Impedance.
The ratio of any impressed electro-motive force to the current which it
produces in a conductor. For steady currents it is only the resistance.
For variable currents it may include besides resistance inductance and
permittance. It is the sum of all factors opposing a current, both ohmic
and spurious resistances. It is often determined and expressed as ohms.
Synonym--Apparent Resistance--Virtual Resistance.
Impedance, Oscillatory.
The counter-electro-motive force offered to an oscillatory discharge, as
that of a Leyden jar. It varies with the frequency of the discharge
current.
Synonym--Impulsive Impedance.
Impressed Electro-motive Force.
The electro-motive force expending itself in producing current induction
in a neighboring circuit.
Impulse.
(a) An electro-magnetic impulse is the impulse produced upon the
luminiferous ether by an oscillatory discharge or other varying type of
current; the impulse is supposed to be identical, except as regards
wave-length, with a light wave.
(b) An electro-motive impulse is the electro-motive force which rises so
high as to produce an impulsive or oscillatory discharge, such as that
of a Leyden jar.
Incandescence, Electric.
The heating or a conductor to red, or, more etymologically, to white
heat by the passage of an electric current. The practical conditions are
a high intensity of current and a low degree of conductance of the
conductor relatively speaking.
Inclination Map.
A map showing the locus of equal inclination or dips of the magnetic
needle. The map shows a series of lines, each one of which follows the
places at which the dip of the magnetic needle is identical. The map
changes from year to year. (See Magnetic Elements.)
Independence of Currents in Parallel Circuits.
If a number of parallel circuits of comparatively high resistance are
supplied by a single generator of comparatively low resistance, the
current passed through each one will be almost the same whether a single
one or all are connected. Under the conditions named the currents are
practically independent of each other.
[Transcriber's note: The current in each parallel branch depends on the
resistance/impedance of that branch. Only if they all have the same
impedance will the current be the same.]
Indicating Bell.
An electric bell arranged to drop a shutter or disclose in some other
way a designating number or character when rung.