Fig. 140. SERIES DYNAMO.
Dynamo, Series.
A dynamo whose armature, field winding, and external circuit are all in
series.
In such a dynamo short circuiting or lowering the resistance of the
external circuit strengthens the field, increases the electro-motive
force and current strength and may injure the winding by heating the
wire, and melting the insulation.
202 STANDARD ELECTRICAL DICTIONARY.
Dynamo, Shunt.
A dynamo whose field is wound in shunt with the external circuit. Two
leads are taken from the brushes; one goes around the field magnets to
excite them; the other is the external circuit.
In such a dynamo the lowering of resistance on the outer circuit takes
current from the field and lowers the electro-motive force of the
machine. Short circuiting has no heating effect.
Fig. 141. SHUNT DYNAMO.
Dynamo, Single Coil.
A dynamo whose field magnet is excited by a single coil. Several such
have been constructed, with different shapes of field magnet cores, in
order to obtain a proper distribution of poles.
Dynamo, Tuning Fork.
A dynamo in which the inductive or armature coils were carried at the
ends of the prongs of a gigantic tuning fork, and were there maintained
in vibration opposite the field magnets. It was invented by T. A.
Edison, but never was used.
Dynamo, Uni-polar.
A dynamo in which the rotation of a conductor effects a continuous
increase in the number of lines cut, by the device of arranging one part
of the conductor to slide on or around the magnet. (S. P. Thomson.)
Faraday's disc is the earliest machine of this type.
203 STANDARD ELECTRICAL DICTIONARY.
Dyne.
The C. G. S. or fundamental unit of force. It is the force which can
impart an acceleration of one centimeter per second to a mass of one
gram in one second. It is equal to about 1/981 the weight of a gram,
this weight varying with the latitude.
Earth.
(a) The earth is arbitrarily taken as of zero electrostatic potential.
Surfaces in such condition that their potential is unchanged when
connected to the earth are said to be of zero potential. All other
surfaces are discharged when connected to the earth, whose potential,
for the purposes of man at least, never changes.
(b) As a magnetic field of force the intensity of the earth's field is
about one-half a line of force per square centimeter.
(c) The accidental grounding of a telegraph line is termed an earth, as
a dead, total, partial, or intermittent earth, describing the extent and
character of the trouble.
[Transcriber's note: Fallen power lines can produce voltage gradients on
the earth's surface that make walking in the area dangerous, as in
hundreds of volts per foot. Lightning may be associated with substantial
changes in the static ground potential.]
Earth, Dead.
A fault, when a telegraph or other conductor is fully connected to earth
or grounded at some intermediate point.
Synonyms--Solid Earth--Total Earth.
Earth, Partial.
A fault, when a telegraph or other conductor is imperfectly connected to
earth or grounded at some intermediate point.
Earth Plate.
A plate buried in the earth to receive the ends of telegraph lines or
other circuits to give a ground, q. v. A copper plate is often used. A
connection to a water or gas main gives an excellent ground, far better
than any plate. When the plate oxidizes it is apt to introduce
resistance.
Earth Return.
The grounding of a wire of a circuit at both ends gives the circuit an
earth return.
Earth, Swinging.
A fault, when a telegraph or other conductor makes intermittent
connection with the earth. It is generally attributable to wind action
swinging the wire, whence the name.
Ebonite.
Hard vulcanized India rubber, black in color. Specific resistance in
ohms per cubic centimeter at 46º C. (115º F.): 34E15 (Ayrton); specific
inductive capacity, (air = 1): 2.56 (Wüllner); 2.76 (Schiller); 3.15
(Boltzmann). It is used in electrical apparatus for supporting members
such as pillars, and is an excellent material for frictional generation
of potential. Its black color gives it its name, and is sometimes made a
point of distinction from Vulcanite, q. v.
204 STANDARD ELECTRICAL DICTIONARY.
Economic Coefficient.
The coefficient of electric efficiency. (See Efficiency, Electric.)
Edison Effect.
A continuous discharge resulting in a true current which takes place
between a terminal of an incandescent lamp filament and a plate placed
near it. The lamp must be run at a definitely high voltage to obtain it.
Ediswan.
An abbreviation for Edison-Swan; the trade name of the incandescent lamp
used in Great Britain, and of other incandescent system apparatus.
Fig. 142. GYMNOTUS ELECTRICUS.
Eel, Electric (Gymnotus Electricus).
An eel capable of effecting the discharge of very high potential
electricity, giving painful or dangerous shocks. Its habitat is the
fresh water, in South America. Faraday investigated it and estimated its
shock as equal to that from fifteen Leyden jars, each of 1.66 square
feet of coating. (See Animal Electricity and Ray, Electric.)
Effect, Counter-inductive.
A counter-electro-motive force due to induction, and opposing a current.
Efficiency.
The relation of work done to energy absorbed. A theoretically perfect
machine would have the maximum efficiency in which the two qualities
named would be equal to each other. Expressed by a coefficient, q. v.,
the efficiency in such case would be equal to 1. If a machine produced
but half the work represented by the energy it absorbed, the rest
disappearing in wasteful expenditure, in heating the bearings, in
overcoming the resistance of the air and in other ways, its efficiency
would be expressed by the coefficient 1/2 or .5, or if one hundred was
the basis, by fifty per centum. There are a number of kinds of
efficiencies of an electric generator which are given below.
Efficiency, Commercial.
Practical efficiency of a machine, obtained by dividing the available
output of work or energy of a machine by the energy absorbed by the same
machine. Thus in a dynamo part of the energy is usefully expended in
exciting the field magnet, but this energy is not available for use in
the outer circuit, is not a part of the output, and is not part of the
dividend.
If M represents the energy absorbed, and W the useful or available
energy, the coefficient of commercial efficiency is equal to W/M. M is
made up of available, unavailable and wasted (by Foucault currents,
etc.,) energy. Calling available energy W, unavailable but utilized
energy w, and wasted energy m, the expression for the coefficient of
commercial efficiency becomes
W / ( W + w + m )
when M = W + w + m
Synonym--Net efficiency.
205 STANDARD ELECTRICAL DICTIONARY.
Efficiency, Electrical.
In a dynamo or generator the relation of total electric energy produced,
both wasted and useful or available to the useful or available
electrical energy. If we call W the useful electric and w the wasted
electric energy, the coefficient of electrical efficiency is equal to
W / ( W + w )
Synonyms--Intrinsic Efficiency--Economic Coefficient--Coefficient of
Electrical Efficiency.
Efficiency of Conversion.
In a dynamo or generator the relation of energy absorbed to total
electric energy produced. Part of the electric energy is expended in
producing the field and in other ways. Thus a generator with high
efficiency of conversion may be a very poor one, owing to the
unavailable electric energy which it produces. The coefficient of
Efficiency of Conversion is obtained by dividing the total electric
energy produced by the energy absorbed in working the dynamo. If M
represents the energy absorbed, or work done in driving the dynamo or
generator, W the useful electric, and w the wasted electrical energy,
then the coefficient of efficiency of conversion is equal to
(W + w ) / M
In the quantity M are included besides available (W) and unavailable (w)
electric energy, the totally wasted energy due to Foucault currents,
etc., calling the latter m, the above formula may be given
( W+ w ) / (W + w + m )
This coefficient may refer to the action of a converter, q. v., in the
alternating system. Synonym--Gross Efficiency.
Efficiency of Secondary Battery, Quantity.
The coefficient obtained by dividing the ampere-hours obtainable from a
secondary battery by the ampere hours required to charge it.
Efficiency of Secondary Battery, Real.
The coefficient obtained by dividing the energy obtainable from a
secondary battery by the energy absorbed in charging it. The energy is
conveniently taken in watt-hours and includes the consideration of the
spurious voltage. (See Battery, Secondary.)
206 STANDARD ELECTRICAL DICTIONARY.
Efflorescence.
The appearance of a dry salt upon the walls of a vessel containing a
solution above the normal water-line from evaporation of a liquid. It
appears in battery jars and in battery carbons, in the latter
interfering with the electrical connections, and oxidizing or rusting
them. (See Creeping.)
Effluvium, Electric.
When a gas is made to occupy the position of dielectric between two
oppositely electrified surfaces a peculiar strain or condition of the
dielectric is produced, which promotes chemical change. The condition is
termed electrical effluvium or the silent discharge. By an apparatus
specially constructed to utilize the condition large amounts of ozone
are produced.
Synonym--Silent Discharge.
Elastic Curve.
A crude expression for a curve without projections or sudden
sinuosities; such a curve as can be obtained by bending an elastic strip
of wood.
Electrepeter.
An obsolete name for a key, switch or pole changer of any kind.
Elasticity, Electric.
The phenomenon of the dielectric is described under this term. When a
potential difference is established between two parts of the dielectric,
a flow of electricity displacement current starts through the
dielectric, which current is due to the electric stress, but is
instantly arrested by what has been termed the electric elasticity of
the dielectric. This is expressed by
( electric stress ) / ( electric strain )
and in any substance is inversely proportional to the specific inductive
capacity.
Electricity.
It is impossible in the existing state of human knowledge to give a
satisfactory definition of electricity. The views of various authorities
are given here to afford a basis for arriving at the general consensus
of electricians.
We have as yet no conception of electricity apart from the electrified
body; we have no experience of its independent existence. (J. E. H.
Gordon.)
What is Electricity? We do not know, and for practical purposes it is
not necessary that we should know. (Sydney F. Walker.)
Electricity … is one of those hidden and mysterious powers of nature
which has thus become known to us through the medium of effects.
(Weale's Dictionary of Terms.)
This word Electricity is used to express more particularly the cause,
which even today remains unknown, of the phenomena that we are about to
explain. (Amédée Guillemin.)
207 STANDARD ELECTRICAL DICTIONARY.
Electricity is a powerful physical agent which manifests itself mainly
by attractions and repulsions, but also by luminous and heating effects,
by violent commotions, by chemical decompositions, and many other
phenomena. Unlike gravity, it is not inherent in bodies, but it is
evoked in them by a variety of causes … (Ganot's Physics.)
Electricity and magnetism are not forms of energy; neither are they
forms of matter. They may, perhaps, be provisionally defined as
properties or conditions of matter; but whether this matter be the
ordinary matter, or whether it be, on the other hand, that
all-pervading ether by which ordinary matter is surrounded, is a question
which has been under discussion, and which now may be fairly held to be
settled in favor of the latter view. (Daniell's Physics.)
The name used in connection with an extensive and important class of
phenomena, and usually denoting the unknown cause of the phenomena or
the science that treats of them. (Imperial Dictionary.)
Electricity. . . is the imponderable physical agent, cause, force or the
molecular movement, by which, under certain conditions, certain
phenomena, chiefly those of attraction and repulsion, . . . are
produced. (John Angell.)
It has been suggested that if anything can rightly be called
"electricity," this must be the ether itself; and that all electrical
and magnetic phenomena are simply due to changes, strains and motions in
the ether. Perhaps negative electrification. . .means an excess of
ether, and positive electrification a defect of ether, as compared with
the normal density. (W. Larden.)
Electricity is the name given to the supposed agent producing the
described condition (i. e. electrification) of bodies. (Fleeming
Jenkin.)
There are certain bodies which, when warm and dry, acquire by friction,
the property of attracting feathers, filaments of silk or indeed any
light body towards them. This property is called Electricity, and bodies
which possess it are said to be electrified. (Linnaeus Cumming.)
What electricity is it is impossible to say, but for the present it is
convenient to look upon it as a kind of invisible something which
pervades all bodies. (W. Perren Maycock.)
What is electricity? No one knows. It seems to be one manifestation of
the energy which fills the universe and which appears in a variety of
other forms, such as heat, light, magnetism, chemical affinity,
mechanical motion, etc. (Park Benjamin.)
208 STANDARD ELECTRICAL DICTIONARY.
The theory of electricity adopted throughout these lessons is, that
electricity, whatever its true nature, is one, not two; that this
Electricity, whatever it may prove to be, is not matter, and is not
energy; that it resembles both matter and energy in one respect,
however, in that it can neither be created nor destroyed. (Sylvanus P.
Thomson.)
In Physics a name denoting the cause of an important class of phenomena
of attraction and repulsion, chemical decomposition, etc., or,
collectively, these phenomena themselves. (Century Dictionary.)
A power in nature, often styled the electric fluid, exhibiting itself,
when in disturbed equilibrium or in activity, by a circuit movement, the
fact of direction in which involves polarity, or opposition of
properties in opposite directions; also, by attraction for many
substances, by a law involving attraction between substances of unlike
polarity, and repulsion between those of like; by exhibiting accumulated
polar tension when the circuit is broken; and by producing heat, light,
concussion, and often chemical changes when the circuit passes between
the poles, or through any imperfectly conducting substance or space. It
is evolved in any disturbance of molecular equilibrium, whether from a
chemical, physical, or mechanical cause. (Webster's Dictionary.)
In point of fact electricity is not a fluid at all, and only in a few of
its attributes is it at all comparable to a fluid. Let us rather
consider electricity to be a condition into which material substances
are thrown. . .(Slingo & Brooker.)
[Transcriber's note: 2008 Dictionary: Phenomena arising from the
behavior of electrons and protons caused by the attraction of particles
with opposite charges and the repulsion of particles with the same
charge.]
Electricity, Cal.
The electricity produced in the secondary of a transformer by changes of
temperature in the core. This is in addition to the regularly induced
current.
Synonym--Acheson Effect.
Electrics.
Substances developing electrification by rubbing or friction; as
Gilbert, the originator of the term, applied it, it would indicate
dielectrics. He did not know that, if insulated, any substance was one
of his "electrics." A piece of copper held by a glass handle becomes
electrified by friction.
Electrification.
The receiving or imparting an electric charge to a surface; a term
usually applied to electrostatic phenomena.
Electrization.
A term in electro-therapeutics; the subjection of the human system to
electric treatment for curative, tonic or diagnostic purposes.
Electro-biology.
The science of electricity in its relation to the living organism,
whether as electricity is developed by the organism, or as it affects
the same when applied from an external source.
209 STANDARD ELECTRICAL DICTIONARY.
Electro-capillarity.
The relations between surface tension, the potential difference and the
electrostatic capacity of fluids in contact. Although nominally in
contact such surfaces are separated by about one-twenty-millionth of a
centimeter (1/50000000 inch) ; thus a globule of mercury and water in
which it is immersed constitute an electrostatic accumulator of definite
electrostatic capacity. Again the mercury and water being in electric
connection differ in potential by contact (see Contact Theory). A
definite surface tension is also established. Any change in one of these
factors changes the other also. A current passed through the contact
surfaces will change the surface tension and hence the shape of the
mercury globule. Shaking the globule will change its shape and capacity
and produce a current. Heating will do the same. (See Electrometer,
Capillary; and Telephone, Capillary.) Mercury and water are named as
liquids in which the phenomena are most conveniently observed. They are
observable in other parallel cases.
Electro-chemical Equivalent.
The quantity of an element or compound liberated from or brought into
combination, electrolytically, by one coulomb of electricity. The
electro-chemical equivalent of hydrogen is found by experiment to be
.0000105 gram. That of any other substance is found by multiplying this
weight by its chemical equivalent referred to hydrogen, which is its
atomic or molecular weight divided by its valency. Thus the atomic
weight of oxygen is 16, its valency is 2, its equivalent is 16/2 = 8;
its electro-chemical equivalent is equal to .0000105 X 8 = .000840 gram.
Electro-chemical Series.
An arrangement of the elements in the order of their relative electrical
affinities so that each element is electro-negative to all the elements
following it, and electro-positive to the elements preceding it. The
usual series begins with oxygen as the most electro-negative and ends
with potassium as the most electro-positive element. There is, of
course, no reason why other series of compound radicals, such as
sulphion (SO4), etc., should not also be constructed. For each liquid
acting on substances a separate series of the substances acted on may be
constructed. Thus for dilute sulphuric acid the series beginning with
the negatively charged or most attacked one is zinc, amalgamated or
pure, cadmium, iron, tin, lead, aluminum, nickel, antimony, bismuth,
copper, silver, platinum. In other liquids the series is altogether
different.
Electro--chemistry.
The branch of electricity or of chemistry treating of the relations
between electric and chemical force in different compounds and
reactions. (See Electrolysis--Electrochemical series--Electro-chemical
Equivalent .)
210 STANDARD ELECTRICAL DICTIONARY.
Electro-culture.
The application of electricity to the cultivation of plants. In one
system wires are stretched or carried across the bed under the surface,
and some are connected to one pole and others to the other pole of a
galvanic battery of two or more elements. In some experiments improved
results have thus been obtained.
Another branch refers to the action of the electric arc light on
vegetation. This has an effect on vegetation varying in results.
Electrode.
(a) The terminal of an open electric circuit.
(b) The terminals of the metallic or solid conductors of an electric
circuit, immersed in an electrolytic solution.
(c) The terminals between which a voltaic arc is formed, always in
practice made of carbon, are termed electrodes.
(d) In electro-therapeutics many different electrodes are used whose
names are generally descriptive of their shape, character, or uses to
which they are to be applied. Such are aural electrodes for the ears,
and many others.
(e) The plates of a voltaic battery.
Electrode, Indifferent.
A term in electro-therapeutics. An electrode to which no therapeutic
action is attributed but which merely provides a second contact with the
body to complete the circuit through the same. The other electrode is
termed the therapeutic electrode.
Electrodes, Erb's Standards of.
Proposed standard sizes for medical electrodes as follows:
Name. Diameter.
Fine Electrode, 1/2 centimeter .2 inch
Small " 2 " .8 "
Medium " 7.5 " 3.0 "
Large " 6X2 " 2.4 X .8 "
Very large " 16x8 " 6.4 x 3.2 "
Electrodes, Non-polarizable.
In electro-therapeutics electrodes whose contact surface is virtually
porous clay saturated with zinc chloride solution. The series terminate
in amalgamated zinc ends, enclosed each in a glass tube, and closed with
clay. Contact of metal with the tissues is thus avoided.
Electrode, Therapeutic.
A term in electro-therapeutics. An electrode applied to the body for the
purpose of inducing therapeutic action, or for giving the basis for an
electric diagnosis of the case. The other electrode is applied to
complete the circuit only; it is termed the indifferent electrode.
Electro-diagnosis.
The study of the condition of a patient by the reactions which occur at
the terminals or kathode and anode of an electric circuit applied to the
person. The reactions are divided into kathodic and anodic reactions.
211 STANDARD ELECTRICAL DICTIONARY.
Electro-dynamic. adj.
The opposite of electrostatic; a qualification of phenomena due to
current electricity.
Synonym--Electro-kinetic.
Electro-dynamic Attraction and Repulsion.
The mutual attraction and repulsion exercised by currents of electricity
upon each other. The theory of the cause is based upon stress of the
luminiferous ether and upon the reaction of lines of force upon each
other. For a resumé of the theory see Induction, Electro-magnetic.
Electro-dynamics.
The laws of electricity in a state of motion; the inter-reaction of
electric currents. It is distinguished from electro-magnetic induction
as the latter refers to the production of currents by induction. The
general laws of electro-dynamics are stated under Induction,
Electro-magnetic, q. v.
Synonym--Electro-kinetics.
Fig. 143. DIAGRAM OF CONNECTIONS OF
SIEMENS' ELECTRO-DYNAMOMETER.
212 STANDARD ELECTRICAL DICTIONARY.
Electro-dynamometer, Siemens'.
An apparatus for measuring currents by the reaction between two coils,
one fixed and one movable, through which the current to be measured
passes. It is one of the oldest commercial ammeters or current
measurers. It comprises a fixed coil of a number of convolutions and a
movable coil often of only one convolution surrounding the other. The
movable coil is suspended by a filament or thread from a spiral spring.
The spring is the controlling factor. Connection is established through
mercury cups so as to bring the two coils in series. In use the spring
and filament are adjusted by turning a milled head to which they are
connected until the coils are at right angles. Then the current is
turned on and deflects the movable coil. The milled head is turned until
the deflection is overcome. The angle through which the head is turned
is proportional to the square of the current. The movable coil must in
its position at right angles to the fixed one lie at right angles to the
magnetic meridian.
Thus in the diagram, Fig. 143 A B C D is the fixed coil; E F G H is the
movable coil; S is the spiral spring attached at K to the movable coil.
The arrows show the course of the current as it goes through the coils.
Electrolier.
A fixture for supporting electric lamps; the analogue in electric
lighting of the gasolier or gas chandelier. Often both are combined, the
same fixture being piped and carrying gas burners, as well as being
wired and carrying electric lamps.
Electrolysis.
The separation of a chemical compound into its constituent parts or
elements by the action of the electric current. The compound may be
decomposed into its elements, as water into hydrogen and oxygen, or into
constituent radicals, as sodium sulphate into sodium and sulphion, which
by secondary reactions at once give sodium hydrate and sulphuric acid.
The decomposition proceeds subject to the laws of electrolysis. (See
Electrolysis, Laws of.) For decomposition to be produced there is for
each compound a minimum electro-motive force or potential difference
required. The current passes through the electrolyte or substance
undergoing decomposition entirely by Electrolytic Conduction, q. v. in
accordance with Grothüss' Hypothesis, q. v. The electrolyte therefore
must be susceptible of diffusion and must be a fluid.
The general theory holds that under the influence of a potential
difference between electrodes immersed in an electrolyte, the molecules
touching the electrodes are polarized, in the opposite sense for each
electrode. If the potential difference is sufficient the molecules will
give up one of their binary constituents to the electrode, and the other
constituent will decompose the adjoining molecule, and that one being
separated into the same two constituents will decompose its neighbor,
and so on through the mass until the other electrode is reached. This
one separates definitely the second binary constituent from the
molecules touching it.
213 STANDARD ELECTRICAL DICTIONARY.
Thus there is an exact balance preserved. Just as many molecules are
decomposed at one electrode as at the other, and the exact chain of
decomposition runs through the mass. Each compound electrolyzed develops
a binary or two-fold composition, and gives up one constituent to one
electrode and the other to the other.
