Electric Potential and Electric Energy

Electric Potential and Potential Difference

We define the change in electric potential energy, PEa-PEb when a charge moves from some point b to some point a, as the negative of the work done by the electric force to move the charge from b to a.

It’s useful to define the electric potential (or simply the potential) as a potential energy per unit charge:

Units of Electric Potential 1 V = 1 J/C

Relation between Electric Potential and Electric Field

Important: this simple formula for E may be used only for uniform field!!!!

Equipotential Lines

The equipotential surface must be perpendicular to the surface.

Important: the surface of a good conductor is always an equipotential surface!!!!

The Electron Volt, a Unit of Energy One electronvolt is defined as the energy acquired by a particle carrying a charge to that of the electron (q=e) as a result of moving through a potential difference of 1 V.

Electric Potential Due to Point Charges

Work to Force Two Positive Charges Close Together What minimum work is required by an external force to bring a charge q=3.00 mC from a great distance away to a point 0.5 m from a charge Q=20mC?