductors and Semiconductors (2) Dielectrics (3) Magnetic materials – magnetic property Conductors and Semiconductors Conductors are based upon the property of conduction, the phenomenon of drift of free electrons in the material with an average drift velocity proportional to the applied electric field. electric property

In semiconductors, conduction occurs not only by electrons but also by holes – vacancies created by detachment of electrons due to breaking of covalent bonds with other atoms. The conduction current density is given by Ohm’s Law at a point

conductors semiconductors

Ohm’s Law s Ohm’s Law

D4.1 (a) For cu, (b)

(c) From

Conductor in a static electric field

rS = –e0E0 rS0 –rS0 E = – e0 az rS = e0E0 rS = –e0E0 rS = e0E0 rS = –e0E0 rS = e0E0

P4.3 (a) rS1 rS2

(b) Write two more equations and solve for the four unknowns. rS11