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Topic: Magnetic permeability

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Henry (inductance)

Magnetic flux density

Siemens (unit)

Current density

Inductance

Magnetic susceptibility

Permittivity

Magnetism

Reluctance

Electrical conductivity

Magnetic helicity

Electromagnetism

Diamagnetism

Magnetic field

SI

	Magnetic permeability of magnetic shields a critical factor
		It is defined as the ratio of the intensity of induced magnetization in the material to the intensity of the inducing magnetic force field that produced it.
		For the most effective magnetic shield attenuation performance, the higher the magnetic permeability, the better.
		Magnetically "hard" materials, on the other hand, make good magnets because they can retain a strong magnetic field even after the source of the magnetic energy has been removed.
	www.magnetic-shield.com /faq/pma.html (1086 words)

	MAGNETIC PERMEABILITY - Online Information article about MAGNETIC PERMEABILITY (Site not responding. Last check: )
		permeability is regarded as a pure number, and its value in empty space is taken as unity.
		As the force increases from zero the permeability of a given specimen rises to a maximum, which may amount to several thousands, and then gradually falls off, tending to become unity when the force is increased without limit.
		constant permeability, which differs from unity only by a very small fraction; if the substance is paramagnetic, its permeability is a little greater than 1; if diamagnetic, a little less.
	encyclopedia.jrank.org /PAS_PER/PERMEABILITY_MAGNETIC.html (342 words)

	Magnetic Permeability - LoveToKnow 1911
		The permeability of a metal belonging to the ferromagnetic class - iron, nickel, cobalt and some of their alloys - is a function of the magnetic force, and also depends upon the previous magnetic history of the specimen.
		As the force increases from zero the permeability of a given specimen rises to a maximum, which may amount to several thousands, and then gradually falls off, tending to become unitywhen the force is increased without limit.
		It is generally of importance that the iron employed in the construction of electrical machinery should possess high permeability under the magnetic force to which it is to be subjected.
	www.1911encyclopedia.org /Magnetic_Permeability (245 words)

	Permeability
		In SI units, magnetic flux density is measured in tesla, magnetic field strength in ampere per metre and permeability in henrys per metre.
		In geology, permeability is a measure of the ability of a material (typically, a rock) to transmit fluids.
		For a rock to be considered as an exploitable hydrocarbon reservoir, its permeability must be greater than approximately 100 md (depending on the nature of the hydrocarbon - gas reservoirs with lower permeabilities are still exploitable because of the lower viscosity of gas with respect to oil).
	www.ebroadcast.com.au /lookup/encyclopedia/ma/Magnetic_permeability.html (240 words)

	Tengam Engineering, Inc. ::: Magnetic Glossary
		The magnetic field induced by a field strength, H. It is the vector sum, of each point within the substance, of the magnetic field strength and resultant intrinsic induction.
		Magnetic induction is the flux per unit area normal to the direction of the magnetic path.
		The north pole of a magnet, or compass, is attracted toward the north geographic pole of the earth (which is actually, by definition, a magnetic south pole), and the south pole of a magnet is attracted toward the south geographic pole of the earth.
	www.tengam.com /html/magnetic.html (1783 words)

	Stainless Steel - Magnetic Properties
		Magnetic permeability is the ability of a material to carry magnetism, indicated by the degree to which it is attracted to a magnet.
		All austenitic grades have very low magnetic permeabilities and hence show almost no response to a magnet when in the annealed condition; the situation is, however, far less clear when these steels have been cold worked by wire drawing, rolling or even centreless grinding, shot blasting or heavy polishing.
		If magnetic permeability is a factor of design or is incorporated into a specification, this should be clearly indicated when purchasing the stainless steel from a supplier.
	www.azom.com /details.asp?ArticleID=1140 (492 words)

	Arnold - Glossary of Terms - (P)
		In the cgs system, the flux density in a vacuum is numerically equal to the magnetizing force and, consequently, the magnetic permeability is numerically equal to the ratio of the flux density to the magnetizing force.
		Note: In a non-isotropic (anisotropic) medium the permeability is a function of the orientation of the medium, since, in general, the magnetizing force and the magnetic flux are not parallel.
		Free space permeability is an arbitrary constant used with relative permeability to define the magnetic field (magnetizing force), H, and account for the contribution of a magnetic material to total flux density.
	www.arnoldmagnetics.com /mtc/glossary/glossary_p.htm (837 words)

	High Permeability Materials - Microwave Encyclopedia - Microwaves101.com
		Permeability is a magnetic property of a material, and is often expressed as
		It depends on many many factors like annealing and crystalline structure, but typically, for all ferromagnetic materials we measure permeabilities between 1 and 10000 or more, depending on their magnetic state (which is a function of its history and applied field).
		Permeability is as much a property of the material's grain structure as it is a bulk property.
	www.microwaves101.com /encyclopedia/highpermeability.cfm (754 words)

	High magnetic permeability composites containing fibers with ferrite fill - Patent 4725490
		The composite of claim 2 wherein the magnetic permeability of the ferrite is between 10 and 100 in the frequency range of 100 MHz to 1000 MHz, and wherein the aspect ratio of the fibers is at least 50.
		In this arrangement, the magnetic permeability of the ferrite may be between 10 and 100 in the frequency range of 100 MHz to 1000 MHz and the aspect ratio of the fibers is preferably at least 50.
		In order to estimate the effective permeability of an oriented array of fibers (such as a fabric, laminate or composite), the contribution to the magnetic permeability will be separated into that which is due to fibers aligned with the magnetic field and that which is due to fibers oriented perpendicular to the magnetic field.
	www.freepatentsonline.com /4725490.html (4266 words)

	PowerPedia:Magnetic field - PESWiki
		is the magnetic permeability of the medium, measured in henries per metre.
		The "north" and "south" poles of a magnet or a magnetic dipole are labelled similarly to north and south poles of a compass needle.
		Magnetic field density, otherwise known as magnetic flux density, is essentially what the layman knows as a magnetic field —akin to a gravitational or electric field.
	peswiki.com /index.php/PowerPedia:Magnetic_field (3059 words)

	Magnetic element and method of manufacturing magnetic element patent invention
		The magnetic element includes a coil (30) formed of a conductor having an insulating film, a first core member (20) constituted of insulative soft magnetic ferrite and covering the coil (30), and a second core member (50) having soft magnetic metal powder as material and surrounded by the first core member (20).
		However, when a material having high magnetic permeability such as ferrite is arranged, magnetically saturation can easily occur, and inversely, the magnetic permeability decreases at a predetermined current value or larger, which finally becomes equal to that of an air-core coil.
		Thus, the magnetic permeability of a material to be arranged should be suppressed to a certain degree.
	www.freshpatents.com /Magnetic-element-and-method-of-manufacturing-magnetic-element-dt20060824ptan20060186979.php (1391 words)

	Glossary of Magnet Terminology
		This is the point at which the hysteresis loop crosses the B axis at zero magnetizing force, and represents the maximum flux output from the given magnet material.
		Magnetic Field Strength (H) - Magnetizing or demagnetizing force, is the measure of the vector magnetic quantity that determines the ability of an electric current, or a magnetic body, to induce a magnetic field at a given point; measured in Oersteds.
		Relative Permeability - The ratio of permeability of a medium to that of a vacuum.
	www.kjmagnetics.com /glossary.asp (2435 words)

	Glossary of Magnet Terminology
		This is the point at which the hysteresis loop crosses the B axis at zero magnetizing force, and represents the maximum flux output from the given magnet material.
		Magnetic Field Strength (H) - Magnetizing or demagnetizing force, is the measure of the vector magnetic quantity that determines the ability of an electric current, or a magnetic body, to induce a magnetic field at a given point; measured in Oersteds.
		Relative Permeability - The ratio of permeability of a medium to that of a vacuum.
	kjmagnetics.com /glossary.asp (2435 words)

	Arnold - Glossary of Terms - (P)
		In the cgs system, the flux density in a vacuum is numerically equal to the magnetizing force and, consequently, the magnetic permeability is numerically equal to the ratio of the flux density to the magnetizing force.
		Note: In a non-isotropic (anisotropic) medium the permeability is a function of the orientation of the medium, since, in general, the magnetizing force and the magnetic flux are not parallel.
		Free space permeability is an arbitrary constant used with relative permeability to define the magnetic field (magnetizing force), H, and account for the contribution of a magnetic material to total flux density.
	www.grouparnold.com /mtc/glossary/glossary_p.htm (837 words)

	Magnetic Separators Manufacturer,Electromagnetic Separators,Suspended Electromagnetic Separators,Suspended Magnetic ...
		Erich magnetic pulley is a widely used type of magnetic separator for the efficient removal of tramp iron.
		Magnets are covered with aluminum or stainless steel shell and are bolted to heavy duty stainless steel end flanges and mounted to a sheet shaft.
		Permanent Magnetic Tubes and Grids: Erich permanent magnetic grids are designed primarily for hoppers for the extraction of ferrous metals from free flowing materials such as plastics, food,grains, and minerals.
	www.erichmagnetic.com /magnetic-separators.html (572 words)

	Magnetic Particles
		High magnetic permeability is important because it makes the particles attract easily to small magnetic leakage fields from discontinuities, such as flaws.
		Dry magnetic particles can typically be purchased in red, fl, gray, yellow and several other colors so that a high level of contrast between the particles and the part being inspected can be achieved.
		The wet magnetic particle testing method is generally more sensitive than the dry because the suspension provides the particles with more mobility and makes it possible for smaller particles to be used since dust and adherence to surface contamination is reduced or eliminated.
	www.ndt-ed.org /EducationResources/CommunityCollege/MagParticle/Equipment/Particles.htm (802 words)

	Oilfield Glossary: Term 'permeability'
		Effective permeability is the ability to preferentially flow or transmit a particular fluid through a rock when other immiscible fluids are present in the reservoir (for example, effective permeability of gas in a gas-water reservoir).
		Relative permeability is the ratio of effective permeability of a particular fluid at a particular saturation to absolute permeability of that fluid at total saturation.
		In magnetics, the ratio of the density of the magnetic flux, B (in units of teslas), to the strength of the magnetic field, H (in units of amperes/meter), typically in units of H/m.
	www.glossary.oilfield.slb.com /Display.cfm?Term=permeability (323 words)

	What is Magnetic Shielding?
		The most effective magnetic shielding material available is mu-metal, an alloy of 77% nickel, 16% iron, 5% copper, and 2% chromium, which is then annealed in a hydrogen atmosphere to increase its permeability.
		Magnetic shielding is often employed in hospitals, where devices such as magnetic resonance imaging (MRI) equipment generate powerful magnetic flux.
		Magnetic shielding using superconducting magnets is being researched as a means of shielding spacecraft from cosmic radiation.
	www.wisegeek.com /what-is-magnetic-shielding.htm (468 words)

	Magnetic fields (HSG 27, 1989)
		In the case of static magnetic fields, protection limits tend to be stated primarily in terms of the external field strength, or magnetic flux density, and the duration of exposure.
		Magnetic flux density is used to describe the magnetic field generated by electric currents in a conductor.
		The magnetic field strength (H) is related to the magnetic flux density (B) by the equation: B = µH Thus, the magnetic field is defined as a vector field of magnetic flux densityB (B-field).
	www.inchem.org /documents/hsg/hsg/hsg027.htm (3190 words)

	Ferromagnetism
		The fraction of the saturation magnetization which is retained when the driving field is removed is called the remanence of the material, and is an important factor in permanent magnets.
		The microscopic evidence about magnetization indicates that the net magnetization of ferromagnetic materials in response to an external magnetic field may actually occur more by the growth of the domains parallel to the applied field at the expense of other domains rather than the reorientation of the domains themselves as implied in the sketch.
		Keep in mind the fact that the internal magnetic fields which come from the long range ordering of the electron spins are much stronger, sometimes hundreds of times stronger, than the external magnetic fields required to produce these changes in domain alignment.
	hyperphysics.phy-astr.gsu.edu /hbase/solids/ferro.html (1076 words)

	Magnetic properties of materials
		However, the magnetic moments in one direction are weaker than the moments in the opposite direction leading to an overall magnetic moment.
		This means that the permeability must also be lower during 'charge up' than it is during 'relaxation', even for the same value of H. In the extreme case of a permanent magnet the permeability within it will be negative.
		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 (3941 words)

	Circular Magnetic Fields
		The magnetic field is zero at the inside wall surface and rises until it reaches a maximum at the outside wall surface.
		As with a solid conductor, when the conductor is a magnetic material, the field strength within the conductor is much greater than it was in the nonmagnetic conductor due to the permeability of the magnetic material.
		The magnetic field distribution in and around a nonmagnetic central conductor carrying DC inside a hollow conductor of a magnetic material.
	www.ndt-ed.org /EducationResources/CommunityCollege/MagParticle/Physics/CircularFields.htm (768 words)

	[No title]
		Since the magnetic response due to the target permeability is small relative to the response due to the target resistivity the target permeability does not significantly detract from the determination of an accurate resistivity distribution via inversion.
		Since the permeability response occurs coincident with the body, and it is modest with respect to responses due to the resistivity distribution, it is concluded that moderate magnetic permeability within an MMR/ERT survey area is not immediately significant to the development of the joint MMR/ERT technology.
		These include preliminary or concurrent inversion for magnetic permeability, mapping and modeling of known permeable objects, performance of a magnetic survey using the earth’s magnetic field, performance of a magnetic survey using another known magnetic field or a combination of the these methods.
	www.geology.wisc.edu /~maludwig/Conclusions.doc (573 words)

	MuShield Magnetic Shielding - Frequently Asked Questions
		When magnetic lines of flux encounter high permeability material, the magnetic forces are both absorbed by the material and redirected away from its target, much as a beavers dam absorbs and reroutes water from its den.
		The rounded surface of the cylinder is conducive to the absorption of magnetic flux.
		Since a magnetic shield functions by providing a low reluctance flux path, and magnetic flux flows from its north pole to the south pole, a flat sheet will only cover a portion of the flux path.
	www.mushield.com /faq.html (1193 words)

	Magnetic engineering - Permeability of rare earth magnets
		The flux density of a permanent magnet is significantly dependent on the geometry of the magnet.
		Magnet design engineers use some reasonably good approximations of the flux generated by a magnet, by taking into account the ratio of the surface area of one pole of the magnet [basically half the surface area for a rare earth rectangle, for example], to the cross-section of the magnet through which flux is flowing.
		UKpete, you didn't explain why, at unit relative permeability, the magnet thickness is not accounted for in the air gap, and also in what respect Alnico magnets behave differently from RE from the point of view of the magnetic circuit (that is not considering the very different demagnetization curves).
	www.eng-tips.com /viewthread.cfm?qid=98210&page=8 (977 words)

	Carpenter Technology Corporation - A Simplified Method of Selecting Soft Magnetic Alloys
		Permeability is a ratio of the magnetic induction output (B) to the magnetic field strength input (H) that produced the induction.
		Their relative permeability (as well as strength and cost) is shown by color code with that of the other alloy families in Fig.
		Chrome Core® 8 and 8-FM alloys, and Chrome Core 12 and 12-FM alloys have been used for magnetic components where corrosion resistance superior to that of pure iron, low carbon steel and silicon-iron alloys is desired with a slight decline in saturation induction properties.
	crswnew.cartech.com /wnew/techarticles/TA00005.html (2645 words)

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