Electric Fields ch 26

1. Electric Fields ch 26 Electric fields of point sources AND E fields of other “common shapes”

2. Electric Fields • Electric fields of shapes include….. • 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.

3. 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.

4. 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.

5. 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