Electrostatics

1. ELECTROMAGNETIC FIELD
THEORY
BY: G SAMBASIVA RAO
ASST.PROF/ECE DEPT.

2. UNIT – I
Electrostatics-I: Coulomb’s Law, Electric Field Intensity - Electric
Fields due to Continuous Charge Distributions – Line Charge, Surface
Charge, Volume Charge - Electric Flux Density - Gauss Law –
Applications of Gauss Law – Point Charge, Infinite Line Charge,
Infinite Sheet Charge - Electric Potential -Relations Between E and V.
Syllabus
UNIT – II
Electrostatics-II: The nature of dielectric materials, boundary
conditions for perfect dielectric materials. Capacitance, Several
capacitance examples: Parallel Plate Capacitor, Capacitance of a
Coaxial Cable, Spherical Capacitor. Derivations of Poisson’s and
Laplace’s equations. Current and current density, Energy density,
continuity of current.
UNIT – III
The Steady Magnetic Field: Biot-Savart’s Law, Ampere’s Circuital
Law, Magnetic Flux and Magnetic Flux Density, The scalar and vector
magnetic potentials. Magnetic Forces and Materials: Force on a
moving charge, force on a differential current element, force between
differential current elements, Magnetic Energy, the nature of magnetic
materials, magnetization and permeability, magnetic boundary

3. UNIT – IV
Time Varying Fields and Maxwell’s Equations: Faraday’s Law -
Transformer and Motional EMFs –Stationary Loop in Time Varying B
Field, Moving Loop in Static B Field, Moving Loop in Time
VaryingField - Displacement Current – Maxwell’s Equations in
Different Final Forms.
UNIT – V
Wave Equations: Waves equations for: a conducting medium, free
space – Relation between E and H in a Uniform plane wave - Wave
propagation: Lossless medium, Conducting medium, Good
Dielectric, Good Conductor - Poynting Vector and Poynting theorm -
Reflection of a Plane wave at Normal Incidence - Reflection of a
Plane wave at Oblique.
TEXTBOOKS:
1. Matthew N.O. Sadiku, Elements of Electromagnetics, Oxford University
Press, 3rd edition, 2008.
2. William H. Hayt Jr. and John A. Buck, Engineering Electromagnetics, Tata
McGraw-Hill publications,7th edition, 2006.
3. G S N Raju, Electromagnetic Field Theory and transmission lines, 1st
Edition, Pearson Education India, 2005.

4. UNIT-I : Electrostatics -I

7. Key points

10. TWO ELECTRONS ARE PLACED 1M
APART.WHAT IS THE FORCE BETWEEN
THEM?

13. •Electric Fields have a magnitude and
direction
•Vector Quantities
•Lines go away from positive
•Lines go toward negative

16. Electric Field Intensity

18. Electric Fields due to Continuous
Charge Distributions

20. Electric Field Strength due to Infinite Line Charge

23. Electric Field Strength due to Surface Charge
Density

29. FIELD DUE TO VOLUME CHARGE DENSITY,

32. ELECTRIC
FLUX

33. SALIENT FEATURES OF
ELECTRIC FLUX
1. It is independent of the medium.
2. The electric field creates a force on a charge and hence the
charge moves along a certain path. This path is called the flux
line.
3. The force between two charges acts along a certain path. This
path is also called the flux line.
4. Magnitude of flux depends only on the charge from which it
originates.
5. The flux lines are equal to the charge in Coulombs.
6. Flux line is only an imaginary line.
7. Its direction is the same as that of the electric field.

34. ELECTRIC FLUX DENSITY

35. Problem: If an electric field in free space is given by E = ax +
2ay + 5az V/m,
find the electric flux density.

36. Problem 2.A point charge, Q = 10nC is at the origin in
free space. Find
the electric field at P (1, 0, 1). Also find the electric flux
density at P.

40. GAUSS LAW
Gauss’s law It states that the net flux passing through
any closed surface is equal to the charge enclosed by
that surface, that is,
Consider a spherical surface which encloses
a charge Q at its centre (Fig.)

43. GAUSS LAW IN POINT FORM
Gauss’s law in point form states that the divergence of electric flux
density is equal to the volume charge density, that is,