Download Electric Fields ch 26

Electric Fields ch
26
Electric fields of point sources AND
E fields of other “common shapes”
Electric Fields
 Electric fields of shapes include…..
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Point source
Really long wire
Really wide flat plane
Really spherical sphere
We’ve already discussed the point source and
that electric Field lines point in the direction
of the Force acting on a positive test charge.
Electric Fields
 For electric fields of multiple point charges, find
the electric field from each point separately and
then add them up (add as vectors with
direction)
 Electric Field Lines help visualize the e-field.
 E field lines are closer where the field is stronger
 E field lines begin on a positive charge and end on a
negative charge.
Electric Field of a continuous
charge distribution
 To find the e-field of other shapes, break the
shape up into little bitsy tiny small pieces, each
of which creates an electric field like a point
source. By summing these up (integrating) you
determine the e-field of the whole shape.
 Our book goes through the integration for a
long charged wire and a ring, plane and
sphere.(recommend reading these derivations)
 We’ll also look at one of the simulations on
archive.org to see how these derivations are
done.
Electric Field: affect on a
charge in an e-field
 A charged object in the e-field experiences a
force.
 Using E = F/q determine the Force acting on
the charged object (where q is the charge on
the object affected by the electric field E)
 Knowing F, you can determine the objects
motion using Newton’s 2nd law……F = ma