It is a measure of the magnetization that a material obtains in response to an applied magnetic field. In general, permeability is not a constant value, as it can vary with the position in the medium, the frequency of the applied magnetic field, humidity, temperature, and other criteria.
In a nonlinear medium, the permeability can depend on the strength of the magnetic field. Permeability as a function of frequency also addresses real or complex values. A closely related property of materials is magnetic susceptibility, which is a dimensionless proportionality factor that indicates the degree of magnetization of a material in response to an applied magnetic field.
It is proportional to the dimensionless fine-structure constant with no other dependencies. Magnetic susceptibility is the degree to which a material can be magnetized in an external magnetic field. If the ratio between the induced magnetization and the inducing field is expressed per unit volume, volume susceptibility k is defined as.
Ferromagnetic materials do not have a constant relative permeability and vary from to Magnetic susceptibility is very high and positive and depends on the applied field. Iron, cobalt, nickel and their alloys are examples of ferromagnetic materials.
Diamagnetic susceptibility is a temperature independent quantity Fig. Hysteresis is the dependence of the state of a system on its history. For example, a magnet may have more than one possible magnetic moment in a given magnetic field, depending on how the field changed in the past. Hysteresis can be found in physics, chemistry, engineering, biology, and economics. A hysteresis loop shows the relationship between the induced magnetic flux density B and the magnetizing force H.
It is often referred to as the B-H loop. This is referred to as the point of retentivity on the graph and indicates the remanence or level of residual magnetism in the material. The magnetization of ferromagnetic substances due to a varying magnetic field lags behind the field. This effect is called hysteresis, and the term is used to describe any system in whose response depends not only on its current state, but also upon its past history.
Hysteresis is important for producing stable switching behavior in a comparator circuit. Noise on the input signal in a comparator circuit can produce multiple transitions as the input signal rises. Intentionally adding hysteresis to a comparator circuit is useful for suppressing this unintended switching due to noise.
When the desired effect of applying or removing voltage happens after a delay, this phenomenon is referred to as voltage hysteresis. Voltage hysteresis can happen in many electronic components and constructs, including batteries, comparators, circuits, and transformers. Different materials have different values for the magnetic susceptibility.
Paramagnetic materials have a magnetic susceptibility greater than zero whereas diamagnetic materials have a value less than zero. This means diamagnetic materials tend to get repelled from a magnetic field while a paramagnetic material is attracted to a magnetic field. The magnetic susceptibility of a material is given by the following relationship.
M is the magnetic moment per unit volume of the material and H is the intensity of the external magnetic field. Xm indicates magnetic susceptibility. Magnetic permeability is given by the units Henries per meter, and magnetic susceptibility is a dimensionless property of materials.
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