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The surprising interactions between copper and neodymium magnets

Experiments with super strong neodymium magnets and copper! These surprising demonstrations of magnetic damping go beyond the magnet through a copper tube demo that we’ve previously seen. Watch as Night Hawk in Light explores a variety of ways that a “magnet’s momentum is slowed by opposing magnetic fields generated by the flow of electrons in the copper,” including magnetic braking and magnetic levitation. A bit more from wikipedia:

When a magnetic field moves through a conductor the movement induces an eddy current in the conductor. The flow of electrons in the conductor immediately creates an opposing magnetic field which results in damping of the magnet and produces heat inside the conductor similar to heat buildup inside of a power cord during use. The amount of energy transferred to the conductor in the form of heat is equal to the change in kinetic energy lost by the magnet – the greater the loss of kinetic energy of a magnet (a product of its mass and speed), the greater the heat buildup in the conductor and the more forceful the damping effect. Eddy currents induced in conductors are much stronger as temperatures approach cryogenic levels. This allows for critical damping for cryogenic applications and testing in the aerospace industry.

These look like awesome experiments to try at home or school. Please note these neodymium magnet hazards to help practice safe & smart science. Related reading: Magnetic flux, Lenz’s Law, and Faraday’s Law of Induction.

Watch more neodymium magnet videos, including DIY Ferrocell: How to make a magnetic field viewer, Electromagnetic Induction, and how to make simple homopolar motor ‘race cars’.

Also: Dropping a neodymium magnet through a thick copper pipe, which includes a video about how this phenomenon is related to English scientist Michael Faraday and the first electric generator, and lots of levitation videos.

via BoingBoing.

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