The evening herald. [volume] (Albuquerque, New Mexico) 1914-1922, 1922-03-16
Fifteen Minutes of
Radio Each Day
ny
EDWARD M. DAVIS
Formerly Technical Electrical
Exaf-rt Tor q 3 0ovcrnment

The previous lesson explained
The relations between pressure, cur
rem. and resistance BY the fund
mental and vcry important OHM b
inw By maintaining n constant
pressure. or electromotive force In
an electrical circuit W. are abie 20
produce a constant current ALONG
he conducting path OF thn circuit
Two valuable methods used IN
The production Of elcctromotlNe
force for purposes o. radio COM
m%unicatipn are a. follows
tal Chemical action thy prim-
AIRY or secondary batterics.J
Obl Mechanical action Thy gem
[ orators or dynnmos)
Primary battery 4 primary Dnt-
terry rs composed 81 primary cclh
l connected together, a single nri-
mary cell consists % "a jar contnin-
lng two electrical conductors each
% different material, usually con-
strnetcd ln pate form and sup
ported without touching each other
In "a liquid known ne an elcctroiytc.
Tho chemical action OF this electro
lyte on the material In one ot the
plates sc.F up "a pressure. or differ
encc Of potential between the
I plates.
The plato which has the higher
potential De- tormcc ine poi.'. We
plate and the other the negative
plate ana Do n found that II .hese
two plates are connected hy n wire,
the difference in potential as a re-
suit Or chemical action. causer a
current Go flow from the positive
60 the negative plate along tho
wire and from the negative to shc
/ positive plate through the electro
iyfc Electrnmotive force. or pres
sure of re- primary battery depends
uuou two features. namely, the
ma,nriHlH ~ the plates n compb-
sltlun OF the ~eioctroiytr. In a pr,-
mary battery. replacement 81 the
parts De- necessary. after o time. due
CO. consumption Of material IN the
negative plate ana change In com
position uf the ~clcrtrutytc.
A common type of primary cell
consists OF 81 plate % zine and a
] plufa 81 copper suspended in a So-
1ufion of suluhuric acid In this
the sulphuric acts upon the sinc
plate. n THESE plates are connected
~cNtorually. hy e metallic conductor.
current viii flow from the copPer
to the zinc plate outside the col.
md from the zinc 20 the copper
plate through the clectrolyte.
% b. important TO remember has
IN % primary battery the plates
must De OF different materials and
the clcctrolytc must act chemically
upon one ~ the platcu IN order for
the COLI Go develop ciectromotlvc
! force
The eloCtrumutlvc force Of nri-
mary cells varies from 90 to , .
coli. nor ..1F g~auausF4uu uugu fhe
materials OF which the plates are
composed ard upon the rtrcnrtn
Or the cloctrolyte.
Another form % primary coll h
tac type known as the "Dry Cell"
which consists briefly ~ a cylinder
OF zinc containing "a rod Of carbon.
Between tho carbon rod and the
zinc cylinder isp laced r. mixture oi
crushed coke Eraphlte and man
ganosc. this mixture being Entur
1tcd with % solution Of zinc chic
ride and salammoninC Tho top ii
scaled with an nsphnltum cora.
pound and connections 10 the car
hon rod aud zinc cylinder made ok
tcrunlir. the entire cell being en-
closed Loo "a cardboard cylinder Tbs
voltage uf this cell on open curren'
ls Approximately 8 volts. Tifif
coll becomes rapidly exhausted n
required 60 furnish n continuous
current but is usef,.l IN deliverinr
small amounts OF current intermit
.en..Z
u the article 20 follow viii se
described tho construction and on
ration of co., secondary battery
which holds an important place IN
radio work