Physics Demo Manual

Demonstrations are cataloged according to PIRA Bibliography

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Due to Physics Building renovations, the lead time to set up demo requests has increased due to the need to transport equipment across campus. Please be kind and let me know well ahead of time what you need.

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video - Eddy Current Tube

Purpose:

An illustration of the damping effects of eddy currents on the motion of a falling magnet near the conducting surface of a copper tube.

Procedure:

DEMO VIDEO DOWNLOAD

SETUP:

First one shows that a non-magnetic piece of aluminum metal does not attract and stick to a solid iron rod; whereas, a very strong neodymium magnet (RED denoting North) hops and sticks to the iron rod.
Now drop the piece of aluminum metal through the vertically oriented OFHC copper tube making sure to point out the time it takes for it to pass all the way through. Next, drop the neodymium magnet through. Eddy currents generated in the conductive wall of the copper tube damp the motion of the magnet causing it to take a much longer time to come out the bottom end.

Hints:

Make sure to use non-magnetic (aluminum or brass) clamps on the tube, otherwise the magnet will get "stuck". One might also use the auxiliary camera looking into the tube from the top and projected onto the screen.

Equipment:

Stand
Steel Ball
Small Cylindrical NiFeB Magnet
Copper Tube