Fig. 12. STEEL YARD AMMETER.
29 STANDARD ELECTRICAL DICTIONARY.
Ammunition Hoist, Electric.
An apparatus for use on ships for hoisting ammunition to the guns by an
electric elevator. The characteristic feature of it is that a constant
motion of the switch or handle is required to keep it in action. If the
operator is shot so as to be incapacitated from taking charge of the
switch, the hoist stops until another is assigned to it.
Amperage.
Current intensity expressed in amperes, as an amperage of ten amperes.
Ampere.
The practical unit of electric current strength. It is the measure of
the current produced by an electro-motive force of one volt through a
resistance of one ohm. In electric quantity it is the rate of one
coulomb per second. It is one-tenth the absolute C. G. S. unit of
current strength. Its best analogy is derived from water. Assuming the
electric current to be represented by a current of water, the pressure,
head, or descent producing such current would be the electro-motive
force. The current might be measured in gallons (or other unit) passed
per second. In the analogy these gallons would be coulombs. But it might
be measured by reference to a standard stream, as for instance, the
stream which would pass through a hole an inch square under a given
head, say six inches of water. This unit is the miner's inch, and is the
exact analogy of the ampere. A current of water may flow at the rate of
so many miner's inches, just as a current of electricity may flow at the
rate of so many amperes. In neither case it will be noted is there any
reference to time. "An ampere per second" is a redundant expression, and
means no more than "an ampere"; an "ampere-second," on the other hand,
is a coulomb. The number of coulombs passed per second gives the amperes
of current.
For value of ampere, see Coulomb.
[Transcriber's note: The SI definition of an ampere: A current in two
straight parallel conductors of infinite length and negligible
cross-section, 1 metre apart in vacuum, would produce a force equal to
2E-7 newton per metre of length.]
Fig. 13. THE MINER'S INCH AS AN ANALOGY FOR THE AMPERE.
30 STANDARD ELECTRICAL DICTIONARY.
Ampere, Arc.
A conductor bent into the arc of a circle, and employed in measuring the
electric current by the electric balance.
Ampere-currents.
The currents assumed to be the cause of magnetism. (See Magnetism,
Ampere's Theory of.)
Ampere-feet.
The product of amperes of current by the length, in feet, of a conductor
passing such current. It may be in empiric calculations of dynamo or
motor construction, but is little used. One ampere-foot is a current of
one ampere passing through one foot length of a conductor, or one-tenth
ampere through ten feet, and so on.
Ampere-hour.
The quantity of electricity passed by a current of one ampere in one
hour. It is used by electric power and lighting companies as the unit of
energy supplied by them, because they maintain a constant potential
difference in their leads, so that only the amperes and hours need
measuring or recording to give the energy, viz. : volt-ampere-hours.
The same unit is applied to batteries to indicate their potential
energy, because they also are assumed to be of constant voltage or
electro-motive force.
Ampere-meters.
The product of amperes of current by the length, in meters, of a
conductor carrying such current. One ampere-meter is a current of one
ampere passing through one meter of a conductor.
The term must not be confused with the identically spelled Ampere-meter,
a synonym for Ammeter.
Ampere-minute.
The quantity of electricity passed by a current of one ampere in one
minute; sixty coulombs.
Ampere Ring.
A conductor forming a ring or circle used in electric balances for
measuring currents. (See Balance, Ampere.)
Ampere-second.
The quantity of electricity passed by a current of one ampere in one
second; the coulomb, q. v.
Amperes, Lost.
In a shunt or compound-wound dynamo, part of the total amperes of
current produced in the armature coils go through the shunt, and hence,
do not appear in the outer circuit. S. P. Thompson has proposed the term
"lost amperes" for this portion of the current.
Ampere's Memoria Technica.
An expression of the effect of a current on a magnetic needle. If we
imagine the observer in the line of the current and facing the magnetic
needle, the current entering by his feet and leaving by his head, the
north pole is deflected to his left.
31 STANDARD ELECTRICAL DICTIONARY.
Ampere-turns.
The amperes of current supplied to a magnet coil multiplied by the
number of turns the current makes in the coil. If the coil is wound two
or three in parallel, the virtual turns by which the amperes are
multiplied are one-half or one-third the actual turns of wire.
Synonym--Ampere Windings.
Ampere-turns, Primary.
The ampere-turns in the primary coil of an induction coil or
transformer.
Ampere-turns, Secondary.
The ampere-turns in the secondary coil of an induction coil or
transformer.
Amplitude of Waves.
Waves are distinguished by length and amplitude. The latter, in the case
of transverse waves, such as those of water and of the ether, correspond
with and measure the height from lowest to highest point, or from valley
to summit of the waves in question. In the case of longitudinal waves,
such as those of the air, due to sounding bodies, the ratio of degree of
rarefaction to degree of condensation existing in the system is the
amplitude. The latter can be graphically represented by a sinuous line,
such as would represent the section of a transverse wave. Ether waves
are produced by heated bodies and by electro-magnetic impulses, as in
the discharge of the Leyden jar.
The amplitude of a wave, other things being equal, is the measure of its
intensity. Thus, the louder a sound the greater is the amplitude of the
system of waves to which it is due. The same applies to ether waves,
whether they are perceived in the electro-magnetic, light, or
heat-giving modification. As the amplitude of ether waves cannot be
accurately known, amplitude is a relative term and is not stated
generally in any absolute unit.
Analogous Pole.
One of the elements of a pyro-electric crystalline substance, such as
tourmaline. When heated, such bodies acquire electrical properties. If
of such crystalline form that they are differently modified at the ends
of their crystalline axis, by hemihedral modifications, the ends may be
differently affected. One end may show positive electricity when the
temperature is rising, and negative when falling. Such end is then
called the analogous pole. The opposite end presents, in such cases, the
opposite phenomena; becoming negative when the temperature is rising,
and becoming positive when it is falling; such end is called the
antilogous pole.
Analysis.
The determination of the elements of a case. It may be chemical, and
consist in finding what a substance consists of; it may be mathematical,
and consist in determining the unknown quantities in a problem; or it
may belong to other branches of science. The term has a very extended
application. Where the constituents are only determined in kind it is
called qualitative analysis; where their quantity or percentage is
ascertained it is called quantitative analysis.
32 STANDARD ELECTRICAL DICTIONARY.
Analysis, Electric.
Chemical analysis by electrolytic methods. (See Electrolytic Analysis.)
Analyzer, Electric.
An apparatus used in investigations on electric ether waves. It consists
of a series of parallel metallic wires. When the electric waves have
been polarized, the analyzer will only permit them to go through it
intact, when the plane of vibration of the waves is parallel to its
wires.
Anelectrics.
(a) Bodies which do not become electrified by friction; a term
introduced by Gilbert, now little used, as all bodies develop
electricity under proper conditions by contact action; the reverse of
idioelectrtics.
(b) Also a conductor of electricity, the reverse of a dielectric, q. v.
(See Conductor.)
It will be seen that Gilbert's anelectrics were, after all, the same as
the modern anelectrics, i.e., conductors.
Anelectrotonus.
A term used in medical electricity or electro-therapeutics to indicate
the deceased functional activity induced in a nerve by the proximity of
the anode of an active electric circuit completed through the nerve. The
converse of Kathelectrotonus.
Angle of Declination.
The angle of error of the magnetic needle or compass, measuring the
extent of its deviation from the meridian in any locality. It is the
angle between the plane of the magnetic axis of a magnetic needle free
to take its natural position, and the geographical meridian, the needle
being counterpoised if necessary, so as to hold an absolutely horizontal
position. The deviation is expressed as being east or west, referring
always to the north pole. (See Magnetic Elements.)
Synonym--Variation of the Compass.
[Transcriber's note: See Agonic Line.]
Angle of the Polar Span.
In a dynamo or motor the angle subtended by the portion of a pole piece
facing the armature, such angle being referred to the centre of the
cross-section of the armature as its centre.
33 STANDARD ELECTRICAL DICTIONARY.
Angular Velocity.
The velocity of a body moving in a circular path, measured with
reference to the angle it passes over in one second multiplied by the
radius and divided by the time. A unit angle is taken (57°.29578 =
57° 17' 44".8 nearly) such that it is subtended by a portion of the
circumference equal in length to the radius. Hence, the circumference,
which is 360°, is equal to 2*PI*unit angle, PI being equal to 3.1416--.
"Unit angular velocity" is such as would in a circle of radius = 1
represent a path = 1, traversed in unit time = 1 second. If the radius
is r and the angle passed over is theta, the distance is proportional to
r*theta; if this distance is traversed in t seconds the angular velocity
is theta / t. The angular velocity, if it is multiplied by r, theta
expressing a distance, will give the linear velocity. The dimensions of
angular velocity are an angle (= arc / radius) / a Time = (L/L)/T =
(T^-1).
The velocity expressed by the rate of an arc of a circle of unit radius,
which arc subtends an angle of 57° 17' 44".8, such arc being traversed
in unit time, is unit angular velocity.
Animal Electricity.
Electricity, notably of high tension, generated in the animal system, in
the Torpedo, Gymnotus and Silurus. The shocks given by these fish are
sometimes very severe. The gymnotus, or electric eel, was elaborately
investigated by Faraday. It has the power of voluntarily effecting this
discharge. There is undoubtedly some electricity in all animals. The
contact of the spinal column of a recently killed frog with the lumbar
muscles produces contraction, showing electric excitement. Currents can
be obtained from nerve and muscle, or from muscle sides and muscle cut
transversely, in each case one thing representing positive and the other
negative elements of a couple.
Angle of Inclination or Dip.
The angle which the magnetic axis of a magnet, which magnet is free to
move in the vertical plane of the magnetic meridian, makes with a
horizontal line intersecting such axis. To observe it a special
instrument, the dipping compass, inclination compass, dipping needle, or
dipping circle, as it is called, is used. (See Elements, Magnetic,
--Dipping Needle,--Compass, Inclination.)
Angle of Lag.
The angle expressing the displacement of the magnetic axis of the
armature core of a dynamo in the direction of its rotation. (See Lag.)
Lag is due to the motion of the armature core.
Angle of Lead.
The angle expressing the displacement in the direction of rotation of
the armature of a dynamo which has to be given the brushes to compensate
for the lag. (See Lag.) This is positive lead. In a motor the brushes
are set the other way, giving a negative angle of lead or angle of
negative lead.
Anion.
The electro-negative element or radical of a molecule, such as oxygen,
chlorine or the radical sulphion. (See Ions.) It is the portion which
goes to the anode, q.v., in electrolytic decomposition.
34 STANDARD ELECTRICAL DICTIONARY.
Anisotropic. (adj.)
Unequal in physical properties, as in conduction and specific inductive
capacity, along various axes or directions. An anisotropic conductor is
one whose conductivity varies according to the direction of the current,
each axis of crystallization in a crystalline body marking a direction
of different conductivity. An anisotropic medium is one varying in like
manner with regard to its specific inductive capacity. In magnetism an
anisotropic substance is one having different susceptibilities to
magnetism in different directions. The term is applicable to other than
electric or magnetic subjects.
Synonym--AEolotropic.
Annealing, Electric.
Annealing by the heat produced by the passage of the electric current
through the body to be annealed. The object is clamped or otherwise
brought into a circuit, and a current strong enough to heat it to
redness, or to the desired temperature is passed through it.
Annunciator.
An apparatus for announcing a call from any place to another, as from a
living-room to an office in a hotel, or for announcing the entering of
any given room or window in a building protected by a burglar alarm.
A usual system comprises for each annunciator an electro-magnet. Its
armature is normally held away from its poles by a spring, and when in
that position a latch connected to the armature holds a little shutter.
When by a push-button or other device a current is sent through a
circuit which includes the electro-magnet the armature is attracted,
this releases the latch and the shutter drops. In dropping it displays a
number, letter or inscription which indicates the locality of the
push-button or other circuit-closing device. Often annunciators are
connected in circuit with a bell.
Fig. 14. ANNUNCIATOR.
35 STANDARD ELECTRICAL DICTIONARY.
Annunciator Clock.
A clock operating an annunciator by making contact at determined times.
Annunciator Drop.
The little shutter which is dropped by some forms of annunciators, and
whose fall discloses a number, character or inscription, indicating
whence the call was sent.
Fig. 15. DROP ANNUNCIATOR.
Fig. 16. ANNUNCIATOR DETACHING MECHANISM.
Annunciator, Gravity Drop.
An annunciator whose operations release shutters which fall by gravity.
Annunciator, Needle.
A needle annunciator is one whose indications are given by the movements
of needles, of which there is usually a separate one for each place of
calling.
Annunciator, Swinging or Pendulum.
An annunciator which gives its indications by displacing from its
vertical position a pendulum or vertically suspended arm.
36 STANDARD ELECTRICAL DICTIONARY.
Anodal Diffusion.
A term in electro-therapeutics; the introduction of a medicine into the
animal system by using a sponge-anode saturated with the solution of the
drug in question. On passing a current the desired result is secured by
cataphoresis, q. v.
Anode.
The positive terminal in a broken metallic or true conducting circuit;
the terminal connected to the carbon plate of a galvanic battery or to
its equivalent in case of any other generator. In general practice it is
restricted to the positive terminal in a decomposition or electrolytic
cell, such as the nickel anode in a nickel-plating bath or the anode of
platinum in a gas voltameter. It is the terminal out of or from which
the current is supposed to flow through the decomposition cell. In
electro-therapeutics the term is used simply to indicate the positive
terminal. In an electrolytic cell the electro-negative substance or
anion goes to the anode. Hence, it is the one dissolved, if either are
attacked. The nickel, copper or silver anodes of the electroplater
dissolve in use and keep up the strength of the bath. The platinum anode
in a gas voltameter is unattacked because the anion cannot act upon it
chemically.
Anodic Closure Contraction.
A physiological change in a living subject produced by the closing of
the electric current; the muscular contraction which takes place beneath
the anode applied to the surface of the body when the circuit is closed,
the kathode being applied elsewhere; it is due, presumably, to direct
action on the motor nerve. It is a term in electro-therapeutics. It is
the converse of anodic opening contraction, q. v. An abbreviation A. C.
C. is often used to designate it.
Anodic Duration Contraction.
A term in electro-therapeutics. On the opening or closing of an electric
circuit, the anode of which is placed over a muscle, a contraction is
observed (see Anodic Closure Contraction--Anodic Opening Contraction).
The above term is used to designate the duration of such contraction. An
abbreviation A. D. C. is often used to designate it.
Anodic Opening Contraction.
The converse of Anodic Closure Contraction, q. v.; it is the contraction
of living muscle beneath or near the anode where the circuit, including
such anode and the body in its course, is closed; a physiological
phenomenon observed in electro-therapeutics to which branch of science
the term belongs. An abbreviation A. O. C. is often used to designate
it.
Anodic Reactions.
A term in electro-therapeutics; the diagnosis of disease by the actions
of the tissue near the anode of a circuit.
Anti-Induction Conductor.
A conductor constructed to avoid induction effects in the conducting
element. Many kinds have been made. A tubular metal shield or envelope
which may be grounded will protect an enclosed conductor to some extent.
Or the conductor may be a double wire twisted around itself, one branch
being used for the regular and the other for the return circuit, thus
constituting a closed metallic circuit. The inductive effects are due to
interrupted or varying currents in neighboring wires and circuits. Many
anti-induction conductors have been invented and patented.
37 STANDARD ELECTRICAL DICTIONARY.
Anti-magnetic Shield.
In general terms a hollow screen of soft iron designed to protect any
mass of steel behind or enclosed by it from magnetization by any magnet
near it, such as a dynamo field magnet. This it does by concentrating
the lines of force within its own mass, so that the space within it or
enclosed by it is comparatively free from lines of force. It is often
applied to watches, and is virtually an iron case in which they are
enclosed.
Antimony.
A metal, one of the elements, atomic weight, 122:
equivalent, 40.6 and 24.4; valency, 3 and 5;
specific gravity, 6.8.
It is a conductor of electricity.
Relative resistance, compressed (silver = 1), 23.60
Specific resistance, 35.50 microhms.
Resistance of a wire,
(a) 1 foot long, weighing 1 grain, 3.418 ohms.
(b) 1 foot long, 1/1000 inch thick, 213.6 "
(c) 1 meter long, weighing 1 gram, 2.384 "
(d) 1 meter long. 1 millimeter thick, 0.4521 "
Resistance of a 1-inch cube, 13.98 microhms.
Approximate percentage resistance per degree C.
(1.8º F. at 20º C. 88º F.) 0.389 per cent.
Elcctro-chemical equivalent (hydrogen = .0105) .2560
(See Thermo-Electric Series.)
Anvil.
An intermittent contact, or "make and break" of the current is sometimes
produced by directly pressing a key down upon a metallic surface, the
two being terminals of the circuit. The surface or stud on which such
pressure is produced is called the anvil. The ordinary telegraph key,
which makes a contact by the pressure of the operator's fingers does it
by making a contact between a contact piece upon the front end of the
key and the anvil. In the induction coil the anvil is also found. Thus
in the cut representing the end of an induction coil and its circuit
breaker in which O and O' and P and P' represent the secondary circuit
terminal connections A is the core of soft iron wires, h is the anvil;
the hammer when resting upon it so as to be in contact closes the
circuit. When the current coming from the primary to the post i, passes
through the hammer and anvil h, and emerges by m, it magnetizes the
core; this attracts the hammer, which is made of or is armed with a mass
of iron. This breaks the circuit. The hammer falls at once on the anvil,
again making the circuit, and the action is repeated with great
rapidity. Hammer and anvil or key and anvil connections should be made
of platinum.