If a piece of tourmaline excited by pyro-electricity is broken, its broken ends develop new poles exactly like a magnet when broken.
The following minerals are pyro-electric: Boracite, topaz, prehnite, zinc silicate, scolezite, axenite. The following compound substances are also so: Cane sugar, sodium- ammonium racemate and pota.s.sium tartrate.
The list might be greatly extended.
The phenomenon can be ill.u.s.trated by sifting through a cotton sieve upon the excited crystal, a mixture of red lead and flowers of sulphur. By the friction of the sifting these become oppositely electrified; the sulphur adheres to the positively electrified end, and the red lead to the negatively electrified end. (See a.n.a.logous Pole-Antilogous Pole.)
Pyromagnetic Motor.
A motor driven by the alternation of attraction and release of an armature or other moving part, as such part or a section of it is rendered more or less paramagnetic by heat.
Thus imagine a cylinder of nickel at the end of a suspension rod, so mounted that it can swing like a pendulum. A magnet pole is placed to one side to which it is attracted. A flame is placed so as to heat it when in contact with the magnet pole. This destroys its paramagnetism and it swings away from the magnet and out of the flame. It cools, becomes paramagnetic, and as it swings back is reattracted, to be again released as it gets hot enough. This const.i.tutes a simple motor.
A rotary motor may be made on the same lines. Nickel is particularly available as losing its paramagnetic property easily.
442 STANDARD ELECTRICAL DICTIONARY.
Various motors have been constructed on this principle, but none have attained any practical importance. Owing to the low temperature at which it loses its paramagnetic properties nickel is the best metal for paramagnetic motors.
In Edison"s motor, between the pole pieces of an electro-magnet a cylinder made up of a bundle of nickel tubes is mounted, so as to be free to rotate. A screen is placed so as to close or obstruct the tubes farthest from the poles. On pa.s.sing hot air or products of combustion of a fire or gas flame through the tubes, the unscreened ones are heated most and lose their paramagnetism. The screened tubes are then attracted and the armature rotates, bringing other tubes under the screen, which is stationary. Then the attracted tubes are heated while the others cool, and a continuous rotation is the result.
Fig. 279. EDISON"S PYROMAGNETIC MOTOR.
Pyromagnetic Generator.
A current generator producing electric energy directly from thermal energy by pyromagnetism.
Edison"s pyromagnetic generator has eight electro-magnets, lying on eight radii of a circle, their poles facing inward and their yokes vertical. Only two are shown in the cut. On a horizontal iron disc are mounted eight vertical rolls of corrugated nickel representing armatures. On each armature a coil of wire, insulated from the nickel by asbestus is wound. The coils are all in series, and have eight connections with a commutator as in a drum armature. There are two main divisions to the commutator. Each connects with an insulated collecting ring, and the commutator and collecting rings are mounted on a spindle rotated by power. Below the circle of vertical coils is a horizontal screen, mounted on the spindle and rotating with it.
A source of heat, or a coal stove is directly below the machine and its hot products of combustion pa.s.s up through the coils, some of which are screened by the rotating screen. The effect is that the coils are subjecting to induction owing to the change in permeability of the nickel cores, according as they are heated, or as they cool when the screen is interposed. The two commutator segments are in constant relation to the screen, and current is collected therefrom and by the collecting rings is taken to the outside circuit.
443 STANDARD ELECTRICAL DICTIONARY.
Pyromagnetism.
The development of new magnetic properties or alteration of magnetic sensibility in a body by heat. Nickel and iron are much affected as regards their paramagnetic power by rise of temperature.
Fig. 280. PYROMAGNETIC GENERATOR.
Pyrometer, Siemens" Electric.
An instrument for measuring high temperatures by the variations in electric resistance in a platinum wire exposed to the heat which is to be measured.
Q.
Symbol for electric quant.i.ty.
Quad.
(a) A contraction for quadrant, used as the unit of inductance; the henry.
(b) A contraction for quadruplex in telegraphy.
[Transcriber"s note: A modern use of "quad" is a unit of energy equal to 1E15 (one quadrillion) BTU, or 1.055E18 joules. Global energy production in 2004 was 446 quad.]
Quadrant.
A length equal to an approximate earth quadrant, equal to 1E9 centimeters. It has been used as the name for the unit of inductance, the henry, q. v.
Synonym--Standard Quadrant.
444 STANDARD ELECTRICAL DICTIONARY.
Quadrant, Legal.
The accepted length of the quadrant of the earth, 9.978E8 instead of 1E9 centimeters; or to 9,978 kilometers instead of 10,000 kilometers.
Quadrature.
Waves or periodic motions the angle of lag of one of which, with reference to one in advance of it, is 90?, are said to be in quadrature with each other.
[Transcriber"s note: If the voltage and current of a power line are in quadrature, the power factor is zero (cos(90?) = 0) and no real power is delivered to the load.]
Qualitative.
Involving the determination only of the presence or absence of a substance or condition, without regard to quant.i.ty. Thus a compa.s.s held near a wire might determine qualitatively whether a current was pa.s.sing through the wire, but would not be sufficient to determine its quant.i.ty.
(See Quant.i.tative.)
Quality of Sound.
The distinguishing characteristic of a sound other than its pitch; the timbre.
It is due to the presence with the main or fundamental sound of other minor sounds called overtones, the fundamental note prevailing and the other ones being superimposed upon it. The human voice is very rich in overtones; the telephone reproduces these, thus giving the personal peculiarities of every voice.
Synonym--Timbre.
Quant.i.tative.
Involving the determination of quant.i.ties. Thus a simple test would indicate that a current was pa.s.sing through a wire. This would be a qualitative test. If by proper apparatus the exact intensity of the current was determined, it would be a quant.i.tative determination. (See Qualitative.)
Quant.i.ty.
This term is used to express arrangements of electrical connections for giving the largest quant.i.ty of current, as a quant.i.ty armature, meaning one wound for low resistance.