The Hattiesburg news. (Hattiesburg, Miss.) 1908-1917, 1909-07-09


Fuse-A short conductor of relative
ly high resistance and low melting
point which melts and breaks the
circuit in case the current becomes
stronger than its rated value, thus
protecting the apparatus in the cir
cult from damage. O
Generator-Any apparatus capable
of producing electric current. Usual |
ly applied to machine operated by |
mechanical power. A dynamo.
Ground-The earth when used as
an electrical conductor, Any cleo
trical connection with the earth A
which the current escapes to earth.
faultq point in circuit, through
Horse-Power-The unit of mechan-
ical pow0 One horsepower will
raise $4,000 pounds one foot in one
minute. An electrical horsepower is
TAG watts.
Incandescent Lamp-An electric
light depending for It's Illuminating
power on a filament of high resistance
which is heated white-hot by the
passage of electric current of prop
er strength.
Induction-the influence exerted
through space by magnet or cur
rent-bearing wire.
Insulator-Any material or sub
stance which will not conduct electric
current. or whose resistance is so
enormously high that practically no
current passes. Glass, dry wood, rub
Der, silk wax. shellas, ETC., are insu-
lators.
Kilowatt-One thousand watts
The unit of large electrical powers.
Ohm-The unit of electrical resist
ance. All electrical conductors offer
more or less resistance to the pass
age of current, and the amount is ex-
pressed in ohms.
Pole-The terminal of a battery or
the magnetic end of a magnet. Bat
terry poles are positive and negative;
magnet poles are north and sonth
Rectifier-A device for changing an
alternating current to a direct cur
rent.
Resistance-The quality which all
conductors have of impeding the flow
of electric current through them to a
greater or less extent. It's unit is
the ohm
Rheostat-A device containing cleo
trical conductors of considerable re-
sistance, used in a circuit for the
purpose of reducing a current which
is normally too powerful for the ap-
paratus it is intended to operate.
SelfInduction-the influence which
is exerted by the current in each turn
of wire in coil upon every neigh
boring turn of wire. This influence
is magnetic in its nature, and is the
principle upon which the choking is
constructed.
Shunt-A by-path in a circuit by
which a part of the current branches
off from the main circuit, returning
to it at another point. A shunt dy-
namo or motor has its field coils
connected as a shunt to its armature
coils; that is, the field and armature
are connected in multiple.
Static Electricity-A high potential
stationary charge of electricity which
may exist upon insulated bodies. Gel
luloid being an insulator it becomes
charged with electricity by friction.
This characteristic is sometimes re-
sponsible for the spelling of moving
picture films in the camera when pict-
ures are taken on a cold day. The
marks of the static discharges show
in the film like miniature lightning
strokes.
Thermostat-An instrument which,
when heated, closes an electric cir
cult, thus operating a signal or even
turning valve to regulate the tenn
perature of a room.
Transformer-A core of iron hold
ing two coils of wire. One coil, call
ed the primary, is connected to the
supply wires; the other coil, called
ed the primary, is connected to the
lamps or other apparatus. The current
is genearted in the secondary coil by
induction from the primary. The volt
age of the secondary bears the same
relation to that of the primary that
the number of turns of wire in the
secondary coil bears to the number in
the primary. Used with alternating
currents only.
Volt-The unit of electrical force,
pressure, or potential. One volt will
! force one ampere through a resist
ance of more than one ohm.
Voltage-The number of volts ex-
listing in any circuit or generator of
81 t-ia