The herald., 1897-06-06
great difference of potential is converted

great difference of potential is converted
into large current of comparatively
small difference of potential Differ
ence of potential is term USED to denote
that portion of electro-motive force,
which exists between any two points
in circuit 1t may be determined from
the quantity of electricity which flows
per second through a given circuit. The
electric potential is the power of doin 3
electric work)
At the San Gabriel station there is a
large current of comparatively small
difference of potential. 1t is fed into
step-up transformers and converted in
to small current Of comparatively great
difference of potential. In this form it
is ready to be sent to Los Angeles over
ordinary long-distance wires and it is
so carried to the Los Angeles station-a
small, but highly concentrated pack
age, so to speak.
CHANGING IT BACK
But the electric goods are not ready for
customers in this highly concentrated
form. What is wanted is the original
form, "a large current of comparatively
small difference of potential" So here
the step-down transformers are brought
into use, and then the electricity is ready
to be placed on sale. in quantities to
suit. How nicely it fits in with the plan
of alice in Wonderland"
A 1000-volt current is changed, say to
an II ,000-volt current for purposes of
transmission and then changed back to
it's original form.
Let us see if the term difference of
potential cannot be explained in lang
uage more ineligible to the lay reader.
Suppose A represents receptacle full
water. 1t is desired to transfer that
water to b, a.receptacle Of the same size
some distance away in a given time. 1t
can be done in two ways. The water
may be allowed to escape in large vol
ume with slow current, or it can be
sent in a swift current of small size In
either case the same result would be
achieved The stream Of water between
the two receptacles is the wire. The vol
ume, or bulk, Of water is the volume, o.
bulk, of electricity. AS explained before,
to transmit the large volume of electric
ity with a slow current would require a
large wire. too expensive to be practical
BILE. So the electricity is changed to a
small volume sent at a rapid rate
L IC diotl iS dOilG ny iUcdIS VI
switchboard giving the reqired volt
age to each customer. Thus, one trans
former may deliver current at 115 volts
to commercial incandescent circuits
Another may deliver current at 1000
volts, for operating power circuits
through the use of induction motors
A third may deliver current at 5000 volts
for outlying districts
AN INDUCTION COIL
Now, of what is a transformer COM
posed? What does it look like? 1t con-
sists of an inverted induction coil, in
which the primary wire is long and thin
and consequently has many turns, as
compared with thesecondary wire, which
is short, thick and has few turns. Can
induction coil is an apparatus consist
ing of two parallel coils of insulated
wire, employed for the production of
currents by mutual induction)
SOME DEFINITIONS
A current Of 10 amperes Gan ampere
is the practical unit of electric current.
1t is such current as would pass with
an electro-motive force of one volt
through a circuit whose resistance is
equal to one ohm.) at 1000 volts, when
passed into converter the number of
whose turns (of wire) in the primary
is twenty times the number in the Sec