ECN Forum Forums Photo Discussion Forums Photos for General Discussion Gizmos

Alan,
Take one of those magnets and drop it through a vertical length of copper tubing that has an ID just slightly larger than the OD of the magnet.
Don

Don,
A 1/2" (12.7mm) diameter x 1/2" long magnet took 25 seconds to fall through 5 ft of 14mm bore ( metric ) copper tube, a loose fit. What's happening here?
Got the magnet out of the file cabinet by sliding it onto a thin aluminum plate and levering it off.
Alan

Lentz's law is as work here. The moving magnet induces current in the copper pipe, the magnetic field from this current is such that it repels the dropping magnet and causes it to defy gravity. Try it with a length of aluminum conduit. The same effect will be there but because aluminum is not as good of conductor as copper the amount of current produced it less and the magnet will fall faster.
I got 29 seconds for the 1/2 x 1/2 magnet in a 5' length of 1/2" type L copper pipe(0.545", 13.83mm ID).
Don



[This message has been edited by resqcapt19 (edited 06-16-2005).]

EMF..........


what is really neat is play with a speaker coil and a a strong magnet with skill you can make the coil "float" for several seconds.

Before embarking on more jolly experiments with NdFeB magnets, check out-
http://www.wondermagnet.com/crush.html

Also, click on the header, and read the safety warnings.

Play safe,
Alan

To combine Gizmos and Magnets, a buddy of mine dropped a mini tubing cutter down a 3" steel support pipe. Sending a magnet down on a string was out of the question, so I sleeved a piece of schedual 80 over the outside, and tied seperate strings to the magnet and the conduit. The sleeve kept the magnet from sticking to the steel pipe until the whole shebang reached the bottom, then I could drop the magnet down the inside of the sleeve until I heard it hit the tubing cutter. Pull everything back up easy as you please.

Those neodymium magnets are great!

-John