This version (2016/04/28 00:54) was approved by svrijn.The Previously approved version (2012/04/18 02:50) is available.Diff

Magnet in copper tube


A magnet dropped through a electrical conducting (copper) tube will fall slow, at constant speed.

Description of the Experiment

Drop a power full neodymium magnet through a vertical copper tube.

When the magnet falls in the gravitation field, through the tube, the acceleration is gone, so that the magnet falls with constant speed. This can bee confirmed by making the experiment with tubes of different length, and observe that the fall time is almost proportional to the length of the tube.

When the magnet falls through the tube, it will induce a current in the copper (you can think of the tube as a coil with only one turn). This current creates a magnetic field, which according to Lenz's law is directed opposite of the falling magnets field, which then is slowed down.

Be ware that you need a very powerfull magnet and a well fitting tube. This effect will dramatically drop if the experiment is carried out with a tube which has bin cut in a line in the length of the tube.

Safety Information

Very strong magnets can damage electrical equipment, like cellphones, cameras, and credit cards. Also they can hurt a small piece of skin, from the attraction to other magnets or magnetic materials, ex iron.

Equipment and materials

Power full magnet

Copper tube


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experiments/magnet_in_cobber_tube.txt · Last modified: 2016/04/28 00:54 by svrijn
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