Electric Potential
Describe the electric potential due to a configuration of charged objects.
- Electric potential describes the electric potential energy per unit charge at a point in space.
- The electric potential due to multiple point charges can be determined by the principle of scalar superposition of the electric potential due to each of the point charges. Relevant equation:
- The electric potential difference between two points is the change in electric potential energy per unit charge when a test charge is moved between the two points. Relevant equation:
- Electric potential difference may also result from chemical processes that cause positive and negative charges to separate, such as in a battery.
- When conductors are in electrical contact, electrons will be redistributed such that the surfaces of the conductors are at the same electric potential.
Describe the relationship between electric potential and electric field.
- The average electric field between two points in space is equal to the electric potential difference between the two points divided by the distance between the two points. Relevant equation:
- Electric field vector maps and equipotential lines are tools to describe the field produced by a charge or configuration of charges and can be used to predict the motion of charged objects in the field.
- Equipotential lines represent lines of equal electric potential in space. These lines are also referred to as isolines of electric potential.
- Isolines are perpendicular to electric field vectors. An isoline map of electric potential can be constructed from an electric field vector map, and an electric field map may be constructed from an isoline map.
- An electric field vector points in the direction of decreasing potential.
- There is no component of an electric field along an isoline.
As the methods to calculate the electric potential due to extended charges exceed the scope of the course, AP Physics 2 only expects that students calculate the electric potential of configurations of four or fewer particles (or more in situations of high symmetry).