The silver state news. [volume] (Winnemucca, Nev.) 1907-1909, 1909-01-09

netic lines emerge; its south pole is
the face into which they re-enter.
The intensity of the magnetic held
is increased either by increasing Inc
strength of the current or by increasing
the number of loops, that is, by WING
ing the wire in the form of a coli OF
helix. A coil of this kind through
which a current is passing possesses
polarity and behaves like a magnet.
Such a coil is often called a solenold.
If a core of soft iron be inserted IN
the solenoid, the poles will be found TO
be enormously stronger than before.
This constitutes an eleetro-mageh''
Electro magnets form an essential part
of nearly every electrical instrument.
A current flowing continuously IN
one direction is called a direct or one
way current. If it periodically reverses
its direction, it is called an alternating
or two-way current. An electric cur
rent behaves as if it possessed inertia
in that it is unable to start or stop IN
simultaneously. This electric inertia is
called inductive reactance or self-induc-
tion. When a current is starting the
strength of the magnetic field about 1t
increases until the current has attained
full strength after which it remains
constant as long as the strength of the
current remains constant. When the
current is stopped the strength of the
magnetic field decreases as the current
decreases.
A change in the strength of the
magnetic field of force will induce a
current in a closed circuit placed in the
field. An alternating current which IS
continuously starting and stopping and
changing its strength between stars
and stops is able to induce an alternat
ing current in a closed circuit placed
near it. This is the added property
that an alternating current possesses
that a direct current does not possess
1t marks the great distinction between
them.
Two years after Oersted's great ex
pertinent had shown that magnetism
was induced by ar electric current,
Faraday in a series of brilliant expert
ments demonstrated that a secondary
current of electricity could be induced
in a closed circuit by a primary circuit
carrying an alternating current. And
shortly after 0S3S), Prof. Henry
fonud that if the primary be wound
with fine wire and the secondary wound
with heavy wire, ga quantity current
can be induced from one of intensity
e. l., a large current with low voltage
can be induced from a small current or
high voltage. This principle is made
use of in the device called a transform
err. Here the small current at high
pressure from the mains induces a large
current at low pressure to be conduct
ed into the houses for lighting lamps,
etc.
The number of times per second that
an alternating current makes a com-
plete change of direction, that is, the
number of cycles per second, is calico
its frequency. Commercial alternating
currents are generally called low fro
quency currents. Their frequency is
seldom greater than 100 cycles per sec
ond. A high frequency current is one
in which the frequency is numbered in
millions. These high frequency cur
rents have markedly different effects
from the low frequency currents. 1t
appears that the very rapid to-and-fro
movements of the electrons in q high
frequency current cause a wave in the
ether just as the vibrating of the prong
of a tuning fork creates a wave IN
the air. The ether waves produced IN
this way, may be used in wireless
telegraphy.
In every electric circuit there is
found a resistance analogous to friction
offered to the passage of the electricity.
A force that can it against this
resistance is called an electro motive
force. 1t does not "~create' electricity
any more than a pump creates water.
Water lifted by some force above the
general level is said to have "head.''
In flowing back to the general level, it
is able to do work. Electricity, i'm
pressed by some electro-motive force,
is said to nave potential" Currents
flow from a place of high potential to
a place of low potential. In doing 50,
they are able to do work. Electricity
is not used up" in doing work. just
as there is the same amount of water
in the stream after it has passed a
turbine wheel as before, so there is the
same amount of electricity in the cur
rent after it has passed an incandes
cent lamp as before. When electricity
does work it merely loses some Of its