Honolulu star-bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1912-2010, 1916-12-30
go MIEST NEWS OF THE MlIQMOBlLE TRADE 60
90 AND INDUSTRY GO
(Hy Special Permission from Motor
Aqe.)


Aee.)
About 1881 Michael Faraday dis
covered that an electrical pressure
was produced in a wire that was
moved in a magnetic field when the
direction OF the motion of the wire
was such that il moved across the
imaginary lines Of force forming the
magnetic field II this wire be made a
part OF closed electrical circuit the
electrical pressure produced In the
wire will cause current OF electricity
In the circuit. Electrical pressures
produced in the above manner are
called induced pressures or induced
locomotive forces. and an electrical
current produced by an induced force
is called an induced current, and the
phenomenon is called electromagnetic
induction. In this discovery lies the
fundamental principle OF the opera.
tion of many forms of ignition, start
ing and lighting apparatus, such as
magnetos, electrical generators. In
duction coils, etc.
II wire ABB Figure - that is con-
nected In series with q galyanometer
--an exceedingly sensitive ammeter-
be moved in the magnetic field OF a
magnet, the needle will be DETECTED
from the zero position. This deflec-
tion of the galvanometer is due to
current in its winding which is pro-
duced by the induced electromotive
force in the wire that is moved in the
magnetic field.
yyho,, Ako - ,,,trz, On,
the magnetic field ceases the galvan-
ometer will show no DETECTION, which
indicates there is no current and
hence no induced electromotive force.
Hence the wires must be actually cut
ting the lines of force that are sup
posed to form the magnetic field in
order that there be an induced cleo
tromotive force produced in the wire.
II the wire were moved to the left,
as indicated by the arrow G, across
the magnetic field and the DETECTION
of the galvanometer happened to be
to the left, It VIII be found upon NOV
ing the conductor TO the right, as in
dicated by the arrow d, or in the d.
rection opposite to its motion in the
first case, that the galvanometer will
be DETECTED in the opposite direction
from the zero position
Direction Of Current
Since the direction in which the in
dicator Of galvanometer is defect
ed depends upon the direction of the
current through its winding. II is very
apparent that the direction of the cir
cult In the second case is opposite to
what it was In the first case; and.
since the current Is due to the in
duced electromotive force in the wire,
Il must also be in the opposite direc-
ton. II the motion of the wire in the
magnetic field is continuous right
and left, between the ends of the
magnet. there wifi be a current
through the galvanometer first in one
direction and then in the opposite d.
rection. and the moving part of the
galvanometer will swing to the right
and left of the zero position. The
motion Of the wire, however, may be
rapid enough so that the moving part
Of the galvanometer has not suffici-
ent time to take it's proper position
with respect to the current in the
circuit, and as result 1t remains prac.
tically at zero. the movement or de-
Election to the right or to the left
being very small.
The same results can be obtained
when the magnet is turned over and
the south pole is at the top and the