Arnold - Glossary of Terms

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Glossary

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Faraday's Law
The law that defines the relationship of the voltage induced across the winding of a core to the flux density within the core.

Ferrites
A soft ferrite material that has lower permeability with very low eddy-current loss. The common ferrites are nickel-zinc, manganese-zinc and magnesium-zinc ferrite.

Ferromagnetism
Ferromagnetic materials have atomic fields that align themselves parallel with externally applied fields creating a total magnetic field much greater than the applied field. Ferromagnetic materials have permeabilities much greater than 1. Above the Curie temperature, the ferromagnetic materials become paramagnetic.

Filter Capacitor
A capacitor, quite often used in conjunction with an inductor, that filters unwanted frequencies by storing electrostatic energy.

Flux
In magnetics, the magnetic field. Flux implies flow which is not the case in magnetics. That is, no one has measured a magnetic "flow". Flux is represented conceptually as "magnetic lines of force". Flux density is measured in gauss or tesla.

Flux 0
In the special pulse test used to evaluate bobbin tape cores, this corresponds to B_m - B_r.

Flux 1
In the special pulse test used to evaluate bobbin tape cores, this corresponds to B_m + B_r.

Flux Density
Magnetic (B) - The fundamental magnetic force field. "Flux" means to flow (around a current carrying conductor, for example) and "density" refers to its use with an enclosed area and Faraday's Law to determine induced voltage. Also called the "induction field." From Faraday's Law, the MKSA unit of flux density is a volt-second per square meter per turn or "Tesla." (The CGS unit of magnetic flux density is the Gauss. There are 10,000 Gauss per Tesla).

Remanent or residual ~ - The flux density that remains in a magnetic material after an applied magnetic field (magnetizing force) is removed.

Saturation - This is the flux density of maximum material magnetization. Magnetization (M) is the contribution of a magnetic material to the total flux density.

B = ľ_o(H+M) in MKSA units.

B = H+4πM in CGS units.

Saturation magnetization is the maximum value of magnetization. Also, the term "saturation" is sometimes used as a reference to the decrease of permeability with increasing magnetizing force. In an inductor, this corresponds to a decrease of inductance with current.

Flux Transfer Ratio
The numeric ratio of the amount of flux intercepted by the secondary winding and the total flux created by the applied amp-turns.

Fluxmeter
An instrument that measures the change of flux linkage with a search coil. The current in the search coil caused by relative motion with the magnet is integrated (totalized). Using a calibrated coil allows calculation of field and magnet properties.

Flyback Transformer
A device that functions as an inductor and a transformer.

Fringing Fields; Fringing Flux
The field(s) associated with the divergence of the flux from the shortest path between poles in a magnetic circuit. Where flux passes from a high permeability into a lower permeability material, the flux redistributes. See also, Leakage Flux.