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Electricity and Magnetism
Electric Potential (V)
The potential at a point in a field is the work done moving a unit positive charge from infinity to that point.
As with gravitational potentials, the zero of electrical potential is at infinity but electrical potentials can be positive or negative depending on whether work is done against the field or by the field.
Potential Difference Between Two Points (V)
The potential difference between two points is the work done moving a unit positive charge from one point to the other.
If the potential at point A is VA and the potential at point B is VB then the potential difference, V, between the A and B is given by
If a charge, q, is moved through a potential difference, V, we can write
The units of V are JC-1.
Potential at a distance r from a Point Charge Q
It can be shown that the potential at p is given by