(a) In a magnet the north pole; the pole from which lines of force are
assumed to emerge into the air.
(b) In a current generator the pole or terminal whence the current is
assumed to issue into the outer circuit. It is the positively charged
terminal, and in the ordinary voltaic battery is the terminal connected
to the copper [...]

The terminations of the cores of field or other electro-magnets, or of
permanent magnets. These terminations are variously shaped, sometimes
being quite large compared to the core proper of the magnet.
They are calculated so as to produce a proper distribution of and
direction of the lines of force from pole to pole. As a general rule the
active field [...]

(a) In a magnet the south pole; the pole into which the lines of force
are assumed to enter from the air or outer circuit.
(b) In a current generator the pole or terminal into which the current
is assumed to flow from the external circuit. It is the negatively
charged terminal and in the ordinary voltaic battery is [...]

(a) An automatic oscillating or vibrating switch or contact-breaker
which in each movement reverses the direction of a current from a
battery or other source of current of fixed direction, as such current
goes through a conductor.
(b) A switch moved by hand which for each movement effects the above
result.

The end of a crystal of a pyroelectric substance, such as tourmaline,
which end, while increasing in temperature, becomes negatively
electrified. During reduction of its temperature the reverse effect
obtains.

The end of a crystal of a pyroelectric substance, such as tourmaline,
which end when heated become positively electrified. On reduction of
temperature the reverse effect obtains.

A proportion of the circle which represents the transverse section of
the armature space between the pole pieces of the field magnet in a
dynamo or motor; it is the proportion which is filled by the faces of
the pole pieces.

That part of the surface of a magnet whence the internal magnetic lines
emerge into the air. (S. P. Thompson.) As such lines may emerge from
virtually all parts of its surface, the polar regions are indefinite
areas, and are properly restricted to the parts whence the lines emerge
in greatest quantity.

The dielectric polarization, q. v., of a dielectric, implying the
arrangement of its molecules in chains or filaments; a term due to
Faraday. He illustrated it by placing filaments of silk in spirits of
turpentine, and introduced into the liquid two conductors. On
electrifying one and grounding (or connecting to earth) the other one,
the silk filaments arranged themselves in [...]

A voltaic cell in use becomes polarized by its negative plate
accumulating hydrogen, or other cause. This gradually gives the plate a
positive value, or goes to set up a counter-electro-motive force. The
quantity of electricity required to produce the polarization of a
battery is termed its Polarization Capacity or Capacity of Polarization.