Duced by rapidly revolving the armature of an electromagnet in front of the poles.
The armature of the electromagnet is normally attracted by the effect of the permanent magnet, but it is furnished with two antagonistic springs tending to throw it upwards.
A wire or fibre carrying the aluminium siphon cradle is stretched across this bridge piece, and on it is also mounted the small electromagnet, forming part of the " vibrator " arrangement with its hinged armature, to which one end of the stretched wire carrying the siphon is fastened.
In order to overcome the friction of the counting train, Ferranti ingeniously gave to the core of the electromagnet a certain amount of permanent magnetism.
The amplitude of the signals can be varied in several ways, either by a shunt across the electromagnet, or by altering the tension of the controlling springs or by altering the air gap between electromagnets and armatures.
Marconi, by giving great attention to details, improved the electromagnetic tapper, and, combining it with his improved form of sensitive tube, made a telegraphic instrument as follows: the small glass tube, containing nickel and silver filings between two silver plugs, was attached to a bone holder, and under this was arranged a small electromagnet having a vibrating armature like an electric bell carrying on it a stem and hammer.
These electric pulses were made to act on an electromagnet at the receiving station, which, in accordance with Page's discovery, gave out a sound of a pitch corresponding to the number of times it was magnetized or demagnetized per second.
Von Kowalski have patented a process wherein the arc is formed at two vertical concentric copper electrodes and rotated by an electromagnet; it is worked at Vevey, Switzerland.
For the greatest possible " lifting power " of permanent magnets this estimate is probably not very far from the truth, but it is now clearly understood that the force which can be exerted by an electromagnet, or by a pair of electromagnets with= opposite poles in contact, is only limited by the greatest value to which it is practically possible to raise the magnetizing force H.
Mag., 1894, 38, 488) used a little spiral of the pure electrolytic bismuth wire prepared by Hartmann and Braun; this was placed between the pole-pieces of an electromagnet and subjected to fields of various strengths up to nearly 39,000 units.
The armature is placed between the poles of the electromagnet, and being magnetized by the magnet m it will oscillate to the right or left under the action of the poles of the electromagnet M according as the current passes through M in one direction or the other.
One form consists of a tuning-fork electrically maintained in vibration of known period, which closes an electric contact at every vibration and sets another electromagnet in operation, which reverses a switch and moves over one terminal of the condenser from a battery to a galvanometer contact.
Page of Salem, Mass., drew attention to the sound given out by an electromagnet at the instant when the electric circuit is closed or broken, and in October of the same year he discussed, in a short article a entitled " Galvanic Music," the musical note pro- covery.
Mag., 1896, 41, 153), working with du Bois's electromagnet and using a modification of the isthmus method, succeeded in pushing the induction B up to 74,200 with H =51,600, the corresponding value of I being 1798, and of only 1.44.
The current to be measured is passed through the coils of the electromagnet, then enters the mercury disk at the centre, flows through it radially in all directions, and emerges at the periphery.
The problem of determining the magnetization of iron and other metals in the strong fields formed between the poles of an electromagnet was first attacked by J.
If the wheel be driven at such rate that the armatures move one place on in about the period of the current, then on putting on the current the electromagnet controls the rate of the wheel so that the agreement of period is exact, and the wheel settles down to move so that the electric driving forces just supply the work taken out of the wheel.
Thus he was able to secure from the Sayner Hutte in 1846 the great electromagnet which he turned to such use in his magnetic researches; thus he attached to his service his former pupil the skilful mechanic Fessel; and thus he discovered and fully availed himself of the ability of the great glass-blower Geissler.
This is obtained by causing one of them to send a series of signals from one particular key, while the operator at the other station adjusts his speed until he receives the same signal after shortcircuiting his electromagnet for ten revolutions.
His first idea seems to have been to employ the vibrations of the current in an electric circuit, produced by moving the armature of an electromagnet included in the circuit nearer to or farther from the poles of the magnet.
Through this electromagnet pass impulses of current regulated in frequency by a tuningfork contact breaker; these impulses, acting on the teeth of the iron wheel, by a series of pulls keep it in uniform rotation.
It is in fact the electromagnet and spindle of a telegraph relay with a siphon in place of the tongue.
By the movement of the wire or the movement of the plate, especially if the latter projects from the top of a second and similar piece of apparatus, an electrical contact can be established by means of which an electromagnet may ring a bell, stop a clock, or set free machinery connected with a cylinder or other surface upon which an earthquake machine may record the movement of the ground.
19, consists of an armature a, pivoted at one end h in a slot at one end N of a permanent magnet m, the other pole s of which is fixed to the yoke y of a horse-shoe electromagnet M.
The current then passes through the coils of an electromagnet, which releases the printing mechanism.
M, permanent magnet; E, electromagnet; C, diaphragm; t t,, terminals.
Such a combination constitutes an electromagnet, a valuable device by means of which a magnet can be instantly made and unmade at will.
In diameter, is laid across the poles of a horseshoe electromagnet, excited by a current of such strength as to produce in the rod a magnetizing force H =20.
The metals, which were prepared in the form of small rods, were magnetized between the poles of an electromagnet and tested with a magnetometer at temperatures of - 186° and 15°.