Resinous Electricity.
Negative electricity; the electricity produced upon the surface of a
resinous body by rubbing it; such a body is shellac or sealing wax;
flannel and other substances may be used as the rubbing material. (See
Electrostatic Series.)
Resistance.
(a) The quality of an electric conductor, in virtue of which it opposes
the passage of an electric current, causing the disappearance of
electro-motive force if a current passes through it, and converting
electric energy into heat energy in the passage of a current through it.
If a current passes through a conductor of uniform resistance there is a
uniform fall of potential all along its length. If of uneven resistance
the fall in potential varies with the resistance. (See Potential, Fall
of.)
The fall of potential is thus expressed by Daniell. "In a conductor, say
a wire, along which a current is steadily and uniformly passing, there
is no internal accumulation of electricity, no density of internal
distribution; there is, on the other hand, an unequally distributed
charge of electricity on the surface of the wire, which results in a
potential diminishing within the wire from one end of the wire to the
other."
Resistance varies inversely with the cross section of a cylindrical or
prismatic conductor, in general with the average cross-section of any
conductor, and in the same sense directly with its true or average or
virtual length. It varies for different substances, and for different
conditions as of temperature and pressure for the same substance. A rise
of temperature in metals increases the resistance, in some bad
conductors a rise of temperature decreases the resistance.