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Topic: Magnetic moment


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In the News (Fri 16 Nov 18)

  
  Magnetic moment - Wikipedia, the free encyclopedia
The moment is negative, indicating it is diamagnetic, and equal to the energy of rotation divided by the magnetic field.
Magnetism can be created by electric current in loops and coils so any current circulating in a planar loop produces a magnetic moment whose magnitude is equal to the product of the current and the area of the loop.
The magnetic moment of an object is a vector relating the aligning torque in a magnetic field experienced by the object to the field vector itself.
en.wikipedia.org /wiki/Magnetic_moment   (681 words)

  
 Magnetism - Wikipedia, the free encyclopedia
Normally, magnetic fields are seen as dipoles, having a "South pole" and a "North pole"; terms dating back to the use of magnets as compasses, interacting with the Earth's magnetic field to indicate North and South on the globe.
Alnico magnets are made by casting or sintering a combination of aluminium, nickel and cobalt with iron and small amounts of other elements added to enhance the properties of the magnet.
Flexible magnets are similar to injection molded magnets, using a flexible resin or binder such as vinyl, and produced in flat strips or sheets.
en.wikipedia.org /wiki/Magnetism   (1932 words)

  
 Magnetic moment   (Site not responding. Last check: 2007-10-08)
From the expression for the torque on a current loop, the characteristics of the current loop are summarized in its magnetic moment
The direction of the magnetic moment is perpendicular to the current loop in the right-hand-rule direction, the direction of the normal to the loop in the illustration.
The position where the magnetic moment is opposite to the magnetic field is said to have a higher magnetic potential energy.
hyperphysics.phy-astr.gsu.edu /hbase/magnetic/magmom.html   (300 words)

  
 Nuclear magnetic resonance - Wikipedia, the free encyclopedia
NMR studies a magnetic nucleus, like that of a hydrogen atom, protium being the most receptive isotope at natural abundance, by aligning it with a very powerful external magnetic field and perturbing this alignment using an electromagnetic field.
The sensitivity of nuclear magnetic resonance signals is also dependent, as noted above, on the presence of a magnetically-susceptible nuclide, and therefore either on the natural abundance of such nuclides, or on the ability of the experimentalist to artificially enrich the molecules under study with such nuclides.
A relatively recent example of nuclear magnetic resonance being used in the determination of a structure is that of buckminsterfullerene.
en.wikipedia.org /wiki/Nuclear_magnetic_resonance   (3126 words)

  
 Magnetic Moment   (Site not responding. Last check: 2007-10-08)
Magnetic moment results from the interaction between two charged bodies or between two centers of charge in a single body.
It might be that the magnetic moment and angular momentum of fundamental particles are affected by the expansion of the universe and the expansion acts on charge and mass to create charge asymmetry.
In other words, the asymmetry indicated by the magnetic moment of fundamental particles could be caused by an asymmetric expansion of the universe.
home.earthlink.net /~tdp/magmom.html   (244 words)

  
 A Measure of Magnetic Moment and Earth’s Magnetic Field
The frequency of oscillation of a bar magnet placed in the center of a current coil with a magnetic field parallel to earth’s magnetic field can be measured as a function of the current in the loop.
As such the magnetic dipole moment of the bar magnet and the magnetic field of the earth can be determined from the slope and y-intercept of the line.
Once the apparatus was properly aligned, ten periods of the bar magnet at a displacement angle of 15° ± 5° was measured from 0 to 0.800 A of current in the loop.
www4.hmc.edu:8001 /physics/28spring2005/sample2.html   (1375 words)

  
 What is a magnetic field?
A magnet produces a vector field, the magnetic field, at all points in the space around it.
A magnetic field can also be created by the spin magnetic dipole moment, and by the orbital magnetic dipole moment of an electron within an atom.
By convention, we state that the magnetic field has a direction associated with it, such that the field exits the North end of a magnet, flows through the air or other materials nearby, and re-enters the South end of the magnet.
my.execpc.com /~rhoadley/magfield.htm   (718 words)

  
 Magnetic properties of materials
At an atomic level ferromagnetism is explained by a tendency for neighbouring atomic magnetic moments to become locked in parallel with their neighbours.
However, the magnetic moments in one direction are weaker than the moments in the opposite direction leading to an overall magnetic moment.
In a bar magnet you may not think that there need be any current but the magnetic field here is also due to moving charge: the electrons circling around the nuclei of the iron atoms or simply spinning about their own axis.
www.ee.surrey.ac.uk /Workshop/advice/coils/mu   (3940 words)

  
 [No title]
Magnetization effects are due to the propensity of the atomic constituents of matter to behave as magnetic dipoles.
An estimate of the moment that would result if each atom or molecule of a material contributed only one Bohr magneton shows that the orbital and spin contributions from all the electrons comprising a typical solid had better tend to cancel or the resulting field effects would be prodigious indeed.
Similarly, the force experienced as a piece of iron is brought into a magnetic field is common evidence of the induced magnetization described by the constitutive laws of Sec.
web.mit.edu /6.013_book/www/chapter9/9.0.html   (899 words)

  
 Magnetic Moment
The g-factor is an essential value related to the magnetic moment of the subatomic particles and corrects for the precession of the angular momentum.
From the expressions of magnetic moment in the Aether Physics Model, it appears that magnetic moment is physically caused by the interaction of the electrostatic and electromagnetic charges within each particle.
Since the electron and proton magnetic moments can be calculated exactly by applying quantum measurements, and that the APM neutron magnetic moment is calculated using quantum measurements, it is likely that the error lies with the NIST value of neutron magnetic moment.
www.16pi2.com /magnetic_moment.htm   (915 words)

  
 MAGNETIC MATERIALS
Since this magnetic moment is associated with the orbital motion of the electron around the nucleus it is called the orbital magnetic moment.
The total magnetic moment of an atom is equal to the vector sum of the orbital magnetic moments and the intrinsic magnetic moments of all its electrons.
This means an increase in the orbital magnetic moment if the orbital magnetic field is directed in a direction opposite to the external field, and a decrease in the orbital magnetic moment if the orbital magnetic field is directed in the same direction as the external field.
teacher.nsrl.rochester.edu /phy122/Lecture_Notes/Chapter33/chapter33.html   (1812 words)

  
 No Title
Magnetic materials are composed of magnetic moments that reside on the atoms of the magnetic materials.
Calculation of the magnetic properties thus depends on the details of the atomic bonding in materials which is a quantum physics problem.
The magnetic properties of atoms comes from a combination of the orbital motion of the electrons about the nucleus and the intrinsic spin of electrons, protons and neutrons.
www.pa.msu.edu /~duxbury/courses/phy294H/lectures/lecture27/lecture27.html   (558 words)

  
 Magnetic Dipole Moment
The magnetic dipole moment of a substance (how well it acts as a magnet) can be determined by suspending a sample of the substance on a torsion fiber and measuring the period of the oscillations of the sample in an applied magnetic field.
The equation of motion of the magnetic torsional oscillator is gven by
Use the magnetic dipole moment of the magnet and the y-intercept of the plot to calculate the horizontal component of the Earth's magnetic field.
www.physics.smu.edu /~scalise/emmanual/dipole/lab.html   (1131 words)

  
 Materials by Design: Magnetic Materials   (Site not responding. Last check: 2007-10-08)
Magnetic materials get their properties from the electrons of the atoms in the materials.
Depending on the way these magnetic moments interact with each other, a material can exhibit one of the four different types of magnetism.
Magnetic materials are used in electrical power applications such as transformers and motors, in video monitor picture tubes to move electron beams, and in computer disks or video or audio tapes to record information.
www.mse.cornell.edu /courses/engri111/magnet.htm   (220 words)

  
 IBM Think Research
Because magnetic memory cells maintain their state even when power is removed, MRAM possesses a distinct advantage over electrical cells.
Passing a small electric current directly through the memory cell accomplishes this: when the moments are parallel, the resistance of the memory cell is smaller than when the moments are not parallel.
IBM holds patents on both the crosspoint architecture of the magnetic junctions and the knowledge of the materials and physics involved.
www.research.ibm.com /thinkresearch/pages/2001/20010202_mram.shtml   (944 words)

  
 Physics Today April 2001
An early triumph of quantum electrodynamics was Julian Schwinger's 1948 calculation of the first-order radiative correction to the naïve Dirac magnetic moment of the electron.
Assuming, for the moment, that it's not a statistical fluke or an experimental blunder, the first thing a discrepancy of this size suggests is "supersymmetric" effects beyond the standard model.
At the heart of their undertaking was a proposal to build a 14-meter-diameter muon storage ring with an iron-core superconducting magnet producing a 1.5-tesla bending field of unprecedented stability and homogeneity throughout the ring's 9-cm beam aperture.
physicstoday.org /pt/vol-54/iss-4/p18.html   (1497 words)

  
 Physics Tutoring: Magnetism in Matter   (Site not responding. Last check: 2007-10-08)
Destruction of macroscopic net magnetism does not mean that individual atoms do not have a magnetic moment, but that the orientation of atomic magnetic moments is random.
A: The end of a magnetic needle of a compass that points toward the magnetic North pole of the earth is the South pole of the needle.
Ferromagnetic materials: materials, in the absence of an external magnetic field, in which some of the electrons have their magnetic dipole moments aligned by means of a quantum physical interaction called exchange coupling, producing regions (domains) within the material with strong magnetic dipole moments.
www.slcc.edu /schools/hum_sci/physics/tutor/2220/magnetism_in_matter   (667 words)

  
 Principles of Magnetic Resonance Imaging
The process of detecting metabolites by NMR is known as magnetic resonance spectroscopy (MRS) and the first MR spectrum of a human tumour was obtained by Griffiths et al.
The strength of the magnetic moment is a property of the type of nucleus.
The magnetic moments or spins are constrained to adopt one of two orientations with respect to B0, denoted parallel and anti-parallel.
www.easymeasure.co.uk /principlesmri.aspx   (4001 words)

  
 "Nanotorus" nets giant magnetic moment (May 2002) - News - PhysicsWeb
In their calculations, the researchers assume that the nanotori are in a magnetic field of 0.1 tesla, which causes the spins of the electrons to line up, producing a magnetic moment.
When the researchers calculated the magnetic moments of the nanotori, they found that some of the nanotori made from either ‘armchair’ or ‘zigzag’ metallic nanotubes had magnetic moments thousands of times larger than other tori with similar structures.
The team realised that the radius of the torus – and therefore the area it enclosed – affected its magnetic moment.
physicsweb.org /article/news/6/5/13/1   (452 words)

  
 Off axis field due to a magnetic dipole moment
B is the magnetic field, in teslas, at any point in space that isn't at the origin.
A magnetic dipole moment is a simple mathematical representation of a coil, electromagnet or permanent magnet ("refrigerator magnet") that can be used to predict the magnetic field at a distance from its source.
is the "intrinsic induction" of the magnet, in teslas,
www.netdenizen.com /emagnet/offaxis/mmoffaxis.htm   (533 words)

  
 lecture 18
Paramagnetic materials: Materials which can be magnetized by a magnetic field and the magnetization is in the same direction of the magnetic field.
Diamagnetic materials: Materials which can be magnetized by a magnetic field but the magnetization is in the opposite direction of the magnetic field.
Magnetization (M): Just because the atoms in a materials possess magnetic dipole moment does not mean that the material is a magnet.
www2.hawaii.edu /~plam/ph272_old/L18/lecture18.html   (954 words)

  
 NMR Spectroscopy
The magnetic moment of the lower energy +1/2 state is alligned with the external field, but that of the higher energy -1/2 spin state is opposed to the external field.
For spin 1/2 nuclei the energy difference between the two spin states at a given magnetic field strength will be proportional to their magnetic moments.
Since the deuterium isotope of hydrogen has a different magnetic moment and spin, it is invisible in a spectrometer tuned to protons.
www.cem.msu.edu /~reusch/VirtualText/Spectrpy/nmr/nmr1.htm   (6032 words)

  
 Orbital Magnetic Moment   (Site not responding. Last check: 2007-10-08)
The magnetic moment associated with an electron orbit is given by
A unit of magnetic moment called the "Bohr magneton" is introduced here.
The z-component of the magnetic moment is given by
hyperphysics.phy-astr.gsu.edu /hbase/quantum/orbmag.html   (83 words)

  
 Nuclear Magnetic Resonance (NMR)
The practical uses for this phenomenon are for determining the value of nuclear magnetic moments by comparison with the proton, the measurement of magnetic fields, and most recently for medical diagnostics.
The magnet has been modified and adjusted to produce a highly homogeneous magnetic field over a relatively large volume (~1.5 cm^3) at the center of the gap.
Observe the behavior of the pattern as the RF level is varied, as frequency is varied, as the DC magnetic field is varied slightly, as the RF coil is moved away from the center of the gap, and as the modulating field amplitude and frequency are varied.
www.cco.caltech.edu /~derose/labs/exp5.html   (2248 words)

  
 Standard Model Challenged in a Magnetic Moment   (Site not responding. Last check: 2007-10-08)
The muon has a magnetic moment, which is equivalent to saying it has a north and south pole just like a bar magnet or a compass.
The north and south poles of the muon magnet are aligned along the direction of the spin.
The strength of the magnet is indicated by the magnitude of the magnetic moment.
www.pnl.gov /energyscience/03-01/art2.htm   (1029 words)

  
 Classical Orbital Magnetic Moment   (Site not responding. Last check: 2007-10-08)
where the term is dropped because it is negligible [135], the vector potential,, is expressed in terms of the magnetic field,, as, and use is made of the vector relation.
The magnetic interaction energy is thus defined as the dot product of the magnetic moment and the magnetic field, which expresses the physical fact that the energy is minimized when the magnetic moment and the external field are aligned (i.e.
In the case of the negatively charged electron, the minimum of the energy is when the magnetic moment and angular momentum are anti-aligned.
hep.bu.edu /~brown/phd/node78.html   (166 words)

  
 Physics 202
The magnetic moment is antiparallel to the magnetic field.
In a region of nonuniform magnetic field, say near a pole of an external magnet, the "pole" of the diamagnetic moment nearest the external pole is of the same sign and the atom is repelled, like the Al jumping ring.
Generally, the direction of the magnetization is different in different microscopic domains of material but a rather weak external field will cause complete alignment.
www.physics.wisc.edu /undergrads/courses/phys202fall96/Phys202_Magnetism.html   (542 words)

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