Potential, Absolute.
The absolute electrical potential at a point possesses a numerical value
and measures the tendency which the existing electric forces would have
to drive an electrified particle away from or prevent its approach to
the point, if such a particle, one unit in quantity, were brought up to
or were situated at that point. It is numerically equal to the number of
ergs of work which must be done to bring a positive unit of electricity
from a region where there is absolutely no electric force up to the
point in question. (Daniell.) Two suppositions are included in this. The
region where there is an electric force has to be and only can be at an
infinite distance from all electrified bodies. The moving of the
particle must take place without any effect upon the distribution of
electricity on other particles.
Potential, Constant.
Unchanging potential or potential difference.
The ordinary system of incandescent lighting is a constant potential
system, an unvarying potential difference being maintained between the
two leads, and the current varying according to requirements.
Potential Difference, Electric.
If of any two points the absolute potentials are determined, the
difference between such two expresses the potential difference.
Numerically it expresses the quantity of work which must be done to
remove a unit of electricity from one to the other against electric
repulsion, or the energy which would be accumulated in moving it the
other way.
A positively charged particle is driven towards the point of lower
potential. A negatively charged body is driven in the reverse direction.
Potential Difference, Electro-motive.
A difference of potential in a circuit, or in part of a circuit, which
difference produces or is capable of producing a current, or is due to
the flow of such current.
It may be expressed as the fall in potential or the electro-motive force
included between any two points on a circuit. The current in an active
circuit is due to the total electro-motive force in the circuit. This is
distributed through the circuit in proportion to the resistance of its
parts. Owing to the distribution of electro-motive force throughout a
circuit including the generator, the terminals of a generator on closed
circuit may show a difference of potential far lower than the
electro-motive force of the generator on closed circuit. Hence potential
difference in such a case has been termed available electro-motive
force.
Potential, Electric Absolute.
The mathematical expression of a property of a point in space, measuring
the tendency which existing electric forces would have to drive an
electrified unit particle away from or prevent its approach to the point
in question, according to whether the point was situated at or was at a
distance from the point in question.
Potential is not the power of doing work, although, as it is expressed
always with reference to a unit body, it is numerically equal to the
number of ergs of work which must be done in order to bring a positive
unit of electricity from a region where there is no electric
force--which is a region at an infinite distance from all electrified
bodies--up to the point in question. This includes the assumption that
there is no alteration in the general distribution of electricity on
neighboring bodies. (Daniell.)
In practice the earth is arbitrarily taken as of zero electric potential.