1. -Electric Potential Energy -Electric Potential Difference(Voltage)
Physics
Mrs. Coyle

2. Gravitational Potential Energy
Higher Potential Energy
Lower Potential Energy

3. Electric Potential Energy- Two Unlike Charges+
Higher Potential Energy -
Lower Potential Energy

4. Work done by an Electric Force
For a point charge, qo , in field, E:
Force from the field: F=qoE
The work done by the force to move the charge from point A to B (in the direction of the field) is: W=Fd
The object loses potential energy.

5. Change in Electric Potential Energy
DPEA->B = PEB-PEA = W
W: work done by the force F to move the charge from A to B.

6. Electric Potential Energy
Which point is at a higher electric potential energy location?

7. Electric Potential Difference (Voltage ):
-The work per unit charge required to move a charge between two positions in an electric field.
DV = W/qo q is the positive test charge
Scalar
Unit: Volt = J / C

8. Electric Potential
Which point is at a higher electric potential?

9. Electric Potential
Electric Field lines point to the lower potential.

10. Equipotential Lines Simulation of Field with Equipotential Lines

11. Electric Field Strength (Vector) in Terms of Voltage
E= V/d
Unit : V / m
N / C
Note:
-Electric Field is a vector.
-Voltage is a scalar.

12. Electric Fields Between Parallel Plates
Uniform Electric
Field of Strength:
E = V / d
d is the distance between the plates
Units: V/m =N/C=J/(Cm)

13. Force Experienced by a Test Charge Inside the Parallel Plate Field
The field is uniform so at any point in the field a test charge would feel a force
F = qE

14. Work and Energy V=Ed V=W/q0 W/q0= Ed W=q0 Ed
Unit for work: Joule or the electron volt
1 eV= qe 1V= 1.6 x 10-19C x 1V
1eV= 1.6 x 10-19J

15. Problem 1 Find: a)The field inside the plates.
b)The force felt by a 9nC charge that is situated in the field.
120N/C, 10.8 x 10 **-7 N

16. Continued
c)Draw the equipotential surfaces between the plates (hint: equally
spaced and parallel)
d)If there three equipotential
surfaces,what would be the
distance between each?
e)The work to move the charge from one equipotential to the other.

17. Continued
f)The potential difference between each equipotential surface and the negative plate.

18. Note
Zero work is done when a charge is moved along an equipotential surface.