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Category: Electromagnetic Theory
Type: Lecture Notes
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field, surface, field, final, cylinder, perpendicular, curved, symmetric, gaussian, master, parallel,
spherically, symmetry, distribution, inside, gauss,
field due, the surface, the cylinder, the curved, charge final, the plane, edit mas
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Description
Physics for Bioscience (II)
Transcript
Announcements
Define Flux
Electric field lines passing through a surface
Define Gaussian Surface
A closed surface
Can be imaginary (that is, does not have to coincide with any real surface)
Look for symmetry
Geometrical symmetry should simplify the calculations.
Field Due to a Spherically Symmetric Charge Distribution
Spherically Symmetric, cont.
Spherically Symmetric Distribution, final
Field Due to a Thin Spherical Shell
Use spheres as the gaussian surfaces
When r a, the charge inside the surface is Q and
E keQ / r2
When r a, the charge inside the surface is 0 and E 0
Coulomb vs. Gauss
A comparison
Field at a Distance from a Line of Charge (Gauss)
Field Due to a Line of Charge, cont.
The end view confirms the field is perpendicular to the curved surface
The field through the ends of the cylinder is 0 since the field is parallel to these surfaces
Field Due to a Line of Charge, final
Field Due to a Plane of Charge
E must be perpendicular to the plane and must have the same magnitude at all points equidistant from the plane
Choose a small cylinder whose axis is perpendicular to the plane for the gaussian surface
Field Due to a Plane of Charge, cont
E is parallel to the curved surface and there is no contribution to the surface area from this curved part of the cylinder
The flux through each end of the cylinder is EA and so the total flux is 2EA
Field Due to a Plane of Charge, final
Click to edit Master title style
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Instructor
Franco Gaspari
PHY 1040U
(Physics for the biosciences)
Introduction to Electromagnetism and Optics
Lecture 5
January 23, 2007
dy
Problem calculate
By symmetry, we can consider of the rod and multiply by 2.
Symmetry also tells us that we consider only the x component.
dy
Multiply x2
g
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L
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