1. 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

2. 1.5
The Electric Field

3. 1.5-
The Electric Field
is a force field acting on charges by virtue of the property of charge.
Coulomb’s Law

4. D1.13(b)
From the construction, it is evident that the resultant force is directed away from the center of the square. The magnitude of this resultant force is given by
Q2/4pe0(2a2)
Q2/4pe0(4a2)
Q2/4pe0(2a2)

6. Electric Field Intensity, E
is defined as the force per unit charge experienced by a small test charge when placed in the region of the field.
Thus
Units:
Sources: Charges;
Time-varying
magnetic field

7. Electric Field of a Point Charge
(Coulomb’s Law)

8. Constant magnitude surfaces are spheres centered at Q.
Direction lines are radial lines emanating from Q.
E due to charge distributions
(a) Collection of point charges

9. Ex. a
Electron (charge e and mass m) is displaced from the origin by D (<< d) in the +x-direction and released from rest at t = 0. We wish to obtain differential equation for the motion of the electron and its solution.

10. For any displacement x,
is directed toward the origin,
and

11. The differential equation for the motion of the electron is
Solution is given by

12. Using initial conditions and at t = 0, we obtain
which represents simple harmonic motion about the origin with period

13. (b) Line Charges
Line charge
density, rL (C/m)
(c) Surface Charges
Surface charge
density, rS (C/m2)
(d) Volume Charges
Volume charge
density, r (C/m3)

14. Ex. Finitely-Long Line Charge

16. Infinite Plane Sheet of Charge of Uniform Surface Charge Density
rS0 a

18. rS0

19. D1.16
Given
rS1
rS2
rS3

20. Solving, we obtain
(a)
(b)
(c)
(d)