Electromagnetic fields:Units and constants

1. EC8451- ELECTROMAGNETIC FIELDS
Dr.K.G.SHANTHI
Professor/ECE
shanthiece@rmkcet.ac.in
UNITS AND CONSTANTS

2. ✘ Electromagnetics is a branch of physics or electrical engineering that
deals electric and magnetic phenomena.
✘ Electromagnetics is the study of the effects of electric charges at rest
and in motion.
✘ Both positive and negative charges are sources of an electric field.
✘ Moving Charges produce a current, which gives rise to a magnetic field.
✘ A Field is a spatial distribution of a quantity, which may or may not be a
function of time. A time-varying electric field is accompanied by a
magnetic field, and vice versa resulting in electromagnetic field.
✘ Circuit theory Vs Field theory
✘ Inductive Approach Vs Deductive approach
✘ Electromagnetic model
2
UNIT-I: INTRODUCTION

3. 3
https://phet.colorado.edu/sims/html
/charges-and-fields/latest/charges-
and-fields_en.html
Positive and Negative charges
are sources of an electric field

4. UNITS AND CONSTANTS
4
Four Fundamental SI Units
• All other units used in electromagnetics, are derived units expressible in
terms of meters, kilograms, seconds and amperes.
• For example, the unit for charge, coulomb (C), is ampere-second (A.s);
the unit for electric field intensity (V/m) is kg.m/A.s3

5. UNITS AND CONSTANTS
5
Three universal constants
ε0 is the proportionality constant
between the electric flux density
D and the electric field intensity E
in free space
https://www.youtube.com/watch?v=5x8kj02ar34
1. Permittivity of free space ε0:
• The permittivity is the property of the material which measures the
opposition generated by the material in the development of an electric field.
• Permittivity of free space ε0 represents the capability of a vacuum to
permit electric fields.

6. UNITS AND CONSTANTS
6
Three universal constants
2. Permeability of free space μ0:
Measures the ability of the material to allow the magnetic lines of
force to pass through it
μ0 is the proportionality constant between the magnetic flux density B
and the magnetic field intensity H in free space
3. Velocity of electromagnetic wave in free space, c;