I. Set up a uniform E-field by placing two parallel plates close to each other and putting equal, but opposite, charges on them. The work done by the E-field in moving a (+) charge from point A to point B is
dWA to B = F . ds
dWA to B = q0 E .
A. Recall that the work done by a conservative force is the negative of the change in potential energy
Work = -(change in U)
WA to B = -(UB - UA)
B. The E-field is a conservative field - the work done is independent of path.
C. Here the E-field is constant. If it is not constant, we have to use
dU = -dW = - q0 E . ds
and integrate from A
Let's look at this for a point charge.
II. The electrostatic potential is the potential energy per unit charge
V = U/q
A. How is potential difference related to the E-field?
B. What is an equipotential surface?
III. What is a potential gradient?
IV. Notes on Potentials and Conductors
A. No work is needed to move a charge between two points at the same potential.
B. The surface of a conductor is a constant potential surface.
C. The electrostatic potential is constant inside a conductor and equal to its value at the surface.
D. The electron-volt is a unit of energy.