Slide Presentations for ECE 329, Introduction to Electromagnetic Fields, to supplement

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Slide Presentations for ECE 329,Introduction to
Electromagnetic Fields,to supplement Elements
of Engineering Electromagnetics, Sixth Edition

• by
• Nannapaneni Narayana Rao
• Edward C. Jordan Professor of Electrical and
  Computer Engineering
• University of Illinois at Urbana-Champaign,
  Urbana, Illinois, USA
• Distinguished Amrita Professor of Engineering
• Amrita Vishwa Vidyapeetham, Coimbatore, Tamil
  Nadu, India

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• 1.5
• The Electric Field

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• The Electric Field
• is a force field acting on charges by virtue of
  the property of charge.
• Coulombs Law

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D1.13(b) From the construction, it is
evident that the resultant force is directed away
from the center of the square. The magnitude of
this resultant force is given by
Q2/4pe0(2a2)
Q2/4pe0(4a2)
Q2/4pe0(2a2)
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• Electric Field Intensity, E
• is defined as the force per unit charge
  experienced by a small test charge when placed in
  the region of the field.
• Thus
• Units

Sources Charges Time-varying magnetic field
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Electric Field of a Point Charge
(Coulombs Law)
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Constant magnitude surfaces are spheres centered
at Q. Direction lines are radial lines emanating
from Q.
E due to charge distributions (a) Collection of
point charges
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Ex.
Electron (charge e and mass m) is displaced from
the origin by D (ltlt d) in the x-direction and
released from rest at t 0. We wish to obtain
differential equation for the motion of the
electron and its solution.
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• For any displacement x,
• is directed toward the origin,
• and

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• The differential equation for the motion of the
  electron is
• Solution is given by

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• Using initial conditions and
  at t 0, we obtain
• which represents simple harmonic motion about the
  origin with period

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• (b) Line Charges
• Line charge
• density, rL (C/m)
• (c) Surface Charges
• Surface charge
• density, rS (C/m2)
• (d) Volume Charges
• Volume charge
• density, r (C/m3)

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• Ex. Finitely-Long Line Charge

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• Infinite Plane Sheet of Charge
• of Uniform Surface Charge Density

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• D1.16
• Given

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Solving, we obtain
(b)
(a)
(d)
(c)