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

Gravitational Potential Energy Higher Potential Energy Lower Potential Energy

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

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.

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.

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

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

Electric Potential Which point is at a higher electric potential?

Electric Potential Electric Field lines point to the lower potential.

Equipotential Lines Simulation of Field with Equipotential Lines http://glencoe.mcgraw-hill.com/sites/0078458137/student_view0/chapter21/electric_fields_applet.html

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.

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)

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

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

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

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.

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

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