Experiments with Magnetic Fluid

A permanent magnet providing a vertical magnetic field is placed under a container with magnetic fluid. In fig 1 the distance is still a few cm so that the field is just abot 100kA/m at the surface of the fluid.

In this case the Rosensweig resonance can be observed. The magnetized material starts to aglign along the field lines in vertical direction. The peaks lift up from the surface to get in line with the field. At the same time the peaks are repelling other material that has the same orientation in neighbouring peaks.

In this way a 2-dimensional structure of peaks is formed that is characterisic for the field strength and the concentration of the magnetic fluid.

In the following video the behavior of magnetic fluid is compared with the behavior of a few steel balls in the same magnetic field, they behave quite similar.


fig 1
fig 2
From fig 2 the container is placed directly onto the magnet and the tip of a strong electical magnet above the container is added. In fig 2 the field from above is still small pointing into the same dirction a the field from the permanent magnet below. This can be verified by the orientation of the inner peaks pointing to the tip of the electric magnet.

When more of the magnetic fluid is attached to the tip of the electric magnet a bridge connects the tip with the container fig 3.

Increasing the magnetic field from above intensifies the connection, fig 4. It can be observed that the bridge is intensified and it is split into three magnetic links that have the same orientation and that are repelling each other.

fig 3
fig 4
In fig 5 the field of the elecromagnet is reveresed pushing away the peaks formed by the permantent magnet below.

In fig 6 the the clearing of the inner field of the conttainer can be observed. Small heaps of remaining magnetic material ar formed migrating to the side.

fig 5
fig 6