Your complete guide to magnetic terminology, principles, and definitions — by Eclipse Magnetics.
This glossary is designed to help you understand the most important terms and concepts used in magnetism, materials science, and magnetic engineering. Whether you’re new to magnet technology or refining your technical knowledge, this resource provides clear, concise explanations of key magnetic principles.
A–F: Core Magnetic Concepts
Air Gap
An air gap is the non-magnetic space in a magnetic circuit — the distance between two magnetic poles. This gap may include air, paint, or non-magnetic materials such as brass and aluminium. Air gaps play a crucial role in determining the magnetic circuit’s overall strength and efficiency.
Anisotropic Magnet
An anisotropic magnet has a preferred direction of magnetisation, meaning its magnetic strength is concentrated in one specific orientation. These magnets are stronger and more efficient than isotropic magnets when aligned correctly.
Closed Circuit
A closed magnetic circuit occurs when magnetic flux is contained within a continuous path of permeable materials, such as iron. This reduces magnetic leakage and improves overall efficiency.
Coercive Force (Hc)
The coercive force is the amount of magnetising field strength required to reduce a magnet’s magnetisation to zero. It measures a material’s resistance to demagnetisation and is expressed in Oersteds or A/m.
Curie Temperature (Tc)
The Curie temperature is the point at which a magnetic material loses its magnetism completely. Above this temperature, the atomic structure changes, preventing the alignment of magnetic domains.
Demagnetisation Curve (B–H Curve)
The demagnetisation curve represents how a magnet responds to external magnetic fields. It shows how the material retains or loses its magnetisation when exposed to opposing magnetic forces.
Ferromagnetic Material
Ferromagnetic materials, such as iron, nickel, and cobalt, are substances that can be strongly magnetised. They possess high magnetic permeability and form the foundation of most permanent magnets.
Flux
Magnetic flux refers to the total magnetic field passing through a given area. It’s measured in Webers or Maxwells.
Fringing Fields
Fringing fields describe the magnetic flux that spreads outward around the edges of a magnet or air gap. These fields can cause minor losses but are important in shaping the magnetic field distribution.
G–L: Measurement & Circuit Behaviour
Gauss
Gauss is a unit used to measure magnetic flux density. One Tesla equals 10,000 Gauss.
Hysteresis Loop
A hysteresis loop illustrates how a magnetic material gains, retains, and loses magnetism under alternating magnetic fields.
Induction (B)
Magnetic induction refers to the magnetic flux density within a material or area, expressed in Gauss or Tesla.
Intrinsic Coercive Force
This measures a magnet’s internal resistance to demagnetisation.
Irreversible Loss
Irreversible loss occurs when a magnet permanently loses performance due to heat, vibration, or strong demagnetising forces.
Isotropic Magnet
An isotropic magnet can be magnetised in any direction but is weaker than anisotropic magnets.
Knee of the Demagnetisation Curve
The point on the B–H curve where linear magnetisation stops.
Leakage Flux
Leakage flux is the portion of magnetic flux that escapes the magnetic circuit.
M–S: Key Technical Parameters
Length of Air Gap (Lg)
The total distance magnetic flux must cross within an air gap.
Load Line
A load line represents the magnet’s operating point on the B–H curve.
Magnetic Circuit
A magnetic circuit is a closed path that allows magnetic flux to flow through magnets, gaps, and ferromagnetic materials.
Magnetic Flux
The total quantity of magnetic field lines passing through a surface.
Magnetising Force (H)
The strength of the external magnetic field used to magnetise a material.
Magnetomotive Force (F)
The magnetic equivalent of voltage, driving flux through a circuit.
Maximum Energy Product (BH Max)
Represents the maximum magnetic energy stored in a magnet.
Oersted (Oe)
A unit of magnetic field strength.
Permeance Coefficient (Pc)
Also called the load line; the ratio of magnetic induction to demagnetising force.
Pull Gap
Measures how a magnet’s holding force decreases with increasing distance.
R–Z: Advanced Magnetic Terms
Remanence
Remanence refers to the remaining magnetic field in a magnet after the magnetising force is removed.
Residual Induction (Br)
The point where magnetic flux remains at maximum after magnetisation.
Return Path
The low-reluctance route through which magnetic flux completes its circuit.
Saturation
Saturation occurs when a magnetic material cannot increase magnetisation further, even under stronger external fields.
Stabilisation
Stabilisation is the controlled process of ensuring long-term magnetic stability when a magnet is exposed to temperature or reverse fields.
Conclusion
This glossary provides essential definitions for engineers, designers, and anyone working with magnetic materials or products. Understanding these concepts supports better design decisions, performance analysis, and product selection.