16.2. Electric Potential http://www.ck12.org
The unit of electric potential is called the volt and from the definition above we see that the volt is equivalent to
Joules
Coulomb→V=
J
C.Electric Potential Difference
Theelectric potential differenceis the difference in electric potential between two points within an electric field.
For example, a 1.5-volt battery has a potential difference of 1.5 volts (written 1.5V) between its positive and negative
terminals.
Parallel Plate Conductors: A uniform Electric Field
The equationE=krq 2 for the electric field holds for point charges or for a charge distribution that effectively acts as a
point charge. It turns out, however, that if opposite charges are placed on two parallel conducting plates, the electric
field between the plates is more or less uniform as long as the distance between the plates is much smaller than the
dimensions of the plates. The plates can be charged by connecting them to the positive and negative terminals of a
battery.
A battery contains a substance (called an electrolyte) which causes two dissimilar metals to acquire opposite charges.
The two dissimilar metals form the positive and negative terminals of the battery. If a metal plate is connected to
the positive terminal of the battery, and another metal plate is connected to the negative terminal of the battery, and
the two plates brought closely together, a parallel plate arrangement (parallel-plate conductors) can be constructed
with a uniform electric field between the plates (seen edge on) inFigure16.3. We will see later that parallel plate
conductors are also referred to as capacitors.
FIGURE 16.3
Parallel plates.Just as in the case of the battery, one of the plates of the parallel-plate conductor will be at a higher potential than
the other plate. Think, for example, of a standard AA battery with avoltagerating of 1.5V,Figure16.4.
FIGURE 16.4
Volt battery.See the link below to learn more about how a battery works.