interactive animations
DESCRIPTION
EMFTTRANSCRIPT
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: [email protected]
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