1. Electric Potential, Potential Energy

2. Work and Potential Energy
In Physics 1: W = F * d = ΔPE + ΔKE
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?+
2μC 1m

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

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.
ΔEPE = -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 -
3μC -
0.5m
0.5m
0.5m -
3μC

7. Electric Potential (voltage)
Electric Potential is the Electric Potential Energy divided by the magnitude of the charge. (sound familiar?)
ΔV = ΔEPE/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 +
2μC X +
1.5m
1.5m

9. Other than infinity where is the voltage zero?
3μC -
2μC + 3m