Magnetic Fields Bending Light Paths With Specular Reflection
Ferrofluid is a liquid that is attracted to the poles of a magnet. It is a colloidal liquid made of nanoscale ferromagnetic, or ferrimagnetic, particles suspended in a carrier fluid (usually an organic solvent or water). Each magnetic particle is thoroughly coated with a surfactant to inhibit clumping. Large ferromagnetic particles can be ripped out of the homogeneous colloidal mixture, forming a separate clump of magnetic dust when exposed to strong magnetic fields. The magnetic attraction of tiny nanoparticles is weak enough that the surfactant’s Van der Waals force is sufficient to prevent magnetic clumping or agglomeration. Ferrofluids usually do not retain magnetization in the absence of an externally applied field and thus are often classified as « superparamagnets » rather than ferromagnets. (Learn more : https://en.wikipedia.org/wiki/Ferrofluid )
In this video I show you how a magnet and ferrofluid can be used to change the orientation of iron particles. The iron nanoparticles can reflect LED lights through specular reflection. Though this device does not show magnetic fields it can show you the effect of the magnetic field on the position of the iron particles.