What I have up there is just a power source and magnetic field.
In the receiver there is a strong electromagnet, excited by a local current, which has in its circuit two annular air gaps, across which the magnetic field is practically uniform and constant.
Willoughby Smith found that it was not necessary even to connect the telephone to a secondary circuit, but that it would be affected and give out sounds merely by being held in the variable magnetic field of a primary circuit.
Hartog has endeavoured to show that it can only he formed by a dual force, analagous to that of magnetism, the spindle-fibi es being comparable to the lines of force in a magnetic field and possibly due to electrical differences in the cell.
construction of this instrument is as follows: - Within the instrument is a horseshoe magnet having soft-iron pole pieces so arranged as to produce a uniform magnetic field.
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 regions of greatest attraction have received the name of poles, and the line joining them is called the axis of the magnet; the space around a magnet in which magnetic effects are exhibited is called the field of magnetic force, or the magnetic field.
In a refined form this method is often employed for measuring the intensity of a magnetic field at a given place, just as the intensity of gravity at different parts of the earth is deduced from observations of the rate at which a pendulum of known length vibrates.
Any space at every point of which there is a finite magnetic force is called a field of magnetic force, or a magnetic field.
The strength or intensity of a magnetic field at any point is measured by the force in dynes which a unit pole will experience when placed at that point, the direction of the field being the direction in which a positive pole is urged.
A line of force is a line drawn through a magnetic field in the direction of the force at each point through which it passes.
A uniform magnetic field is one in which H has everywhere the same value and the same direction, the lines of force being, therefore, straight and parallel.
A magnetic field is generally due either to a conductor carrying an electric current or to the poles of a magnet.
The magnetic field due to a long straight wire in which a current of electricity is flowing is at every point at right angles to the plane passing through it and through the wire; its strength at any point distant r centimetres from the wire is H = 21/r, (2) i being the current in C.G.S.
The magnetic potential at any point in a magnetic field is the work which would be done against the magnetic fdrees in bringing a unit pole to that point from the boundary of the field.
In a uniform magnetic field of unit intensity formed in empty space the induction or magnetic flux across an area of I square centimetre normal to the direction of the field is arbitrarily taken as the unit of induction.
These free poles produce a magnetic field which is superposed upon that arising from other sources.
It is found that when a piece of ferromagnetic metal, such as, iron, is subjected to a magnetic field of changing intensity, the changes which take place in the induced magnetization of the iron exhibit a tendency to lag behind those which occur in the intensity of the field - a phenomenon to which J.
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.
Forces acting on a Small Body in the Magnetic Field.-If a small magnet of length ds and pole-strength m is brought into a magnetic field such that the values of the magnetic potential at the negative and positive poles respectively are V 1 and the work done upon the magnet, and therefore its potential energy, will be W =m(V2-Vi) =mdV, which may be written W =m d s- = M d v= - MHo = - vIHo, ds ds where M is the moment of the magnet, v the volume, I the magnetization, and Ho the magnetic force along ds.
- An electric current i flowing uniformly through a cylindrical wire whose radius is a produces inside the wire a magnetic field of which the lines of force are concentric circles around the axis of the wire.
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.
Therefore and m = v I - 'm of d22 (47) constant cell B21 its object is to produce inside the tube a magnetic field equal and opposite to that due to the earth's magnetism.
The fact, which will be referred to later, that the electrical resistance of bismuth is very greatly affected by a magnetic field has been applied in the construction of apparatus for measuring field intensity.
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.
Specimens of curves showing the relation of induction to magnetic field at various temperatures, and of permeability to temperature with fields of different intensities, are given in figs.
But the application of a magnetic field at right angles to the plane of the metal causes the equipotential lines to rotate through a small angle, and the points at] which the galvanometer is connected being no longer at the same potential, a current is indicated by the galvanometer.'
Electro-Thermal Relations.-The Hall electromotive force is only one of several so-called " galvano-magnetic effects " which are observed when a magnetic field acts normally upon a thin plate of metal traversed by an electric current.
The curves given by Houllevigue for the relation of thermo-electric force to magnetic field are of the same general form as those showing the relation of change of length to field.
As to what effect, if any, is produced upon the thermo-electric quality of bismuth by a magnetic field there is still some doubt.
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.
The creation of an external magnetic field H will, in accordance with Lenz's law, induce in the molecule an electric current so directed that the magnetization of the equivalent magnet is opposed to the direction of the field.
As a consequence of the structure of the molecule, which is an aggregation of atoms, the planes of the orbits around the latter may be oriented in various positions, and the direction of revolution may be right-handed or left-handed with respect to the direction of any applied magnetic field.
C. Oersted 6 that a magnet placed near a wire carrying an electric current tended to set itself at right angles to the wire, a phenomenon which indicated that the current was surrounded by a magnetic field.
A single vortex will remain at rest, and cause a velocity at any point inversely as the distance from the axis and perpendicular to its direction; analogous to the magnetic field of a straight electric current.
The latter is slit radially, and the magnetic field is so arranged that it perforates each half of the disk in opposite directions.
Induced or eddy currents are thus created in the copper disk, and the reaction of these against the magnetic field offers a resistance to the rotation of the disk.
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.
that it is doubled instead of being undone when the light retraces its path, requires the operation of some directed agency of a rotational kind, which must be related to the magnetic field.
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.
This magnetic field may be made to cause a displacement 0 FIG.
The study of these vortices has led to the discovery of a magnetic field in sun-spots, apparently caused by electric convection in the vortices.
The rapid variation in the intensity of the magnetic field causes a brilliant electrodeless discharge which is seen in the form of a ring passing near the inner walls of the bulb when the pressure is properly adjusted.
MAGNETOMETER, a name, in its most general sense, for any instrument used to measure the strength of any magnetic field; it is, however, often used in the restricted sense of an instrument for measuring a particular magnetic field, namely, that due to the earth's magnetism, and in this article the instruments used for measuring the value of the earth's magnetic field will alone be considered.
It is clear, moreover, that Oersted clearly recognized the existence of what is now called the magnetic field round the conductor.
The 22nd series (1848) is occupied with the discussion of magnetocrystallic force and the abnormal behaviour of various crystals in a magnetic field.
In the interval between his election and the assumption of his duties at Baltimore, he studied physics under Helmholtz at Berlin, and carried out a well-known research on the effect of an electrically charged body in motion, showing it to give rise to a magnetic field.
But a far more important instance of induced activity is afforded by Michael Faraday's discovery of the rotary polarization connected with a magnetic field.
This subject is treated in the article Magneto-Optics, to which the reader is also referred for John Kerr's discovery of the effect on polarization produced by reflection from a magnetic pole, and for the action of a magnetic field on the radiation of a source - the "Zeeman effect."
The magnets are either sintered or directionally cast, and then annealed in a magnetic field.
antiparticle pairs, by studying their trajectories in a magnetic field.
caesiumargest shift in the frequency of any cesium standard is due to the magnetic field in the interaction region.
Therefore, thicker clumps have much higher damping rates of waves  which support clumps against collapse along the large-scale magnetic field.
A unified model of the response of ionospheric convection to changes in the interplanetary magnetic field.
The magnetic field of the Earth is generated in its molten iron core.
The Sun's Magnetic Field The orbital period of 3750 years finds a remarkable corollary in research conducted by the author Maurice Cotterell.
The hot corona is heated by the magnetic field.
coronal plasma resembles very much the typical magnetic field topology expected for the Sun.
cosmic ray flux, which would otherwise be isotropic, is shaped by the Earth's magnetic field.
currents induced by a changing magnetic field.
The magnetic field attracts the thin diaphragm which bends toward the magnet.
Moreover any alternating magnetic field will induce an electric field in the tissues exposed to it.
When placed between the poles of a strong electromagnet, diamagnetic materials are attracted toward regions where the magnetic field is weak.
But the incoming cosmic ray flux, which would otherwise be isotropic, is shaped by the Earth's magnetic field.
One involves experimental and numerical research into the behavior of liquid gallium under the combined action of a temperature gradient and a magnetic field.
gauss line is the only location where the static magnetic field strength is specified around an MR scanner.
The black lines show the magnetic field lines in the sample, measured using electron holography.
The fine white lines are the magnetic field lines in the cell, which were measured using off-axis electron holography.
Description: The curved lines (generated by a computer program written by me) represent the magnetic field from an induction loop antenna.
The iron-rich minerals in the magma record the direction of the Earth's magnetic field at the time when the rising magma solidified.
To produce a stable uniform high magnetic field usually requires a superconducting magnet.
Magnetic susceptibility The magnetic susceptibility of a material is its ability to become magnetized by an external magnetic susceptibility The magnetic susceptibility of a material is its ability to become magnetized by an external magnetic field.
This experiment's goal is the observation of currents induced by a changing magnetic field.
No one, for instance, could experience a magnetic field without a bit of iron to test it with.
Magnetic susceptibility relates to the induced magnetism of a material when in the presence of a magnetic field.
British Antarctic Survey have developed a low power magnetometer for measuring the three components of the earth's magnetic field using a TDS2020 F.
tunnel junction magnetoresistance (JMR) is yet another approach to transforming a tiny magnetic field into a change in resistance.
Changes in magnetic field geometry while the spacecraft is traversing the transition region between the outer and middle magnetosphere are also considered.
periodic modulation in the magnetic field can be treated in the same way.
mole of non-interacting sodium atoms is placed in a magnetic field B.
The resultant magnetic field causes temporary optical illusions and distortions.
Therefore the nominal dipole magnetic field direction is approximately perpendicular to the spin axis.
These two models can be distinguished by considering the ratio of the magnetic field perturbation to the electric field.
But he did find that the magnetic polarity was the opposite of the Earth's present magnetic field.
In this diagram, young, high magnetic field radio pulsars are located in the upper part.
radio frequency used, which in turn depends on the magnetic field strength.
receiver coil can be used to detect the amplitude of this magnetic field.
resonance frequency reaches 13 cycles we will be at a zero point magnetic field.
The process, called inverse electron spin resonance, uses the magnetic field to deflect electrons and to modify their magnetic direction.
The effects of oblique propagation and a magnetic field shear are taken into account.
A long thin strip of conductive foil moves within a magnetic field to generate a current hence voltage.
In order to recover the signal lost by using a low magnetic field a receive coil made from high temperature superconductor will be used.
superconductor in the presence of a magnetic field.
The fluxgate sensor mounted on the telescope of a non-magnetic theodolite is used to detect when it is perpendicular to the magnetic field vector.
thin strip of conductive foil moves within a magnetic field to generate a current hence voltage.
tokamak plasma has a lower magnetic field than the inside.
This material becomes ionized in the magnetic field and forms a doughnut-shaped cloud of intense radiation referred to as a plasma torus.
The ignition coil receives current whilst the metal vane is passing through the magnetic field of the hall sensor.
Away from Ground Zero the magnetic field lines are not vertical.
wavelet based analysis method using Ulysses polar magnetic field data, which is particularly well suited to this work.
36), has in circuit a battery B and an in terrupter I, and at some distance and parallel to this primary circuit is placed a secondary circuit S, having a telephone T included in it, the interruptions or reversals of the current in the primary circuit will give rise to a varying magnetic field round that circuit which will induce secondary currents in the other circuit and affect the telephone receiver.
Tesla effected this purpose by placing the spark balls transversely in a powerful magnetic field.
An electric current in a conductor is recognized by its ability (a) to create heat in a wire through which it passes, (b) to produce a magnetic field round the conductor or wire.
The heat makes itself evident by raising the temperature and therefore elongating the wire, whilst the magnetic field creates mechanical forces which act on pieces of iron or other conductors conveying electric currents when placed in proximity to the conductor in question.
On the other hand, hot-wire instruments are very " dead-beat," that is to say, the needle does not move much for the small fluctuations in the current, and this quality is generally increased by affixing to the index needle a small copper plate which is made to move in a strong magnetic field (see fig.
Instruments of this type with a permanent magnetic field are only available for the measurement of continuous currents, but soft-iron instruments of II??II?NIIIiIC?p u??i?,,.
Soc., 1886, 40, 486), who in 1886 published an account of some experiments in which the relation of magnetization to magnetic field was deduced from observations of the force in grammes weight which just sufficed to tear asunder the two halves of a divided ring electro-magnet when known currents were passing through the coils.
The actual chemical shift depends on the radio frequency used, which in turn depends on the magnetic field strength.
My husband published, beside, a study of the action of a magnetic field on radium rays.
A receiver coil can be used to detect the amplitude of this magnetic field.
When the Earth stops its rotation and the resonance frequency reaches 13 cycles we will be at a zero point magnetic field.
Where the material is used to generate a magnetic field or to create a force then the saturation magnetization may also be significant.
Chill a superconductor in the presence of a magnetic field.
Trapped particles The outside (larger major radius portion) of a tokamak plasma has a lower magnetic field than the inside.
We present a new, wavelet based analysis method using Ulysses polar magnetic field data, which is particularly well suited to this work.
Using silicon or another form of semi-conductor, solar panels convert light into energy by creating a flow of electrons and a magnetic field.
Nuclear magnetic resonance (NMR) lipoprofile exposes a blood sample to a magnetic field to determine the size of the cholesterol particles.
The scanner, which is usually shaped like a large rectangle with a hole in the center, contains the systems that generate the magnetic field.
However, the magnetic field generated during an MRI examination is so strong that metal objects or objects with metal in them, such as jewelry, eyeglasses, oxygen canisters, and even wheelchairs, will be pulled toward the machine.
Just as the magnetic field varies depending on where you are positioned on the earth, some theorists believe that "Time'", as a force of nature, can also get warped based on your location.
The word usage examples above have been gathered from various sources to reflect current and historial usage. They do not represent the opinions of YourDictionary.com.