Stopping Off.
In electroplating the prevention of deposition of the plating metal on
any desired portions of the object. It is effected by varnishing the
places where no coating is desired. An article can be plated with
silver, stopped off in any desired design, and the unvarnished portions
may then be plated with gold in another bath. Various effects can be
produced by such means.
Storage Capacity.
A term for the ampere-hours of electricity, which can be taken in
current form from a storage battery.
Storage of Electricity.
Properly speaking electricity can only be stored statically or in static
condensers, such as Leyden jars. The term has been popularly applied to
the charging of secondary or storage batteries, in which there is really
no such thing as a storage of electricity, but only a decomposition and
opposite combination brought about, which leave the battery in a
condition to give a current.
Storms, Electric.
Wide-spread magnetic and electric disturbances, involving the
disturbance of the magnetic elements and other similar phenomena. (See
Magnetic Storms.)
Strain.
The condition of a body when subjected to a stress. Various consequences
may ensue from strain in the way of disturbance of electric and other
qualities of the body strained.
Stratification Tube.
A Geissler tube, q. v., for showing the stratification of the electric
discharge through a high vacuum.
The stratifications are greatly intensified by the presence of a little
vapor of turpentine, alcohol, bisulphide of carbon and other substances.
Stray Field.
In a dynamo or motor the portion of the field whose lines of force are
not cut by the armature windings.
Stray Power.
The proportion of the energy wasted in driving a dynamo, lost through
friction and other hurtful resistances.
Streamlets, Current.
A conception bearing the same relation to an electric current that lines
of force do to a field of force; elementary currents. If evenly
distributed the current is of uniform density; if unevenly distributed,
as in alternating currents, the current density varies in different
parts of the cross section of the conductor. This evenness or unevenness
may be referred to the number of streamlets per unit of area of
cross-section.
[Transcriber's note: Streamlets per unit of area is redundant with
current density.]
Stress.
Force exercised upon a solid tending to distort it, or to produce a
strain.