Download Activity 7: Field Lines and Coulomb`s Law

Physics E-1ax
March 3, 2015
Activity 7: Field Lines and Coulomb’s Law
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Let’s take a look at our “charges and fields” applet again, this time for a single point
charge:
http://phet.colorado.edu/en/simulation/charges-and-fields
1.
Sketch some field lines on this plot. The rules are:
•
- Lines start on (+) charges, end on (–) charges. Lines can go off to infinity.
- At any point in space, the field lines follow the direction of the electric field.
- Number of field lines on a charge is proportional to amount of charge.
- Lines cannot split or merge, and tend to stay far away from each other.
- The field is stronger where the field lines are closer together.
1 q1
The electric potential created by a charge q1 is V (r) =
. We can find (using
4πε 0 r
calculus) the electric field created by q1:
From a point charge q1, the electric field has magnitude E =
and points away from positive charges
and towards negative charges.
2.
1 q1
4πε 0 r 2
You place another charge q2 at a distance r from q1. What is the radial component of the
force (Fr) of q1 on q2?
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