Voltage, Terminal.
The voltage or potential difference at the terminals of an electric
current generator, such as a dynamo, as distinguished from the total
electro-motive force of the dynamo or generator.
In batteries the distinction is not generally made in practice; the
total electro-motive force of the battery is made the basis of
calculations.
Voltaic. adj.
This adjective is used to qualify a great many things appertaining to or
connected with current electricity. It is derived from Volta, the
inventor of the voltaic battery, and now tends to displace the term
"galvanic," formerly in general use.
Voltaic Alternatives.
A term used in electro-therapeutics or medical electricity to indicate
an alternating battery current.
Synonym--Alternative current.
Voltaic Effect.
The potential difference developed by contact of different conductors.
It is the basis of the contact theory, q. v., of electricity, although
it may be accepted as the expression for a condition of things by those
who reject the above theory. This potential difference is slight when
the conductors are separated, but it is calculated that it would be
enormous could the metals be so quickly separated as to hold each its
own charge.
Thus if a copper and a zinc plate are assumed to be in contact, really
1/20000000 centimeter or 1/50000000 inch apart, they may be treated as a
pair of condenser plates. Being so near, their density of charge, which
is a strongly bound charge, is enormous. If it were possible to separate
them without permitting any discharge, their potential would rise by the
separation, on the principle of Epinus' condenser, q. v., to such an
extent that they would spark through twenty feet of air. (See Volta's
Fundamental Experiment.)
Voltaic Electricity.
Electricity of low potential difference and large current intensity;
electricity such as produced by a voltaic battery; current or dynamic
electricity as opposed to static electricity.
Voltameter.
In general an apparatus for determining the quantity of electricity
passing through a conductor by measuring the electrolytic action it can
perform.
Voltameter, Copper.
An apparatus which may be of similar construction with the silver
voltameter (see Voltameter, Silver), but in which a copper anode and a
solution of copper sulphate are substituted for the silver anode and
silver nitrate solution. One coulomb corresponds to .329 milligram or
.005084 grain of copper deposited. It is not accepted as of as high a
standard as the silver voltameter.
The electrodes should be placed half an inch from each other. Two square
plate electrodes may conveniently be used, and not less than two square
inches on each plate should be the area per ampere of current.