Undeniable Friday

Update: Here's a zipped version of the video

It's Undeniable Friday! Every Friday, in addition to an odd little factoid, UndeniableFacts.com gives you a fun puzzle, illusion, or activity to enjoy and share.

Today: "The Levitating Screw"

The Levitating Screw is a great trick to do at parties. All you need are two (fairly strong) magnets, a screw, a lime, a coil of copper wire, and a cup of salt water.

By arranging these components correctly, you can make the screw levitate several inches in the air, spinning wildly, for several seconds.

Here is a video of the Levitating Screw in action:





How to do it:

First, hold one of the magnets (I prefer to use long bar magnets for this trick) in each hand. Turn the one in your right hand so that the North pole faces you. Turn the one in your left hand so that the South pole faces you. Now, place them on a flat surface so that they are just far enough apart that they do not pull each other together.

Now, place the coiled wire between the two magnets. It should look like a stretched out spring, parallel to the magnets. Place a small container of salt water at one end of the coil, and place the end of the coil in the water. Put the lime at the other end of the coil and put that end of the coil in the lime.

Now, carefully place the screw directly above the center of the spring, a few inches up. If done correctly, the screw will dance around in the air fo