Potential, Negative.
The reverse of positive potential. (See Potential, Positive.)
Potential, Positive.
In general the higher potential. Taking the assumed direction of lines
of force, they are assumed to be directed or to move from regions of
positive to regions of negative potential. The copper or carbon plate of
a voltaic battery is at positive potential compared to the zinc plate.
Potential, Unit of Electric.
The arbitrary or conventional potential--or briefly, the potential of a
point in an electric field of force--is, numerically, the number of ergs
of work necessary to bring a unit of electricity up to the point in
question from a region of nominal zero potential--i. e., from the
surface of the earth. (Daniell.) This would give the erg as the unit of
potential.
Potential, Zero.
The potential of the earth is arbitrarily taken as the zero of electric
potential.
The theoretical zero is the potential of a point infinitely distant from
all electrified bodies.
Fig. 272. DIAGRAM OF POTENTIOMETER CONNECTIONS.
Potentiometer.
An arrangement somewhat similar to the Wheatstone Bridge for determining
potential difference, or the electro-motive force of a battery. In
general principle connection is made so that the cell under trial would
send a current in one direction through the galvanometer. Another
battery is connected, and in shunt with its circuit the battery under
trial and its galvanometer are connected, but so that its current is in
opposition. By a graduated wire, like that of a meter bridge, the
potential of the main battery shunt can be varied until no current
passes. This gives the outline of the method only.