Interactive Animations of Electromagnetic waves

-A basic PPT for better understand of EMFT

BYS Naga Kishore Bhavanam

B.Tech., MBA, M.Tech., (Ph.D)Assistant Professor

University College of Engineering & Technology

Acharya Nagarjuna UniversityGuntur

Hellow: +91-99895 41444Email: kishore.ece.anu@gmail.com

Introduction to Electromagnetic Fields

• Electromagnetics is the study of the effect of charges at rest and charges in motion.

• Some special cases of electromagnetics:– Electrostatics: charges at rest– Magnetostatics: charges in steady motion

(DC)– Electromagnetic waves: waves excited

by charges in time-varying motion

Introduction to Electromagnetic Fields

Maxwell’sequations

Fundamental laws of classical electromagnetics

Special cases

Electro-statics

Magneto-statics

Electro-magnetic

waves

Kirchoff’s Laws

Statics: 0t

d

Geometric Optics

TransmissionLine

Theory

CircuitTheory

Input from other

disciplines

Introduction to Electromagnetic Fields

Transmitter and Receiver are connected by a “field.”

A field is a spatial distribution of a quantity; in general, it can be either scalar or vector in nature.

Introduction to Electromagnetic Fields

• A scalar is a quantity having only an amplitude (and possibly phase).

• A vector is a quantity having direction in addition to amplitude (and possibly phase).

Examples: voltage, current, charge, energy, temperature

Examples: velocity, acceleration, force

• Fundamental vector field quantities in electromagnetics:– Electric field intensity

– Electric flux density (electric displacement)

– Magnetic field intensity

– Magnetic flux density

units = volts per meter (V/m = kg m/A/s3)

units = coulombs per square meter (C/m2 = A s /m2)

units = amps per meter (A/m)

units = teslas = webers per square meter (T = Wb/ m2 = kg/A/s3)

E

D

H

B

Introduction to Electromagnetic Fields

Introduction to Electromagnetic Fields • Universal constants in

electromagnetics:– Velocity of an electromagnetic wave (e.g.,

light) in free space (perfect vacuum)

– Permeability of free space

– Permittivity of free space:

– Intrinsic impedance of free space:

H/m 104 70

F/m 10854.8 120

1200

m/s 103 8c

0

00

00

1

c

. In free space:HB 0

ED 0

• Relationships involving the universal constants:

Introduction to Electromagnetic Fields

Electromagnetic Waves and Their Propagation Through the Atmosphere

Electromagnetic waves:

Interact with matter in four ways:

Reflection:

Refraction:

Scattering:

Diffraction:

ElectromagnetismMaxwell’s equations describe electromagnetic waves but they are hard to grasp intuitively.

In our minds, most of us just have vague images of E and B vectors oscillating somewhere in space.

If we ourselves do not really understand electromagnetic waves, how can we teach them effectively?

Animation makes it clear

)/sin( txAEy Vertically (y axis) polarized wave having an amplitude A, a wavelength of and an angular velocity (frequency * 2) of , propagating along the x axis.

GNUPLOT: equation plotting program

Vertical

Horizontal

)/sin( txAEy

Plane-polarized light

)/sin( txAEz

Right circular

Left circular

Circularly polarized light

)90/sin( txAEy

)/sin( txAEz

)90/sin( txAEy

)/sin( txAEz

Interaction of light and matter: Absorption

)/sin( txAeE xy

Material with an extinction coefficient

The light gets weaker (its amplitude drops)

In Out

Interaction of light and matter: Refraction

In Out

Material with an index of refraction n

The light slows down inside the material, therefore its wavelength becomes shorter and its phase gets shifted

)/sin( tnxAEy

Circular dichroism

In Out

Material having different extinction coefficients for right and left circularly polarized lights: R and L

Plane-polarized light becomes elliptically polar

)90/sin()90/sin( txAetxAeE xxy

LR

)/sin()/sin( txAetxAeE xxz

LR

Circular bi-refringence

In Out

Material having different refraction indices for right and left circularly polarized lights: nR and nL

The plane of polarization of plane-polarized light gets rotated

)90/sin()90/sin( LR txnAtxnAEy

)/sin()/sin( R txnAtxnAE Lz

Circular dichroism AND bi-refringence

In Out

Material having different extincion coefficients AND refraction indices for right and left circularly polarized lights: R and L AND nR and nL

Plane polarized light gets elliptically polar, with the great axis of the ellipse being rotated relative to the original plane of polarization

)90/sin()90/sin( LR txnAetxnAeE xxy

LR

)/sin()/sin( LR txnAetxnAeE xxz

LR

By

Naga kishore