Magnetiseringsstyrka

Magnetiseringsstyrka, known in English as the magnetic field strength or magnetic induction, is a physical quantity that describes the intensity of a magnetic field produced by a magnetic source or current distribution. It is denoted by the symbol H in many contexts and measured in amperes per meter (A/m) in the International System of Units. In materials science, magnetiseringsstyrka is often distinguished from the magnetic flux density B, which incorporates the material’s magnetic permeability.

In the field of electromagnetism, magnetiseringsstyrka is defined as the field created by free currents and is independent of the material’s response. Its vector nature means that it is represented by both magnitude and direction. The relationship between H, B and the magnetic permeability μ of a medium is given by B = μH. Here, μ comprises both the vacuum permeability μ₀ and the relative permeability μᵣ of the material.

When studying magnetic materials, magnetiseringsstyrka plays a key role in hysteresis loops. The loop’s shape reflects how the material's magnetization M changes with H, revealing phenomena such as coercitivity, remanence and saturation magnetization. Engineers use this information to design transformers, inductors, and magnetic recording devices that rely on predictable magnetiseringsstyrka behavior.

In practice, magnetiseringsstyrka is calculated from the geometry of the source and the current flowing through it. For a long solenoid, the formula H = nI (where n is turns per meter and I the current) gives an easily measured field. For more complex shapes, numerical methods and simulation software often provide accurate H distributions.

Finally, magnetiseringsstyrka is a foundational concept in advanced physics and engineering. It connects Maxwell’s equations to material responses and underpins technologies ranging from energy transmission to biomedical imaging. Understanding its definition, units, and practical calculation is essential for anyone working with magnetic phenomena.