Honolulu star-bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1912-2010, 1916-09-16

/ pressure at; any particular point. but
the difference In the pressure between
the two points 0n the citcnit where
! 1t is connected. The differefIce In
pressure, or VOLTAGE rs It Is usually
called, between any two points along
. circuit Is snIne tines an0iken OF as
/ the drop between I(eStW0 points.
The water in Die pipe lows from q
point OF higher pfesstiFe toward q
point Of lower pressure. The cleo
tricity In the electrical circuit flows
from the point of higher electrical
pressure or higher electrical level
toward Tthe. point OF lower electrical
pressure or electrical level. In the
electrical circuit the point OF higher
pressure Is usually marked with the
plus sign "a andathe one Of lower
pressure withsthe minus sign IL. The
terminal of the battery from which the
electricity flows when the battery is
Idischarging II called the positive ter
minal, while the terminal toward
which the electricity flows Is called
the negative terminal
Any point along the wire win be
positive with respect to points further
along the wire In the direction Of the
Icurrent. and negative with respect to
points along the wire opposite the
direction Of the current, Just Is the
pressure indicated BY. any gauge is
higher than the pressure indicated by
gauges connected to the pipe 1t points
| further along the pipe II the direction
Iof the water current
The reader should hare cleaflys n.
mind by this time the distinction be-
tween amperes and volts. The am
peres represent the value OF the cur
rent In the eircuit-thk IS. the num-
Der Of cOulombs Of electricity that
pass through the circuit during one
second, while the volts represent the
pressure causing this current or
movement of electricity.
Resistance TO Flow 81 Electricity
It is possible. In both the water and
electrical circuit to have q pressure
acting In the circuit when there Is no
current It is perfectly plain that AZ
the path OF the water be blocked or
interrupted by closing valve in the
pine there will be no current Of water.
although there may be 2 high pressure
produced by the pump II the path IN.
which the electricity moves Is blocked
lcr Interrupted by opening q switch or
cutting the wire. there. will be no cur
rent in the circuit. although the pres
sure may be high.
The currents of water and electric
lfty are. therefore, dependent upon
something besides the pressure This
something which opposes the flow OF
water in the water circuit Is called
the resistance of the circuit The re-
ststance Of an electrical circuit siTnnlv
Imposes the free flow Of electricity
through the circuit Yet the resist
ance does in no way tend to cause the
electricity to flow in the direction OPP
posite to that in which II Is flowing.
II YOU rush AGAINST tie wall of a
building, the wall pnDoses the action
of your force. yet the wall will not
rpsh Won backward when you stop
showing. r
The greater the resistance of an
electrical circuit the less the current
a certain pressure will produce and
the smaller the resistance OF the cir
cult the greater the current a certain
pressure win produce.
There Is no unit in which the resist
ance offered by pipe may be meas
ured The resistance Of an electrical
circuit is measured In unit called
the ohm. a circuit Is said to have
a resistance Of one ohm. where an
electrical pressure Of one volt will
produce a current In the circuit Of one
arnpefe.
When current OF water is tn be
produced in a pine the one thing
above all others which must be pres.