## Neodymium Magnet

2 11 2010

I received a neodymium ring magnet today with an eye towards a permanent magnet magrid.

This thing is wicked strong!

### 5 responses

3 11 2010

that’s wicked big for a neodymium magnet. looks like the class that have the disclaimer “this can cause physical injury….”

problem with permanent magnets is the field lines run right into them, and thus so will the electrons. you’ll have to be pumping in juice like crazy, like using a bucket to empty water from a ship with it’s hull ripped open.

3 11 2010

“the field lines run right into them”

Is this not the case with electromagnets?

3 11 2010

correct, it is not the case with electromagnetics.
permanent magnets use the orientation of the atoms in the magnet – the atoms are essentially _part of_ the field line. whereas electro-magnetics use the relationships of electric current and magnetic fields as described by maxwell’s equations: to put it informall: an electric current going in a straight line will induce a magnetic field that travels in a circle around the current. (likewise, a moving magnetic field induces an electric current with the same (but complementary) geometric relationship) going in a circle around means it never runs into. magnetic field lines are everywhere traverse to the current that induces it, and therefore can never intersect that current.

http://en.wikipedia.org/wiki/Electromagnetic_field

3 11 2010

of course!

What a subtle difference between a permanent magnet and electromagnet!

Thanks, you just saved me some money and time!

3 11 2010

compare here: http://en.wikipedia.org/wiki/Magnetic_dipole#Classification
the picture above (field created by a permanent magnet, aka atoms w/their charges aligned ) vs the picture below (field created by an electro-magnetic, aka a current ring). in the former _all_ field lines emminate from the the magnet, in the latter _none_ of them do.