Magnetostatics

Magnetostatics arises from the union of magneto + static. We first see it at the end of the 19th century by Arthur Gordon.

Magnetostatics is the branch of physics that studies magnetic fields that remain fixed over time. Magnetostatics encompasses everything from magnets to electromagnets.

There are different types of magnetostatics:

• Current or voltage-driven coil

• The current path and coil segments

• Permanent magnet

• Magnetic source field

• Stationary current field

Magnetostatic energy is the energy that is stored in the static field. However, magnetization does not mean that it is static, but that it is not easily altered.

Magnetostatic energy is created through the formation of domains. The energy per this unit volume E_m is:

-µ₀= the permeability in vacuum (4π10^-7 H/m)

The vector of m = unit momentum of the volume of the domain under the H field.

The vector of H = magnetic field of the domain.

This magnetostatic energy has the capacity to reduce to zero because of the structure coming from the domains which do not allow external magnetic flux.

Unlike electrostatics, magnetostatics is concerned with the study of magnetic fields in which the current is constant.

One of the most important applications of magnetostatics is the electric motor. This can be used in various household appliances. We can also find them in transformers, bells...

How are magnetic fields measured?

The measurement of magnetostatic fields is measured:

• Gouy's balance: this is an instrument that allows us to measure the magnetic susceptibility of a specific sample. This balance measures the weight at the moment when it is attracted by the magnetic field zone of the poles and the other at the moment when it is repelled, in order to compare them.

• Magnetometers: an instrument that helps us to measure both the direction and the strength of a magnetic field.

The magnetostatic equations allow us to know its behavior. That is why we can find the following magnetostatic laws:

The magnetization of square neodymium magnets is diametrically magnetized.

The most common application of magnetostatics, and the one we see most often, is in micro magnetism, in the form of a magnetic recording device.