Electric Potential, Potential Energy

1
Electric Potential, Potential Energy
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Work and Potential Energy

• In Physics 1 W F d ?PE ?KE
• This is only true for constant Force, since our
  force is not constant
• WAB kqq/rA kqq/rB (J)

3
How much work does the field do if we assemble
three charges from infinitely far away?
4
How much work does the field do if we assemble
three charges from infinitely far away?
3µC
-
0.5m
0.5m
0.5m
5
Electric Potential Energy

• When gravity does negative work on an object it
  gains PE, when gravity does positive work on an
  object it looses PE.
• Work done by Electric forces behave the same way.
• ?EPE -W kqq/rB kqq/rA (J)

6
What is the change in potential energy of the
bottom charge if we bring it from infinitely far
away? (assume top charges are already present)
3µC
-
0.5m
0.5m
0.5m
7
Electric Potential (voltage)

• Electric Potential is the Electric Potential
  Energy divided by the magnitude of the charge.
  (sound familiar?)
• ?V ?EPE/q kq/rB kq/rA (V)

8
What is the change in potential or voltage in
the middle of the Charges compared to infinitely
far away?
3µC
X

9
Other than infinity where is the voltage zero?
3µC