Honolulu star-bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1912-2010, 1916-12-16
ELECTROMAGNETIC is DISCUSSED
ON THE INTRJCACIES OF THE ELECT
(By Special Permission from Motor
Age.)

(By Special Permission from Motor
Age.)
II compass needle be placed near
a horizontal conductor in which there
is a current of electricity II will be
acted upon by magnetic force which
will tend to turn the needle from its
approximately rorth and south posi-
ton. The position occupied by the
compass needle when il comes to rest
will change with change in the value
OF the current IN the conductor and
also with change in the distance
between the compass needle and the
conductor. II the din ection of the
current In the conductor be reversed
and adjusted to exactly the same val
ne as before the DETECTION the
compass needle will be changed, and
IL will De DETECTED In the opposite d.
rection from its normal position to
tnat before. These experimentally
proven facts prove:
First There is a magnetic field sur
rounding a conductor in which there
Is a current of electricity.
Second-The strength of the mag
depends upon the value OF the cur
rent.
Third--The strength of the magnet
ic field produced by the current varies
with the distance from the conductor.
Folrsh-There is |. definite relation
between the direction of the magnetic
field produced ty the current and
the direction Of the current producing
the magnetic field.
Magnetism produced in this manner
by an electric current Is called electro
magnetism.
Direction Of Magnetic Field
The direction of the magnetic. field
produced by q current of electricity
may be determined in exactly the same
manner rs the direction Of magnetic
field due to q permanent magnet
namely, by determining the direction
in which the north pole of COM
pass needle will point when placed
in the field at the point where the
direction is desired. II a compass
needle be placed beneath a wire,
as shown In Figure 1, and a current
produced IN the wire from left to
right. ~ indicated by the long, straight
arrow sbove The wire, the compass
needle VIII move In the direction in
dsllfed by the two curved arrows
at the ends Of The needle. If The
compass needle be placed above The
wire 1t win be DETECTED In the oppo-
site direction. The general direction
of the magnetic field on the under
side of the wire is toward the sur
face Of the paper and directly above
the vine, and the direction of the
magnetic field is away from the sur
face of the paper.
II the compass needle be pivoted on
a horizontal axis parallel to the wire,
instead OF q vertical axis, as in Fig
ure /, its north pole will point around
the conductor IN the same direction
as the hands Of clock as you look
along the conductor N the direction Of
the current for eli positions in which
II is placed. The same results may
be obtained by placing the conductor
in a vertical position and turning the
compass needle around the conductor,
the compass needle being free to move
in q horizontal plane instead Of a
vertical plane.
II the current in the conductor is
down, as shown in Figure 2. the di-
rection Of the magnetic field about
the conductor viii be clockwise. as
indicated BY the small arrow heads on
the dotted line.
IL irok filings be sprinkled upon a
sheet of paper through which con-
ductor passes that IL carrying cur
rent, the iron filings will arrange
themselves in more or less regular.
concenrric lines when the paper is
gently Jared, as shown in Figure 8.
Determining Direction Of Magnetic
Field
There are number of simple meth