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Encyclopedia > Magnetic susceptibility

In physics and electrical engineering, the magnetic susceptibility is the degree of magnetization of a material in response to an applied magnetic field. The dimensionless volume magnetic susceptibility, represented by the symbol  chi_{v} (also represented in the literature by κ or Κ), is defined by the relationship Physics (Greek: (phúsis), nature and (phusiké), knowledge of nature) is the science concerned with the discovery and understanding of the fundamental laws which govern matter, energy, space, and time and explaining them using mathematics. ... Electrical Engineers design power systems… … and complex electronic circuits. ... Magnetization is a property of some materials (e. ... Current (I) flowing through a wire produces a magnetic field () around the wire. ...

mathbf{M} = chi_{v} mathbf{H}

where

M is the magnetization of the material (the magnetic dipole moment per unit volume), measured in amperes per meter, and
H is the applied field, also measured in amperes per meter.

The magnetic induction B is related to H by the relationship In physics, the ampere (symbol: A, often informally abbreviated to amp) is the SI base unit used to measure electrical currents. ... The metre, or meter (symbol: m) is the SI base unit of length. ...

mathbf{B}  =  mu_0(mathbf{H} + mathbf{M})  =  mu_0(1+chi_{v}) mathbf{H}  =  mu mathbf{H}

where μ0 is the permeability of free space (see table of physical constants), and  (1+chi) is the relative permeability of the material. Note that this definition is according to SI conventions. However, many tables of magnetic susceptibility give cgs values that rely on a different definition of the permeability of free space. The cgs value of susceptibility is multiplied by 4π to give the SI susceptibility value. For example, the cgs volume magnetic susceptibility of water at 20°C is -7.19x10-7 which is -9.04x10-6 using the SI convention. // ... Cover of brochure The International System of Units. ... This article or section is in need of attention from an expert on the subject. ... Cover of brochure The International System of Units. ... This article or section is in need of attention from an expert on the subject. ... Cover of brochure The International System of Units. ...


There are two other measures of susceptibility, the mass magnetic susceptibility in cm3•g-1 (χ or χg) and the molar magnetic susceptibility (χm) in cm3mol-1 that are defined as follows where ρ is the density in g•cm-3 and M is molar mass in g•mol-1. Molar mass is the mass of one mole of a chemical element or chemical compound. ...

χg = χv / ρ
χm = Mχg = Mχv / ρ

If χ is positive, then (1+χ) > 1 and the material is called paramagnetic. In this case, the magnetic field is strengthened by the presence of the material. Alternatively, if χ is negative, then (1+χ) < 1, and the material is diamagnetic. As a result, the magnetic field is weakened in the presence of the material. Paramagnetism is the tendency of the atomic magnetic dipoles, due to quantum-mechanical spin, in a material that is otherwise non-magnetic to align with an external magnetic field. ... Diamagnetism is a very weak form of magnetism that is only exhibited in the presence of an external magnetic field. ...


Volume magnetic susceptibility is measured by the force change felt upon the application of a magnetic field [1]. Early measurements were made using the Gouy method where a sample is hung between the poles of an electromagnet. The change in weight when the electromagnet is turned on is proportional to the susceptibility. Today, high-end measurement systems use a superconductive magnet. An alternative is to measure the force change on a strong compact magnet upon insertion of the sample. This system, widely used today, is called the Evan's balance. For liquid samples, the susceptibility can be measured from the dependence of the NMR frequency of the sample on its shape or orientation[2][3][4]. The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... Pacific Northwest National Laboratorys high magnetic field (800 MHz, 18. ...


The magnetic susceptibility of a ferromagnetic substance is not a scalar. Response is dependent upon the state of sample and can occur in directions other than that of the applied field. To accommodate this, a more general definition using a tensor derived from derivatives of components of M with respect to components of H Ferromagnetism is a phenomenon by which a material can exhibit a spontaneous magnetization, and is one of the strongest forms of magnetism. ... In mathematics, a tensor is (in an informal sense) a generalized linear quantity or geometrical entity that can be expressed as a multi-dimensional array relative to a choice of basis; however, as an object in and of itself, a tensor is independent of any chosen frame of reference. ... In mathematics, a derivative is the rate of change of a quantity. ...

chi_{ij} = frac{part M_j}{part H_i}

called the differential susceptibility describes ferromagnetic materials, where i and j refer to the directions (e.g., x, y and z in Cartesian coordinates) of the applied field and magnetization, respectively. The tensor is thus rank 2, dimension (3,3) describing the response of the magnetization in the j-th direction from an incremental change in the i-th direction of the applied field. Ferromagnetism is a phenomenon by which a material can exhibit a spontaneous magnetization, and is one of the strongest forms of magnetism. ...


When the coercivity of the material parallel to an applied field is the smaller of the two, the differential susceptibility is a function of the applied field and self interactions, such as the magnetic anisotropy. When the material is not saturated, the effect will be nonlinear and dependent upon the domain wall configuration of the material. In material science, the Coercivity of a ferromagnetic material is the intensity of the magnetic field required to reduce the magnetization of that material to zero after the magnetization of the sample has reached saturation. ... A domain wall is a theoretical 2-dimensional singularity. ...


When the magnetic susceptibility is studied as a function of frequency, the permeability is a complex quantity and resonances can be seen. In particular, when an ac-field is applied perpendicular to the detection direction (called the "transverse susceptibility" regardless of the frequency), the effect has a peak at the ferromagnetic resonance frequency of the material with a given static applied field. Currently, this effect is called the microwave permeability or network ferromagnetic resonance in the literature. These results are sensitive to the domain wall configuration of the material and eddy currents. Ferromagnetic resonance, or FMR, is a spectroscopic technique to probe the magnetization of ferromagnetic materials. ... A domain wall is a theoretical 2-dimensional singularity. ... An eddy current is a phenomenon caused by a moving magnetic field intersecting a conductor or vice-versa. ...


In terms of ferromagnetic resonance, the effect of an ac-field applied along the direction of the magnetization is called parallel pumping. Ferromagnetic resonance, or FMR, is a spectroscopic technique to probe the magnetization of ferromagnetic materials. ...


The magnetic susceptibility and the magnetic permeability (μ) are related by the following formula: This article is in need of attention. ...

mu = mu_0(1+chi) ,

where  (1+chi) is the relative permeability of the material.


Examples

Magnetic susceptibility of some materials
Material χm Tc
vacuum 0
water -1.2*10-5
Bi -16.6*10-5
C -2.1*10-5
0.19*10-5
Al 2.2*10-5
Fe 200 774°C
Co 70 1131°C
Ni 110 372°C

The Curie point is a term in physics and materials science, named after Pierre Curie (1859-1906), and refers to a characteristic property of a ferromagnetic material. ... Look up Vacuum in Wiktionary, the free dictionary. ... Impact of a drop of water. ... General Name, Symbol, Number bismuth, Bi, 83 Chemical series poor metals Group, Period, Block 15, 6, p Appearance lustrous reddish white Atomic mass 208. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Atomic mass 12. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Atomic mass 26. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... The degree Celsius (°C) is a unit of temperature named after the Swedish astronomer Anders Celsius (1701–1744), who first proposed a similar system in 1742. ... This article or section does not cite its references or sources. ... The degree Celsius (°C) is a unit of temperature named after the Swedish astronomer Anders Celsius (1701–1744), who first proposed a similar system in 1742. ... General Name, Symbol, Number nickel, Ni, 28 Chemical series transition metals Group, Period, Block 10, 4, d Appearance lustrous, metallic and silvery with a gold tinge Atomic mass 58. ... The degree Celsius (°C) is a unit of temperature named after the Swedish astronomer Anders Celsius (1701–1744), who first proposed a similar system in 1742. ...

See also

In electromagnetism, Maxwells equations are a set of equations, developed in the latter half of the nineteenth century by James Clerk Maxwell. ... Current (I) flowing through a wire produces a magnetic field () around the wire. ... Current flowing through a wire produces a magnetic field (B, labeled M here) around the wire. ... It has been suggested that this article or section be merged into permittivity. ... The Curie constant appears in Curies law, which relates the magnetic field and the temperature to the magnetisation of a paramagnetic substans. ... A magnetometer is a scientific instrument used to measure the strength and/or direction of the magnetic field in the vicinity of the instrument. ... Paleomagnetism refers to the orientation of the Earths magnetic field as it is preserved in various magnetic iron bearing minerals throughout time. ... Magnetic lines of force of a bar magnet shown by iron filings on paper In physics, magnetism is one of the phenomena by which materials exert an attractive or repulsive force on other materials. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ...

Notes

  1. ^ L. N. Mulay in Techniques of Chemistry, eds. A. Weissberger and B. W. Rossiter, Wiley-Interscience, New York, 4, 431 (1972)
  2. ^ J.R. Zimmerman, M.R. Foster, J. Phys. Chem. 61 (1957) 282-289; R. Engel, D. Halpern, S. Bienenfeld, Anal. Chem., 45 (1973) 367-369
  3. ^ P.W. Kuchel, B.E. Chapman, W.A. Bubb, P.E. Hansen, C.J. Durrant, M.P. Hertzberg, Conc. Magn. Reson. A 18 (2003) 56-71
  4. ^ K. Frei, H.J. Bernstein, J. Chem. Phys. 37 (1962) 1891-1892; R.E. Hoffman, J. Magn. Reson. 163 (2003) 325-331

  Results from FactBites:
 
Magnetic susceptibility - Wikipedia, the free encyclopedia (739 words)
In electrical engineering, the magnetic susceptibility is the degree of magnetization of a material in response to an applied magnetic field.
In this case, the magnetic field is strengthened by the presence of the material.
The magnetic susceptibility of a ferromagnetic substance is not a scalar.
Permeability (electromagnetism) - Wikipedia, the free encyclopedia (333 words)
In electromagnetism, permeability is the degree of magnetization of a material that responds linearly to an applied magnetic field.
Magnetic permeability is represented by the symbol μ.
If one puts the ferromagnetic material into an externally applied magnetic field, the domains tend to line up, so that the sum of the fields from the ferromagnet and the applied magnetic field is higher in magnitude than the applied magnetic field alone.
  More results at FactBites »

 
 

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