This document discusses Gauss's law and its applications in solving complex electrostatic problems involving unique symmetries like cylindrical, spherical, or planar symmetry. It provides 4 examples of using Gauss's law to calculate electric field intensity due to (1) a point charge, (2) an infinite line charge, (3) an infinite plane sheet, and (4) a charged sphere. It also briefly defines dielectrics as materials where charges are bound and unable to migrate in response to an applied electric field, instead causing polarization.
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EMTL Class10.pptx
1. Electromagnetic waves &
Transmission lines
By
M. Gnanapriya,
Head Of the Department of ECE
Gokula Krishna College of Engineering, Sullurpet
Date: 02.06.2021
Gausss law& its applications
convection & conduction current
22-09-2022 1
3. Gauss law can be used to solve complex electrostatic problems involving unique
symmetry like cylindrical , spherical or planer symmetry.
1. Electric field due to point charge
Consider a point charge located at origin. We choose a spherical Gaussian
surface of radius r where the electric field intensity is going to be measured.
According to Gauss law
r
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4. 2. Electric field due to an infinite line charge
Consider an infinite line of uniform charge density l c/m Lies along z axis.
To calculate electric field intensity we assume a cylindrical Gaussian surface of
length l to satisfy symmetry condition. The electric field E is the radial in the
direction of flux. So the flux through the end of cylindrical surface is zero. Ie.
E.ds2=E.ds3=0 (COS90=0)
According to Gauss law
l
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5. 3. Electric field due to an infinite Plane sheet
Consider an infinite sheet uniform charge density s c/m 2. To calculate
electric field intensity we assume a cylindrical Gaussian surface whose axis is
normal to the plane of sheet. We shall consider the electric flus only from tow
ends of the cylinder. Because curved space areal & E are normal to each other so
the flux it produces is zero.
According to Gauss law
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6. 4. Electric field intensity outside the sphere charge
Consider a sphere of radius R with uniform charge density v c/m3. To
calculate electric field intensity we assume a spherical Gaussian surface of radius r
which experiences uniform electric field E because of sphere charge.
According to Gauss law
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10. 22-09-2022 10
DIELECTRIC
In a dielectric or insulator charges are bound and they are not free to migrate. The conductivity of an insulator
ideally zero. If a field is applied to an insulator there may not be any migration of charge but it can produce
polarization of the dielectric displacement of electrons with respect to equilibrium position.
Example: wood, glass, paraffins (plastics) are good insulators