Eddy currents?

Question

An eddy current (also known as Foucault current) is an electrical phenomenon discovered by French physicist Léon Foucault in 1851. It is caused when a conductor is exposed to a changing magnetic field due to relative motion of the field source and conductor; or due to variations of the field with time. This can cause a circulating flow of electrons, or a current, within the conductor. These circulating eddies of current create electromagnets with magnetic fields that opposes the change of the magnetic field (see Lenz's law). The stronger the applied magnetic field, or greater the electrical conductivity of the conductor, or greater the relative velocity of motion, the greater the currents developed and the greater the opposing field.

Can someone pleas translate this into laymens terms i would like to try to build one any ideas on this would be greatly appreciated.

Answer 1

You want to build an eddy current??

What it means is that a conductor (eg. lump of metal) moving through a magnetic field becomes an electromagnet. The magnetic field from the conductor always has opposite polarity to the static magnetic field.

There are some nice demonstrations of this phenomenon, which is also known as magnetic braking. Have a look here:

http://amasci.com/amateur/neodymium.html...

The best demo of this I ever saw was in an experimental 3 Tesla MRI scanner. The field inside these machines is extremely strong. The clinical scanners have shielding which reduces the field around the scanner, but this one had no shielding. You stand near the scanner holding a 12" square piece of aluminium upright, by its edge, then you release your grip on it. It falls over, but veeeery slowly.