The use of the iron core renders it possible to produce a high inductive effect with a low resistance coil.
Each coil is attached to a shaft by a bell crank arrangement, and to these shafts there is secured a system of levers similar to that at the transmitter carrying the receiving pencil at the junction.
The coil is encased with firebricks and brickwork, and the smoke from the fire is carried, off by a flue in the ordinary s " way.
The recorder coil is connected mechanically to a second similar coil, which is suspended between the poles of a laminated magnet, so that the motions of the two are similar.
in the ordinary methods, a differentially wound receiving instrument was used, one coil being connected with the cable Company and the various Atlantic cables, are worked duplex on method of duplexing a cable was described by Lord Muirhead's plan.
Thus, in the case of one station and one moving railway carriage, there is a circuit consisting partly of the earth, partly of the ordinary telegraph wires at the side of the track, and partly of the circuits of the telephone receiver at one place and the secondary of the induction coil at the other, two air gaps existing in this circuit.
The antenna wire, connected to one spark ball of the induction coil, must be considered to form with the earth, connected to the other spark ball, a condenser.
In circuit with this battery was placed the secondary circuit of an induction coil, the primary circuit of which contained a telephone transmitter or microphone interrupter.
The average total inductive value of these bridges to received signals is about 40 henrys, and the coil is so arranged that the arms contain three sections or blocks of winding each, two of which are joined up to strap connexions, and the a p :?; .?
In order to avoid this sparking, every local instrument in the British Postal Telegraph Department has a " spark " coil connected across the terminals of the electromagnet.
This consists of a low resistance coil of copper wire enclosed in a laminated iron circuit similar to the magnetic shunt already de Magnetic scribed.
The lower ends of these wires are connected through the secondary coil of an oscillation transformer to an earth plate, or to a large conductor placed on or near the earth called a " balancing capacity."
In the primary circuit of the induction coil was an arrangement for rapidly intermitting the current and a key for short-circuiting this primary circuit.
When the oscillations pass through the coil they annul the hysteresis and cause a change of magnetism within the coil connected to the telephone.
Incoming currents pass from line through one coil of the relay, the key, and either the battery or battery resistance, according as whether the key is raised or depressed.
Marconi 2 imparted practical utility to this idea by tuning the two circuits together, and the arrangement now employed is as follows: - A suitable condenser C, or battery of Leyden jars, has one coating connected to one spark ball and the other through a coil of one turn with the other spark ball of a discharger S.
The signal coil is suspended by fibres and is mounted together with a fixed soft iron core on a brass plate affixed to a rack, with which a pinion operated by a milled head screw engages.
As the direction and intensity of this induced current are a function of the position of the second coil in its field, and as this position is determined by its mechanical connexion with the recorder coil, it is evident that, by a suitable choice of the electrical elements of the second coil and its alternating field, the indications on the siphon recorder can be magnified to any reasonable extent.
Rutherford examined it very carefully, and produced a magnetic detector for electric waves depending upon the power of electric oscillations in a coil to demagnetize a saturated bundle of steel wires placed in it.
galvanometer coil so that the influence of the latter causes the mirror (through the action of the magnetic needle) to be turned through a small angle in one direction or the other according to the direction of the current through the coil.
In this case a closed condenser circuit is formed with a battery of Leyden jars, an inductance coil and a spark gap, and oscillations are excited in it by discharges created across the spark gap by an induction coil or transformer.
One of these was to be connected to the earth through a telephone receiver, and the other through the secondary circuit of an induction coil in the primary circuit of which was a key.
D and spark gap, has the same natural time period of oscillation as the open circuit consisting of the antenna, secondary coil and adjustable inductance.
Direct radiators are a development of the early coil of pipe; they are made in various types and designs and are usually of cast iron.
He found, as others have dune, that if a battery, dynamo or induction coil has its terminals connected to the earth at two distant places, a system of electric currents flows between these points through the crust of the earth.
These spark balls are connected either to the secondary circuit of an induction coil I, or to that of an alternating current transformer having a secondary voltage of 20,000 to 100,000 volts.
Braun suggested in 1898 that the oscillatory discharge of a Leyden jar should be sent through the primary coil of a transformer and the secondary coil should be interposed between the antenna and an earth connexion.'
These trains are produced by pressing the key in the primary circuit of the induction coil for a longer or shorter time' and generating a long or short series of oscillatory electric sparks between the spark balls with a corresponding creation of trains of electric waves.
These two circuits are so adjusted that the closed oscillation circuit, consisting of the condenser, primary coil 1 See German Patent of F.
On one or more of the carriages of the trains were placed also insulated metallic sheets, which were in connexion through a telephone and the secondary circuit of an induction coil with the earth or rails.
ance coil of some 2000 turns of insulated copper wire, enclosed in a laminated iron circuit, and connected at intervals to a number of terminals so that equal increments of inductance may be obtained.
4); a current is sent from a battery, E, through one coil of a galvanometer, g, through a high resistance, r, through one of the wires, r, and thence back from office B (at which the wires are looped), through wire 2, through another high resistance, r', through a second coil on the galvanometer, g, and thence to earth.
Hence, by inserting a break-and-make key in the circuit of the battery, coil or dynamo, the uniform noise or hum in the telephone can be cut up into periods of long and short noises, which can be made to yield the signals of the Morse alphabet.
sending current enters an adjustable mid-point in the g coil and passes through the two halves of the winding to the ends connected to the cable and artificial line respectively.
In its course it passes through a glass tube wound over with two coils of wire; one of these is an oscillation coil through which the oscillations to be detected pass, and the other is in connexion with a telephone.
This magnet is excited by an alternating current, and the current induced in the second coil is after rectification sent through an ordinary siphon recorder.
The magnet between the poles of which the rectangular signal coil moves is built up of a number of thin flat horseshoe-shaped permanent magnets of a special quality of steel, and is provided with adjustable pole pieces.
The indicator was connected with a Ruhmkorff coil or other equivalent apparatus, designed to cause a continual succession of sparks to pass between the indicator and a metal plate situated beneath it and having a plane surface parallel to its line of motion.
38 6), the insulated wires or plates being upheld by masts, its operation is as follows: - When the key in the primary circuit of the induction coil is pressed the transmitting antenna wire is alternately charged to a high potential and discharged with the production of high frequency oscillations in it.
The oscillations are controlled either by a key inserted in the primary circuit of the exciting induction coil or transformer, or by a key cutting in and out of the primary condensers or throwing inductance in and out of the closed oscillation circuit.
Hence, when the coil at one fixed station was in action it generated high frequency alternating currents, which were propagated across the air gap between the ordinary telegraph wires and the metallic surfaces attached to one secondary terminal of the induction coil, and conveyed along the ordinary telegraph wires between station and moving train.
jars or of Leyden panes immersed in oil or some form of air condenser, and the inductance coil or primary circuit of the oscillation transformer consists of a few turns of highly insulated wire wound on a frame and immersed in oil.
Pull out your refrigerator a few feet and check the condenser coil.
Instead of inserting the sensitive tube between the receiving antenna and the earth, he inserted the primary coil of a peculiar form of oscillation transformer and connected the terminals of the tube to the secondary circuit of the transformer.
As they stopped to catch their breath, Dean noticed his rope was down to a single coil.
45) that they magnetize the part of the iron band passing through the coil.
The normal position of this coil is with its plane parallel to the lines of force of the field.
is impressed upon the circuit through the medium of the induction coil.
The conditions permit of the circulation of the alternating currents of low periodicity, which are used for operating the bells, but in respect of the battery the circuit is open until the subscriber lifts the receiver, when the hook switch, thus released, joins the transmitter with one winding of an induction coil in series across the circuit.
A cord circuit, similar in many respects, including the method .y.^9 Jr '' of operation, but equipped with condensers and impedance coils, in place of the repeating coil, is shown in fig.
But ultimately the coil becomes ventral or endogastric, in consequence of the second torsion movement then apparent.
Close to this the small renal organ (i, mediad) and the larger renal organ (k, to the right and posteriorly) are seen, also the pericardium (1) and a coil of the intestine (int) embedded in the compact liver.
It can be traced back to the intestine i near the surface of the visceral hump, and it is found that the apex of the coil formed by the hump is occupied by the liver h and the stomach v.
From this we pass to a stomach and a coil of intestine embedded in the lobes of a voluminous liver; a caecum of large size is given off near the commencement of the intestine.
In some Pulmonata (snails) the foot is extended at right angles to the visceral hump, which rises from it in the form of a coil as in Streptoneura; in others the visceral hump is not elevated, but is extended with the foot, and the shell is small or absent (slugs).
From the ovo-testis, which lies near the apex of the visceral coil, a common hermaphrodite duct ve proceeds, which receives the duct of the compact white albuminiparous gland, Ed, and then becomes much enlarged, the additional width being due to the development of glandular folds, which are regarded as forming a uterus u.
In its simplest form an electromagnetic ammeter consists of a circular coil of wire in which is pivoted eccentrically an index needle carrying at its lower end a small mass of iron.
The needle is balanced so that gravity compels it to take a certain position in which the fragment of iron occupies a position in the centre of the field of the coil where it is weakest.
When a current is passed through the coil the iron tends to move nearer to the coil of the wire where the field is stronger and so displaces the index needle over the scale.
Another type of similar instrument consists of a coil of wire having a fragment of iron wire suspended from one arm of an index needle near the mouth of a coil.
When a current is passed through the wire forming the coil, the fragment of iron is drawn more into the aperture of the coil where the field is stronger and so displaces an index needle over a scale.
In the construction of this soft-iron instrument it is essential that the fragment of iron should be as small and as well annealed as possible and not touched with tools after annealing; also it should be preferably not too elongated in shape so that it may not acquire permanent magnetization but that its magnetic condition may follow the changes of the current in the coil.
A much better form of electromagnetic ammeter can be constructed on a principle now extensively employed, which consists in pivoting in the strong field of a permanent magnet a small coil through which a part of the current to be measured is sent.
Such an instrument is called a shunted movable coil ammeter, and is represented by a type of instrument shown in fig.
- Shunted Movable Coil Ammeter, Isenthal & Co.
In this magnetic field is pivoted a small circular or rectangular coil carried in jewelled bearings, the current being passed into and out of the movable coil by fine flexible conductors.
The coil carries an index needle moving over a scale, and there is generally an iron core in the interior of the coil but fixed and independent of it.
The coil is so situated that, in its zero position when no current is passing through it, the plane of the coil is parallel to the direction of the lines of force of the field.
When a current is passed through the coil it rotates in the field and displaces the index over the scale against the control of a spiral spring like the hairspring of a watch.
In the case of ammeters intended for very small currents, the whole current can be sent through the coil, but for larger currents it is necessary to provide in the instrument a shunt which carries the main current, the movable coil being connected to the ends of this shunt so that it takes a definite small fraction of the current passed through the instrument.
Direct reading equidivisional movable coil ammeters can be made in various portable forms, and are very much employed as laboratory instruments and also as ammeters for the measurement of large electric currents in electric generating stations.
In this last case the shunt need not be contained in the instrument itself but may be at a considerable distance, wires being brought from the shunt which carries the main current to the movable coil ammeter itself, which performs the function simply of an indicator, 3.
4), which is surrounded by another coil having its axis at right angles to that of the fixed coil.
This second coil is suspended by a number of silk fibres, and to the coil is also attached a spiral spring the other end of which is fastened to a torsion head.
If then the torsion head is twisted, the suspended coil experiences a torque and is displaced through FIG.
F, Fixed coil; D, Movable coil; S, Spiral spring; T, Torsion head; MM, Mercury cups; I, Index needle.
The current can be passed into and out of the movable coil by permitting the ends of the coil to dip into two mercury cups.
If a current is passed through the fixed coil and movable coil in series with one another, the movable coil tends to displace itself so as to bring the axes of the coils, which are normally at right angles, more into the same direction.
This tendency can be resisted by giving a twist to the torsion head and so applying to the movable coil through the spring a restoring torque, which opposes the torque due to the dynamic action of the currents.
If then the torsion head is provided with an index needle, and also if the movable coil is provided with an indicating point, it is possible to measure the torsional angle through which the head must be twisted to bring the movable coil back to its zero position.
6) are such that when a current is passed through the whole of the coils in series, forces of attraction and repulsion are brought into existence which tend to force one movable coil upwards and the other movable coil downwards.
In those intended for alternating currents, the main current through the movable coil, whether consisting of one turn or more than one turn, is carried by a wire rope, of which each component strand is insulated by silk covering, to prevent the inductive action from altering the distribution of the current across the transverse section of the conductor.
To avoid the creation of induced currents, the coil frames and the base boards are constructed of slate.
In conjunction with the above receiver he employed a transmitter, which consisted of a large induction or spark coil S having its spark balls placed a few millimetres apart; one of these balls was connected to an earth FIG.
When used as a receiver for wireless telegraphy Marconi inserted the oscillation coil of this detector in between the earth and a receiving antenna, and this produced one of the most sensitive receivers yet made for wireless telegraphy.
Fleming discovered that if the filament is made incandescent by the current from an insulated battery there is a unilateral conductivity of the rarefied gas between the hot filament and the metal plate, such that if the negative terminal of the filament is connected outside the lamp through a coil in which electric oscillations are created with the platinum plate, only one half of the oscillations are permitted to pass, viz., those which carry negative electricity from the hot filament to the cooled plate through the vacuous space.
Such an oscillation valve was first used by Fleming as a receiver for wireless telegraph purposes in 1904 as follows: - In between the receiving antenna and the earth is placed the primary coil of an oscillation transformer; the secondary circuit of this transformer contains a galvanometer in series with it, and the two together are joined between the external negative terminal of the carbon filament of the above-described lamp and the insulated platinum plate.
His transmitter consists of a nearly closed oscillating circuit comprising a condenser or battery of Leyden jars, a spark gap, and the primary coil of an oscillation transformer consisting of one turn of thick wire wound on a wooden frame.
Over this primary is wound a secondary circuit of five to ten turns which has one end connected to the earth through a variable inductance coil and the other end to an antenna.
The receiving arrangement consists of an antenna which is connected to earth through the primary coil of an oscillation transformer and a variable inductance.
His proposed radiator and absorber consisted of two wing-shaped plates of copper, the transmitter plates being interrupted in the centre by a spark gap, and the receiver plates by an inductance coil from the ends of which connexions were made to a coherer.
Thus, for instance, when using an induction coil or transformer to charge a condenser, it is not generally convenient to make more than 50 discharges per second, but each of these may create a train of oscillations consisting of, say, 20 to 50 waves.
The magnet was mounted with its end carrying the coil opposite, and very close to, the centre of the piece of clock spring.
The line of circuit passed through the secondary of the induction coil I to the line, from that to the telephone T at the receiving station, 'See Journal of the Telegraph, New York, April 1877; Philadelphia Times, 9th July 1877; and Scientific American, August 181 This term was used by Wheatstone in 1827 for an acoustic apparatus intended to convert very feeble into audible sounds; see his Scientific Papers, p. 32.
Gray's and then either to earth or back to the induction coil by a return line of wire.
In some cases when a magneto-generator is employed for calling purposes the coil of the machine is automatically cut out of circuit when it is not in action, and is brought into circuit when the handle is turned by the operation of a centrifugal or other arrangement.
7, the microphone, a battery and the primary of an induction coil in a local circuit, and putting the line in circuit with the secondary of the induction coil, which acted as the transmitter.
8) a repeating coil is placed in the cord circuit, and when two subscribers are connected together the winding connected to the line of the subscriber who is talking for the time being acts as primary, and the other, which is in the line of the listening subscriber, as secondary.
A fixed weight is placed on one coil and the current is varied gradually until the balance is just in equilibrium.
Direct firing is used for the second boiling of the soap mixture; but for this superheated steam may with advantage be substituted, either applied by a steam-jacket round the pan or by a closed coil of pipe within it.
By repeated fractionations he was able to divide yttrium into distinct portions which gave different spectra when exposed in a high vacuum to the spark from an induction coil.
A wire carrying an electric current is surrounded by a magnetic field, and if the wire is bent into the form of an elongated coil or spiral, a field having certain very useful qualities is generated in the interior.
A bar of soft iron introduced into the coil is at once magnetized, the magnetism, however, disappearing almost completely as soon as the current ceases to flow.
With suitable arrangements of iron and coil and a sufficiently strong current, the intensity of the temporary magnetization may be very high, and electromagnets capable of lifting weights of several tons are in daily use in engineering works.
If the bar inserted into the coil is of hardened steel instead of iron, the magnetism will be less intense, but a larger proportion of it will be retained after the current has been cut off.
In the internal field of a long coil of wire carrying an electric current, the lines of force are, except near the ends, parallel to the axis of the coil, and it is chiefly for this reason that the field due to a coil is particularly well adapted for inductively magnetizing iron and steel.
The field strength in the interior of a long uniformly wound coil containing n turns of wire and having a length of 1 centimetres is (except near the ends) H = 41rin/l.
(4) In the middle portion of the coil the strength of the field is very nearly uniform, but towards the end it diminishes, and at the ends is reduced to one-half.
The direction of the force is parallel to the axis of the coil, and related to the direction of the current as the thrust of a corkscrew to its rotation.
If the coil has the form of a ring of mean radius r, the length will be 21rr, and the field inside the coil may be expressed as H = 2ni/r.
In certain cases, as, for instance, in an iron ring wrapped uniformly round with a coil of wire through which a current is passing, the induction is entirely within the metal; there are, consequently, no free poles, and the ring, though magnetized, constitutes a poleless magnet.
In the middle part of a rod which has a length of 400 or 500 diameters the effect of the ends is insensible; but for many experiments the condition of endlessness may be best secured by giving the metal the shape of a ring of uniform section, the magnetic field being produced by an electric current through a coil of wire evenly wound round the ring.
This extraneous influence may, however, be eliminated by surrounding the rod with a coil of wire carrying a current such as will produce in the interior a magnetic field equal and opposite to the vertical component of the earth's field.
The inner coil is supplied, through the intervening apparatus, with current from the battery of secondary cells B,; this produces the desired magnetic field inside the tube.
C is a " compensating coil " consisting of a few turns of wire through which the magnetizing current passes; it serves to neutralize the effect produced upon the magnetometer by the magnetizing coil, and its distance from the magnetometer is so adjusted that when the circuit is closed, no ferromagnetic metal being inside the magnetizing coil, the ti, magnetometer needle undergoes no deflection.
The specimen upon which an experiment is to be made generally consists of a wire having a " dimensional ratio " of at least 300 or goo; its length should be rather less than that of the magnetizing coil, in order that the field Ho, to which it is subjected, may be approximately uniform from end to end.
Various currents are then passed through the magnetizing coil, the galvanometer readings and the simultaneous magnetometer deflections being noted.
9) from F to D, while at the same time the commutator K is rapidly worked, a series of alternating currents of gradually diminishing strength being thus caused to pass through the magnetizing coil.
If the conductor consists of a coil of wire the ends of which are connected with a suitable galvanometer, the integral electromotive force due to a sudden increase or decrease of the induction through the coil displaces in the circuit a quantity of electricity Q=SBns R, where SB is the increment or decrement of induction per square centimetre, s is the area of the coil, n the number of turns of wire, and R the resistance of the circuit.
In practice it is usual to standardize or " calibrate " the galvanometer by causing a known change of induction to take place within a standard coil connected with it, and noting the corresponding deflection on the galvanometer scale.
Let s be the area of a single turn of the standard coil, n the number of its turns, and r the resistance of the circuit of which the coil forms part; and let S, N and R be the corresponding constants for a coil which is to be used in an experiment.
Then if a known change of induction SB a inside the standard coil is found to cause a throw of d scale-divisions, any change of induction SB through the experimental coil will be numerically equal to the corresponding throw D multiplied by snRBa/SNrd.
For a series of experiments made with the same coil this fraction is constant, and we may write SB = kD.
Rowland and others have used an earth coil for calibrating the galvanometer, a known change of induction through the coil being produced by turning it over in the earth's magnetic field, but for several reasons it is preferable to employ an electric current as the source of a known induction.
A primary coil of length 1, having n turns, is wound upon a cylinder made of non-conducting and non-magnetic material, and upon the middle of the primary a secondary or induction coil is closely fitted.
The sample may have the form of a closed ring, upon which are wound the induction coil and another coil for taking the magnetizing current; or it may consist of a long straight rod or wire which can be slipped into a magnetizing coil such as is used in magnetometric experiments, the induction coil being wound upon the middle of the wire.
Grassot has devised a galvanometer, or " fluxmeter," which greatly alleviates the tedious operation of taking ballistic readings.2 The instrument is of the d'Arsonval type; its coil turns in a strong uniform field, and is suspended in such a manner that torsion is practically negligible, the swings of the coil being limited by damping influences, chiefly electromagnetic. The index therefore remains almost stationary at the limit of its deflection, and the deflection is approximately the same whether the change of induction occurs suddenly or gradually.
The induction coil wound upon the ring is connected to the ballistic galvanometer G2 in series with a large permanent resistance R3.
In the same circuit is also included the induction coil E, which is used for standardizing the galvanometer; this secondary coil is represented in the diagram by three turns of wire wound over a much longer primary coil.
By means of the three-way switch C the battery current may be sent either into the primary of E, for the purpose of calibrating the galvanometer, or into the magnetizing coil of the ring under test.
Between the magnetizing coils is a small induction coil D, which is connected with a ballistic galvanometer.
The induction coil is carried upon the end of one portion of the test bar, and when this portion is suddenly drawn back the coil slips off and is pulled out of the field by an india-rubber spring.
Ewing (Magnetic Induction, § 194) has devised an arrangement in which two similar test bars are placed side by side; each bar is surrounded by a magnetizing coil, the two coils being connected to give opposite directions of magnetization, and each pair of ends is connected by a short massive block of soft iron having holes bored through it to fit the bars, which are clamped in position by set-screws.
If a transverse cut is made through a bar whose magnetization is I and the two ends are placed in contact, it can be shown that this force is 27r I 2 dynes per unit of area (Mascart and Joubert, Electricity and Magnetism, § 322; and if the magnetization of the bar is due to an external field H produced by a magnetizing coil or otherwise, there is an additional force equal to HI.
Thus the whole force, when the two portions of the bar are surrounded by a loosely-fitting magnetizing coil, is.
If each portion of the bar has an independent magnetizing coil wound tightly upon it, we have further to take into account the force due to, the mutual action of the two magnetizing coils, which assists.
Instead of a divided ring he employed a divided straight bar, each half of which was provided with a magnetizing coil.
The joint was surrounded by an induction coil connected with a ballistic galvanometer, an arrangement which enabled him to make an independent measurement of the induction at the moment when the two portions of the bar were separated.
The sample has the form of a thin rod, one end of which is faced true; it is slipped into the magnetizing coil from above, and when the current is turned on its smooth end adheres tightly to the surface of the yoke.
The test-piece A, surrounded by a magnetizing coil, is clamped between two soft-iron blocks B, B'.
The actual magnetizing force H is of course less than that due to the coil; the corrections required are effected automatically by the use of a set of demagnetization lines drawn on a sheet of celluloid which is supplied with the instrument.
For simplicity of calculation, the clear length of each rod between the yokes is made 12.56 (=47r) centimetres, while the coil surrounding the standard bar contains 100 turns; hence the magnetizing force due to a current of n amperes will be ion C.G.S.
The effective number of turns in the coil surrounding the test rod can be varied by means of three dial switches (for hundreds, tens and units), which also introduce compensating resistances as the number of effective turns in the coil is reduced, thus keeping the total resistance of the circuit constant.
Suppose the switches to be adjusted so that the effective number of turns in the variable coil is loo; the magnetizing forces in the two coils will then be equal, and if the test rod is of the same quality as the standard, the flow of induction will be confined entirely to the iron circuit, the two yokes will be at the same magnetic potential, and the compass needle will not be affected.
But a balance may still be obtained by altering the effective number of turns in the test coil, and thus increasing or decreasing the magnetizing force acting on the test rod, till the induction in the two rods is the same, a condition which is fulfilled when reversal of the current has no effect on the compass needle.
A small coil of fine wire, connected in series with a ballistic galvanometer, is placed in the field, with its windings perpendicular to the lines of force, and then suddenly reversed or withdrawn from the field, the integral electromotive force being twice as great in the first case as in the second.
Convenient arrangements have been introduced whereby the coil is reversed or withdrawn from the field by the action of a spring.
If a coil of insulated wire is suspended so that it is in stable equilibrium when its plane is parallel to the direction of a magnetic field, the transmission of a known electric current through the coil will cause it to be deflected through an angle which is a function of the field intensity.
An oblong coil about an inch in length is suspended from each end by thin strips of rolled German silver wire, one of which is connected with a spiral spring for regulating the tension, the other being attached to a torsion-head.
To take a reading the torsion-head is turned until an aluminium pointer attached to the coil is brought to the zero position on a small scale; the strength of the field is then proportional to the angular torsion.
The small current required is supplied to the coil from a single dry cell.
- The most generally convenient arrangement for producing such magnetic fields as are required for experimental purposes is undoubtedly a coil of wire through which an electric current can be caused to flow.
The field due to a coil can be made as nearly uniform as we please throughout a considerable space; its intensity, when the constants of the coil are known, can be calculated with ease and certainty and may be varied at will'through wide ranges, while the apparatus required is of the simplest character and can be readily constructed to suit special purposes.
But when exceptionally strong fields are desired, the use of a coil is limited by the heating effect of the magnetizing current, the quantity of heat generated per unit of time in a coil of given dimensions increasing as the square of the magnetic field produced in its interior.
Mag., 1900, 49, 329) the intensity of the highest field reached in the interior of a coil was 2200 units; this is probably the strongest field produced by a coil which has hitherto been employed in experimental work.
In 1890 some experiments in which a coil was used were made by du Bois (Phil.
Since the demagnetizing factor was o 052, the strongest field due to the coil was about 1340; but though arrangements were pro vided for cooling the apparatus by means of o ice, great difficulty was experienced owing to heating.
Upon the central neck was wound a coil consisting of one or two layers of very fine wire, which was connected with a ballistic galvanometer for measuring the induction in the iron; outside this coil, and separated from it by a small and accurately determined distance, a second coil was wound, serving to measure the induction in the iron, together with that in a small space surrounding it.
The difference of the ballastic throws taken with the two coils measured the intensity of the field in the space around the iron, and it also enabled a correction to be made for the nonferrous space between the iron neck and the centre of the thickness of'the inner coil.
Two groups of observations were recorded, one giving the induction in the inner coil and the other that in the outer coil.
From data contained in Joule's paper it may be calculated that the strongest external field Ho produced by his coil was about 126 C.G.S.
In order to meet the objection that the phenomenon might be due to electromagnetic action between the coil and the rod, Bidwell made some experiments with iron rings, and found that the length of their diameters varied under magnetization in precisely the same manner as the length of a straight rod.
The primary coil carried the magnetizing current; the secondary, which was wound inside the other, could be connected either with a ballistic galvanometer for determining the induction, or with a Wheatstone's bridge for measuring the resistance, whence the temperature was calculated.
A third platinum coil, wound non-inductively between the primary and the secondary, served to carry the current by which the ring was heated; a current of 4.6 amperes, with 16 volts across the terminals, was found sufficient to maintain the ring at a temperature of 11 50° C. In the ring itself was embedded a platinum-thermometer wire, from the resistance of which the temperature was determined.
The effect of these is beautifully illustrated by a model consisting of a number of little compass needles pivoted on sharp points and grouped near to one another upon a board, which is placed inside a large magnetizing coil.
When no current is passing through the coil and the magnetic field is of zero strength, the needles arrange themselves in positions of stable equilibrium under their mutual forces, pointing in.
As in the case of similar formations generally, they are endowed with a sensitiveness to touch which enables them to grasp and coil themselves round any suitable object which comes in their way, and thus to support the plant.
So also the principles laid down by Howard with respect to the vacuum pan hold good to-day: larger pans have been made and their heating surface has been increased, but it has been found by practice now, as it was found then, that an ordinary worm or coil 4 in.
long will be far more efficient per square foot of surface than a similar coil ioo ft.
This rod was connected with the negative pole of the generator, and was suspended from one arm of a balance-beam, while from the other end of the beam was suspended a vertical hollow iron cylinder, which could be moved into or out of a wire coil or solenoid joined as a shunt across the two carbon rods of the furnace.
Two forms of steam distillation may be distinguished: - in one the still is simply heated by a steam coil wound inside or outside the still - this is termed heating by dry steam; in the other steam is injected into the mass within the still - this is the distillation with live steam of laboratory practice.
I I consists of a cylindrical vessel having in its lower half a horizontal copper coil connected to the steam supply.
A simple method for condenser comparison is to charge the two condensers to the same voltage by a battery and then discharge them successively through a ballistic galvanometer and observe the respective " throws " or deflections of the coil or needle.
The same thing can be effected in a more perfect manner by the use of spiral or scroll drums, in which the rope is made to coil in a spiral groove upon the surface of the drum, which is formed by the frusta of two obtuse cones placed with their smaller diameters outwards.
He perceived that to coil many turns of thin wire round an inner barrel was a logical extension of the large hooped method already mentioned, and in conjunction with I.
An ohmmeter in one form consists of two pairs of coils, one pair called the series coil and the other called the shunt coil.
In making the test, the whole of the copper wires belonging to any section of the wiring and the test must be connected together at some point and then connected through the series coil of the ohmmeter with one terminal of the dynamo.
The shunt coil Sh and the series coil Se are connected together at one point, and the remaining terminals of the dynamo and shunt coil must be connected to a " good earth," which is generally the gas or water pipes w of the building.
On setting the dynamo in operation, a current passes through the shunt coil of the ohmmeter proportional to the voltage of the dynamo, and, if there is any sensible leakage through the insulator to earth, at the same time another current passes through the series coil proportional to the conductivity of the insulation of the wiring under the electromotive force used.
The two coils, the shunt and the series coil, then produce two magnetic fields, with their lines of force at right angles to one another.
The tangent of the angle of deflection 0 of this needle measured from its position, when the shunt coil is disconnected, is equal to the ratio of the voltage of the dynamo to the current through the insulator.
If the bob of the pendulum is iron, and if a coil is placed just below the centre of swing, then, if a current passes through the coil, while and only while the bob is moving towards it, the vibration is maintained.
To prevent temperature from affecting the shunt ratio, Edison joined in series with the electrolytic cell a copper coil the resistance of which increased with a rise of temperature by the same amount that the electrolyte decreased.
In order to overcome the friction of the train the field-coils are wound with an auxiliary shunt coil which supplies a driving force sufficient to overcome the friction of the counting train.
Its principle is as follows: Suppose there are two pendulum clocks, one having an ordinary pendulum and the other having a pendulum consisting of a fine coil of wire through which a current is passed proportional to the potential difference of the supply mains - in other words, a shunt current.
Below this pendulum let there be placed another coil through which passes the current to be measured; then when currents pass through these coils the pendulum of the second clock will be either accelerated or retarded relatively to the other clock, since the action of gravity is supplemented by that of an electric attraction or repulsion between the coils.
By the use of a permanent magnet instead of a shunt coil as the bob of one pendulum, the meter can be made up as an ampere-hour meter.
In proximity to the upper side of the disk is placed a coil of wire having an iron core, which is a shunt coil, the ends of the coil being connected to the terminals of the supply mains.
The current in the shunt coil lags 90 degrees behind the impressed electromotive force of the circuit to be measured; hence if the main current is in step with the potential difference of the terminals of the supply mains, which is the case when the supply is given wholly to electric lamps, then the field due to the main coil differs from that due to the shunt coil by 90 degrees.
Since the eddy currents induced in the disk are 90 degrees in phase behind the inducing field, the eddy currents produced by the main coil are in step with the magnetic field due to the shunt coil, and hence the disk is driven round by the revolution due to the action of the shunt coil upon the induced currents in the disk.
The resistance of the meter coils causes a fall in voltage down the series coil which reduces the supply pressure to the consumer.
On the other hand the resistance of the shunt coil absorbs energy which generally varies from i to 3 watts and is a loss either to the consumer or to the supply company, according to the manner in which the shunt coil is connected.
The term is generally applied to describe a particular form of electrodynamometer, consisting of a fixed coil of wire and an embracing or neighbouring coil of wire suspended so as to be movable.
The fixed coil is called the current coil, and the movable coil is called the potential coil, and each of these coils has its ends brought to separate terminals on the base of the instrument.
The movable coil of the wattmeter is normally suspended so that its axis is at right angles to that of the fixed coil, and is constrained by the torsion of a spiral spring.
Hence this power can be measured by the torsion which must be applied to the movable coil of the wattmeter to hold it in the normal position against the action of the forces tending to displace it.
In those cases in which the power - absorbing circuit is inductive, the coil of the wattmeter connected across the terminals of the power-absorbing circuit must have an exceedingly small inductance, else a considerable correction may become necessary.
The framework and case of the instrument must be completely non-metallic, else eddy currents induced in the supports will cause disturbing forces to act upon the movable coil.
The loss of the power to coil, observed in the terminals of many declining series of gastropods from the Cambrian to the present time, and the similar loss of power among Natiloidea and Ammonoidea of many genetic series, as well as the ostraean form assumed by various declining series of pelecypods and by some brachiopods, may be cited as examples.
Among the ammonites the loss of power to coil the shell is one feature of racial old age, and in others old age is accompanied by closer coiling and loss of surface ornamentation, such as spines, ribs, spirals; while in other forms an arresting of variability precedes extinction.
Tradition says that one of the Gnostic sects known as the Ophites caused a tame serpent to coil round the sacramental bread and worshipped it as the representative of the Saviour.
Electromagnetic voltmeters consist of a coil of fine wire connected to the terminals of the instrument, and the current produced in that wire by a difference of potential between the terminals creates a magnetic field proportional at any point to the strength of the current.
constant magnetic field, and in the interspace between the poles is fixed a delicately pivoted coil of wire carried in jewelled bearings.
The current is got in and out of the movable coil by means of fine flexible wires.
The movable coil has attached to it an index needle moving over a scale, and a fixed coil of high-resistance wire is included in series with the movable coil between the terminals of the instrument.
When a difference of potential is made between the terminals, a current passes through the movable coil, which then tends to place itself with its plane more at right angles to the lines of force of the field.
This motion is resisted by the torsion of a spiral spring resembling the hair-spring of a watch having one end fixed to the coil axis, and there is therefore a definite position of the needle on the scale corresponding to each potential difference between the terminals, provided it is within the range of the control.
In this case a highresistance wire is connected between the points of which the potential difference is required, and from some known fraction of this resistance wires are brought to an electrostatic voltmeter, or to a movable coil electromagnetic voltmeter, according as the voltage to be measured is alternating or continuous.
The coil of the intestine in Anodonta is similar to that of other Lamellibranchs.
Fletcher, in which the blast is heated by passing through a copper coil heated by a separate burner, is only of service when a pointed flame of a fairly high temperature is required.
The usual method of obtaining spectra by the discharges from a Ruhmkorff coil or Wimshurst machine needs no description.
With a battery of five Grove cells and a Ruhmkorff coil of medium size, a somewhat short spark, or arc, of about 5 mm.
The red spectrum is obtained at moderately low 'pressures (5 mm.) by the use of a Ruhmkorff coil without a jar or air-gap. The red lines at 7056 and 6965 (Crookes) are characteristic. The blue spectrum is best seen at a somewhat lower pressure (I mm.
The course of electrical events attending the operation of a Ruhmkorff coil being extremely complicated, special interest attaches to some experiments conducted by John Trowbridge and T.
- Round Dial Voltmeter of Kelvin Siphon Recorder, dead beat moving coil type, with front removed.
A current of great electromotive force (intensity or voltage) passed through the coil D, induces, by means of the core and frame, a current of enormous quantity (volume or amperage), but very small electromotive force, in the metal in the trough.
The limbs of the U are further twisted together in a looser or tighter coil, the axis of which may be traversed by a "spindle" muscle arising from the posterior end of the body.
Attached to the pendulum is a coil of fine wire which moves in the field of a pair of magnets.
The currents induced in the coil are led to a dead-beat D'Arsonval galvanometer having the same natural period of vibration as the pendulum.
This zoological group includes Gordian worms which are found swimming in an undulatory manner or coiling round water-weeds in ponds and puddles, or knotted together in an apparently inextricable coil.
The Platinoid Coil Was Insulated From The Water By Shellac Varnish.
When the two metal surfaces are connected for a short time with the terminals of some source of electromotive force, such as an electric machine, an induction coil or a voltaic battery, electric energy is stored up in the condenser in the form of electric strain in the glass, and can be recovered again in the form of an electric discharge.
Abandoning the long and somewhat heavy magnetic needles that had been used up to that date in galvanometers, he attached to the back of a very small mirror made of microscopic glass a fragment of magnetized watch-spring, and suspended the mirror and needle by means of a cocoon fibre in the centre of a coil of insulated wire.
The discovery of electric-current induction also led to the production of the induction coil, improved and brought to its present perfection by W.
In this new form of bobbin, the armature consisted of a ring of iron wire wound over with an endless coil of wire and connected to a commutator consisting of copper bars insulated from one another.
Such an arrangement constitutes in effect a condenser, and when the two plates respectively are connected to the secondary terminals of an induction coil in operation, the plates are rapidly and alternately charged, and discharged across the spark gap with electrical oscillations (see Electrokinetics).
Geissler (1815-1879) containing air, carbonic acid, hydrogen, &c., under a pressure of one or two millimetres, exhibit beautiful appearances when traversed by the high tension current produced by the secondary circuit of an induction coil.
Ampere floated a voltaic battery with a coil of wire in its circuit in order to observe the effects of the earth's magnetism on the electric circuit.
The spark may be obtained from the secondary of an induction coil, whose terminals are in connexion with the coatings of a Leyden jar.
A still greater improvement may be effected by using an electrically maintained fork, which performs the double office of controlling the resolution of the jet and of interrupting the primary current of the induction coil.
Henry appears to have been the first to adopt insulated or silkcovered wire for the magnetic coil; and also the first to employ what may be called the "spool" winding for the limbs of the magnet.
He was also the first to demonstrate experimentally the difference of action between what he called a "quantity" magnet excited by a "quantity" battery of a single pair, and an "intensity" magnet with long fine wire coil excited by an "intensity" battery of many elements, having their resistances suitably proportioned.
Early in 1831 he arranged a small office-bell to be tapped by the polarized armature of an "intensity" magnet, whose coil was in continuation of a mile of insulated copper wire, suspended about one of the rooms of his academy.
In the course of division two bodies appear in the cytoplasm, and behave as centrosomes during the karyokinesis; they gradually become threadlike and coil round each daughter nucleus.
The extension of a spiral spring is given by the formula: Extension =W4n1VÃ† r 4, in which W = weight causing extension, in lbs; n = number of coils; R = radius of spring, from centre of coil to centre of wire, in inches; r = radius of wire of which the spring is made, in inches; E = coefficient of elasticity of wire, in lbs per square inch.
5) is fixed, and the other B is movable, and a rope or chain, with one end secured to one of the blocks at C, passes round the sheaves in a continuous coil, leaving a free end D at which the effort is applied.
Hence according to the magnitude of each coil the total resistance may be made anything from I to 9, 10 to 90, or 100 to goo ohms, &c. Three or four of the " dials " thus composed are arranged side by side, the brass blocks being mounted on a slab of ebonite and the coils contained in the box underneath, and they are so joined up that the central block of one dial is connected to the outside block of the next marked O.
measurements the chief difficulty, however, is not to determine the resistance of a coil, but to determine the temperature of the coil at the time when the resistance measurement is made.
19 a caused by the fact that the coil is heated by the current used to measure its resistance, which thus alters in value.
In accurate comparisons, therefore, it is necessary that the coils to be compared should be immersed in melting ice, and that sufficient time should be allowed to elapse between the measurements for the heat generated in the coil to be removed.
This is soldered to two thick terminal rods of copper, and the coil is enclosed in a water-tight brass cylinder so that it can be placed in water, or preferably in paraffin oil, and brought to any required temperature.
In the form of standard coil recommended by the Berlin Reichsanstalt the coil is immersed in an insulating oil which is kept stirred by means of a small electric motor during the time of making the measurement.
If the plate receives a mixed charge, as, for example, from an induction coil, a "mixed" figure results, consisting of a large red central nucleus, corresponding to the negative charge, surrounded by yellow rays, corresponding to the positive charge.
The solution of the extracted oil or fat is then transferred to a steam-heated still, where the solvent is driven off and recovered by condensing the vapours in a cooling coil, to be used again.
On heating the solvent with steam through a coil or jacket, the vapours rise through and around the meal.
The refrigerator, which, Refrigerator Condenser T, Compressor consists of a coil or series of coils, is connected to the suction side of the pump, and the delivery from the pump is connected to the condenser, which is generally of somewhat similar construction to the refrigerator.
The pressure in the refrigerator being reduced by the pump and maintained at such a degree as to give the required boiling-point, which is of course always lower than the temperature outside the coils, heat passes from the substance outside, through the coil surfaces, and is taken up by the entering liquid, which is converted into vapour at the temperature T i.
Eggs protected by the parents who coil themselves round or "sit" on them.-Mantophryne, Desmognathus, Autodax, Plethodon, Cryptobranchus, Amphiuma, Ichthyophis, Hypogeophis, Siphonops.
They consist essentially of a galvanometer of which the needle or coil has such a short natural periodic time that it can follow all the variations of a current which runs through its cycle in say i;nth second.
This needle or coil must be so damped that when the current is cut off it returns to zero at once without overshooting the mark.
He elbowed her away and grabbed a large coil of mountain-climbing rope and a flashlight larger than his.
Dean continued to move, clutching the rope in a loop around his body while the unspent coil remained slung over his shoulder.
A shunt is resistive device used to generate a small signal voltage to display current on a moving coil ammeter.
Depending on which coil was energized, one or other of the phosphor bronze wipers was supposed to engage with the associated iron armature.
A keyring type attachment clips onto your clicker, and the colorful wrist coil makes sure it stays where you want it.
The Eroica is a true audiophile moving coil cartridge which features an advanced pole shoe design using a powerful rare earth Neodymium magnet.
COIL magazine - 1999 The Raw and the Cooked - The fourth ICA biennial.
Moving coil, moving magnet The most common types of phono cartridges.
coil of rope beside the main mast.
At least when you shuffle off your mortal coil, the coffin will only have two corners damaged.
Often the magnet is a superconducting solenoid coil which requires cooling to the temperature of liquid helium.
Precision cold rolled coil being slit to narrow strips. © Outokumpu Stainless Another form of cold processing is cold drawing.
Unsure about my new contraceptive coil Will ab toner affect the coil?
coil pickups on a full size body are accented by a traditionally shaped sound hole.
coil actuator technology.
coil loudspeakers use some kind of magnet system to produce the movement within the voice-coil.
Conclusion Please note that building a solid state tesla coil IS NOT EASY.
The ignition coil that is suitable for the hall sensor ignition MUST have a yellow label.
I also have a mirena coil which is also meant to stop periods.
The new Toshiba system has replaced an aging four-pipe fan coil system which affected half the building's usage during a system failure.
contraceptive coil can be fitted during the operation.
Sheringham fisherman and lifeboat coxswain John ' Sparrow ' Hardingham, wearing a typical Sheringham pattern gansey of herringbones and coil o ' rope.
cubic zirconia set at either end of the ' coil ' .
This involved changing from lever arm dampers with coil springs to telescopic dampers and torsion bars.
distributor cap, moved the coil and disconnected the fuel filter to see if that helped.
Placed inside the return air ductwork is an evaporator coil.
American Joseph Henry produced the first electromagnet when he wrapped a coil of insulated electrical wire around a metal inner.
flipper coil correctly.
glycol cooled condensers and a second cooling coil, interlaced with the main evaporator coil.
The ignition coil that is suitable for the hall sensor ignition coil that is suitable for the hall sensor ignition MUST have a yellow label.
There is a section that goes on to describe various ignition systems opting for the Trembler coil type ignition.
inductance of the coil.
A very comprehensive collection: Mutual and self inductance for all geometries of air coil, the force between coils.
The pendulum's motion can be detected using an induction coil.
At the center of the receive coil is an 18 turn spiral inductor, with an innermost diameter of approximately 46mm.
Never use the spark coil in the vicinity of flammable liquids or gases.
Magnetically shielded All moving coil loudspeakers use some kind of magnet system to produce the movement within the voice-coil.
The coercivity of relay steels and other magnetically soft materials can be measured using a vibrating coil magnetometer developed at NPL for this purpose.
The search coil is boom mounted, using the same boom as the fluxgate magnetometer in the core payload.
mortal coil, the coffin will only have two corners damaged.
The Eroica is a true audiophile moving coil cartridge which features an advanced pole shoe design using a powerful rare earth neodymium magnet.
ohmmeter check will verify an open field coil.
oscilloscope traces showing the Secondary voltage field produced by a sparking Tesla Coil.
peak voltage, and delivers more power into the Tesla Coil system.
pendulum's motion can be detected using an induction coil.
The sensors contain a permanent magnet and wire coil.
Company founder, Joseph Grado is credited as the inventor of the stereo moving coil phono cartridge.
Top of the line was the P46 Deluxe pickup assembly, perhaps the first arrangement to feature four single coil pickup assembly, perhaps the first arrangement to feature four single coil pickups.
Two single coil pickups on a full size body are accented by a traditionally shaped sound hole.
For systems without a tank stat, it is vital to insulate the pipes adjacent to the tank that feed the heating coil.
Hard disk platter sits on coil, with CD above it.
A modern studio potter produces a vertical handle by rolling out a coil of clay.
One often sees short monopoles with a coil at the foot, to provide inductive tuning for this capacitative reactance.
receiver coil can be used to detect the amplitude of this magnetic field.
This boiling liquid refrigerant absorbs heat energy from the interior space through the walls of this interior coil.
Electrical resistivity: Non contact resistivity measurements using a unique double paired coil induction method.
resistor in series with the generator field coil.
However the inertia of the coil reduces high frequency response.
It's a system with proven advantages over the more common coil spring and oil/air sh... ... .
shuffle off this mortal coil.
shuffled off this mortal coil, Must give us pause.
sloughed off this mortal coil on November 16th 1994, aged fifty-seven.
The pump also has a fuel cutoff valve, operated by a solenoid with a removable coil.
solenoid coil, if you do not find any mechanical problems.
spark plug wires and the coil wire, and haven't had the problem since.
Choose between a lightweight air shock or bomber duty coil spring.
In order to recover the signal lost by using a low magnetic field a receive coil made from high temperature superconductor will be used.
supply voltage on the coil.
There are three single - coil pick-ups installed in neck, middle and bridge positions, with a selector switch yielding five different settings.
tesla coil with a much faster timebase setting.
A traditional coil or toroidal transformer works very well for whole circuits of low voltage fittings, or for outside use.
These clamps are important as they suppress coil vibration transmitted from the engine.
transmitter coil which is worn on the side of the head.
triaxial coil system shown in the picture is used.
The conventional domed tweeter is convex, with a voice coil of the same diameter.
The ignition coil receives current whilst the metal vane is passing through the magnetic field of the hall sensor.
voltage induced in the coil is proportional to the change in flux through it (Faraday's Law?
waggon carried the rope to the cave in a large coil, rolling it along down the passage like a wagon wheel.
This is when the primary windings of the coil begin to flow current and " charge " the primary side of the coil.
The coil windings forma transformer having a 1:1 ratio.
The suspension is fully independent with coil springs, double wishbones and 6 hydraulic dampers.
wishbone with coil over shocks.
zirconia set at either end of the ' coil ' .
thick) continues from the top of the coil, and after travelling round the various apartments returns to, and is connected with, the lowest part of the boiler coil.
Upon the application of heat to the fire-box coil the water naturally expands and forces its way up into the expansion chamber; but there it encounters the pressure of the confined air, and ebullition is consequently FiG.
To each radiator should be fitted an air tap, which when opened will permit the escape of any air that has accumulated in the coil; otherwise free circulation is impossible, and the full benefit of the heat is not obtained.
Water may also be heated by placing a coil of steam or high-pressure hot-water pipes in a water tank (fig.
The deflection observed on the galvanometer when the lines are leaky is d, while D is the deflection obtained through one coil of the galvanometer with all the other resistances in circuit; and assuming that no leakage exists on the lines, this deflection is calculated from the " constant " of the instrument, i.e., from the known deflection obtained with a definite current.
a key K to one end of the coil of the relay magnet R, II the other end of which is put to earth.
The spark coil has a resistance about ten times as great as that of the electromagnet it shunts, and the wire of which it is composed is double wound so as to have no retarding effect on the induced current, which circulates through the spark coil instead of jumping in the form of a spark across the contact points.
The compensation was to be obtained by working a slide resistance included in the circuit of the compensating coil, either by the sending key or by clockwork released by the key, so as to vary the resistance in that 0 0 circuit according to any law which might be required to prevent the receiving instrument being affected by the outgoing current.
This surface is divided into two parallel halves by a short insulating space on which the arm normally rests, so that two separate conducting surfaces are provided, with either one of which the arm will make contact in its excursions in one direction or the other from the central position, the direction and duration of contact being governed by the motion of the suspended coil.
The use of the iron core renders it possible to produce a high inductive effect with a low resistance coil, and thus obtain the necessary slow time constant to which is due the success of this type of magnetic shunt on cable signals.
The explanation of the action of the shunt is that all slowly varying currents affect the coil of the receiving instrument and its shunt in inverse proportion to their respective resistances; whereas with the comparatively rapid variations of current used in signalling the coil is forced at the beginning of each element of A v
The coil, however, is arranged so that the bridge.
By this arrangement of the coil winding, similar sections can be thrown in or out of circuit with both arms, and also so combined that any amount of inductance suitable to every class of cable may be obtained.
If a primary circuit, consisting of a large coil of wire P (fig.
The electromotive force of the coil is, however, great enough to create in these air gaps displacement currents which are of magnitude sufficient to be equivalent to the conduction current required to actuate a telephone.
In the primary circuit of the induction coil I he placed an ordinary signalling key K, and when this was pressed for a longer or shorter time a torrent of electric sparks passed between the balls, alternately charging and discharging the elevated con-.
There are three ways in which the antenna may be charged (i) It may be separated from the earth by a pair of spark balls which are connected respectively to the terminals of an induction coil or transformer, or other high tension generator.
Over the coil of one turn is wound a secondary circuit of 5 or to turns, of which one end is connected to the earth through a variable inductance and the other end to an antenna or radiating wire A (see fig.
One end of the inductance coil is connected to the earth, and some other point on the closed condenser circuit to an antenna of appropriate length.
In the early experiments Marconi connected the sensitive tube in between the receiving antenna and the earth plate, but, as already mentioned, in subsequent forms of apparatus he introduced the primary coil of a peculiar form of oscillation transformer into the antenna circuit and connected the ends of the sensitive tube to the terminals of the secondary circuit of this " jigger " (fig.
Rutherford examined it very carefully, and produced a magnetic detector for electric waves depending upon the power of electric oscillations in a coil to demagnetize a saturated bundle of steel wires placed in it (see Phil.
Up to that time an induction coil known as a ro-inch coil had sufficed for spark production, but it was evident that much more power would be required to send electric waves across the Atlantic. Transformers were therefore employed taking alternating electric current from an alternator driven by an oil or steam engine, and these high tension transformers were used to charge condensers and set up powerful oscillations in a multiple antenna.
the end of the core of a short electromagnet, the coil of which was in circuit with the line, but which had no permanent current flowing through it, answered the purpose quite as well.'
The current circuit went through S, W, C, K, A, and the primary circuit of the induction coil I to the battery B, and thence to S again.
The transmitter is placed in multiple with the primary winding of an induction coil whose secondary operates in the loop circuit, and consequently when the transmitter is spoken into, a variable E.M.F.
And now we get the Supreme Lord in his last aspect; nay, his one true and real aspect, in which the sacrificer, on shuffling off this mortal coil, will himself come to share - that of pure intellectuality, pure spirituality - he is Mind: such is the ultimate source of being, the one Self, the Purusha, the Brahman.
Next, the shell, the coil of which was at first exogastric, being also included in this rotation through 180Ã‚°, exhibits an endogastric coiling (fig.
In one well-known form, called a Siemens Electrodynamometer, there is a fixed coil (fig.
With suitable arrangements of iron and coil and a sufficiently strong current, the intensity of the temporary magnetization may be very high, and electromagnets capable of lifting weights of several tons are in daily use in engineering works (see Electromagnetism).
Just as the lines of flow of an electric current all pass in closed curves through the battery or other generator, so do all the lines of induction pass in closed curves through the magnet or magnetizing coil.
Arts, 1890, 38, 885), which consists of a rectangular block of iron shaped like Hopkinson's yoke, and slotted out in the same way to receive a magnetizing coil (fig.
A third platinum coil, wound non-inductively between the primary and the secondary, served to carry the current by which the ring was heated; a current of 4.6 amperes, with 16 volts across the terminals, was found sufficient to maintain the ring at a temperature of 11 50Ã‚° C. In the ring itself was embedded a platinum-thermometer wire, from the resistance of which the temperature was determined.
In applying this method to test the insulation of indiarubber - covered or of insulated copper wire, before employing it for electrical purposes, I I I I_ it is usual to place B the coil of wire W (fig.
In those meters which are compounded - that is, have a shunt coil wound on the field magnets to compensate for the friction of the train - it is important to notice whether the meter will operate or continue operating when there is no current in the series coil, since a meter which "runs on the shunt" runs up a debt against the consumer for which it gives no corresponding advantage.
If an electro-dynamometer, made as above described, has its fixed circuit connected in series with the power-absorbing circuit and its movable coil (wound with fine wire) connected across the terminals of the power-absorbing circuit, then a current will flow through the fixed coil which is the same or nearly the same as that through the power-absorbing circuit, and a current will flow through the high resistance coil of the wattmeter proportional to the potential difference at the terminals of the power-absorbing circuit.
The movable coil of the wattmeter is normally suspended so that its axis is at right angles to that of the fixed coil and is constrained by the torsion of a spiral spring.
This correcting factor has the follow - ing value: If Ts stands for the time-constant of the movable circuit of the wattmeter, commonly called the potential coil, the time constant being defined as the ratio of the inductance to the resistance of that circuit, and if T R is the time-constant similarly defined of the power-absorbing circuit, and if F is the correcting factor, and p = 2r times the frequency n, then,' + p2Ts2 1 For the proof of this formula see J.
Again the shunt circuit must have practically zero inductance and the series or current coil must be wound or constructed with stranded copper wire, each strand being silk Covered, to prevent the production of eddy currents in the mass of the conductor.
One of the most useful forms of electromagnetic voltmeter is that generally known as a movable coil voltmeter (fig.
For the measurement of voltages in continuous current generating stations, movable coil voltmeters are much employed, generally constructed then in the "edgewise" pattern (fig.
The extension of a spiral spring is given by the formula: Extension =W4n1VÃƒâ€ r 4, in which W = weight causing extension, in lbs; n = number of coils; R = radius of spring, from centre of coil to centre of wire, in inches; r = radius of wire of which the spring is made, in inches; E = coefficient of elasticity of wire, in lbs per square inch.
The standard resistance coil employed as a means of comparison by which to regulate and check other coils consists of a wire, generally of manganin or platinum silver, insulated with silk and wound on a brass cylinder (fig.
The generator being heated by means of a steam coil, ammonia vapour is driven off at such a pressure as to cause its condensation in the FIG.
A receiver coil can be used to detect the amplitude of this magnetic field.
Electrical Resistivity: Non contact resistivity measurements using a unique double paired coil induction method.
The carbon pile regulator is basically a resistor in series with the generator field coil.
It 's a system with proven advantages over the more common coil spring and oil/air sh.......
Coaxial coil spring shock absorber units were normally fitted all round.
Wolseley fans quietly mourned - the introduction of the Princess saw their marque finally shuffle off this mortal coil.
When we have shuffled off this mortal coil, Must give us pause.
Dino Valenti sloughed off this mortal coil on November 16th 1994, aged fifty-seven.
Check the relay coil in the same way as a solenoid coil, if you do not find any mechanical problems.
Replaced all of the spark plug wires and the coil wire, and have n't had the problem since.
The cover over the tank did not close properly when the coil was in place, so fluid could splatter everywhere.
Better to use a low output Tesla coil, which generates high voltage splattered all over the RF spectrum.
Edgar 's brave challenge ended when the coil gave way, causing him to splutter back to the pits.
This voltage has opposite polarity to the supply voltage on the coil.
These are best observed by looking at the voltage field around an operating tesla coil with a much faster timebase setting.
These parts are connected to a transmitter coil which is worn on the side of the head.
For the method cancelation of ambient magnetic fields is necessary and the triaxial coil system shown in the picture is used.
They also give protein molecules the odd ability to coil and uncoil like tiny, cellular snakes.
The voltage induced in the coil is proportional to the change in flux through it (Faraday 's Law?
They carried the rope to the cave in a large coil, rolling it along down the passage like a wagon wheel.
The brakes are ventilated disks with 4 pot calipers and the suspension is double wishbone with coil over shocks.
Do you prefer coil or foam construction?
Most people, however, buy coil mattresses.
There are several different kinds of coil constructions.
Most zippers are nylon coil and "self-healing", that is, a few zips back and forth, and any bad zipper teeth connections usually straighten out.
This is then condensed against a frozen coil inside the dehumidifier.
A good type of mattress will have a high coil count and thicker padding.
Water circulates through a large coil heated by gas or electricity.
The rotor spins the shaft which in turn spins the magnets and voltage is generated in the coil of wire.
The coil, also known as a reciprocating machine, houses a tube and needle bar.
As the coil glides over the skin's surface, the needle penetrates the dermis and distributes the color.
They can be woven into the cable or clamped on using a bolt system or by using coil springs.
Coil orthopedic dog beds with pillow tops are the top of the line models, providing the ultimate support for dogs with various joint problems.
The standard has a single Blues90, the Pro has a Blues90 and a single coil, and the Pro Twin-Six is a double neck version of the Pro so you can use different tunings on each neck.
It has a single humbucker and two single coil pickups that create a variety of sounds.
This model has 2 Epiphone open coil humbuckers and a mahogany 22-fret neck.
This guitar has a contoured body, a vintage-style vibrato, two single coil and one humbucker pickup, and a rosewood fingerboard.
A deep cutaway alder body, two piece flame maple neck, birdseye maple fingerboard, Gotoh machine heads, and a hand wound Alnico single coil with a hand wound Alnico V humbucker come together to make a great instrument.
The refrigerant is sent through an expansion device that turns it back into an ice-cold liquid where it returns to the evaporator coil to start the whole process over again.
An electrical current passes through a high-resistance coil to power these heaters.
The CM935 Series feature rectangular clipons, all with an adjustable spring coil.
Shoot them in the following order, and then kill Gorea to face Gorea 2: Yellow (Volt Driver), Green (Warhammer), Orange (Magmaul), Blue (Shock Coil), Purple (Judicator), and finally Red (Imperialist).
Then a tiny coil is fed through the tube into the aneurysm "balloon" to fill the space and seal off the bleeding.
For head imaging, the coil may be shaped like a head or neck rest.
Device closure of PDA is a medical procedure in which a device such as a coil, very small rings of wire, or an occluder, a tiny wire mesh patch, is placed over the PDA causing the blood to clot and thus closing the open ductus.
To style, simply gather the hair at the nape of the neck into a low ponytail, twist and coil, tuck the ends in and secure with bobby pins.
Bun: With a bun, you can either wear it in the traditional style, or you can braid your hair and then coil it up.
Coil - a device placed in the cervix that contains hormones that are released into the blood stream.
The coil can be left in for up to five years.