Levitating Ring - Lenz Law


This experiment demontruje electromagnetic levitation.

Educational phase: motivation


Required aids+

  • two aluminum ring
  • coil turns 300
  • I long core
  • 120V AC power pack
  • rheostat 40 Ω
  • connecting wires
  • switch key


Experiment schema+

Scheme author is Mgr. Karel Stibor

This experiment demontruje electromagnetic levitation.

Experiment instructions+

E122_S001 Assemble the circuit. The core is inserted into the coil and is fitted through the rheostat connected to an AC voltage. The coil is placed an aluminum ring serving as a secondary thread.
E122_S002 Closes switch key.
E122_S003 Ring Rockets and will levitate a few inches above the coil.
E122_S004 After switching off the power ring goes back to its original position.
E122_S005 When setting the high voltage switching and key ring flips.


In the ring when it begins to emerge around the magnetic field and the induced current, according to Lenz's law "in its effects for the change that caused it." Thanks to this mg. the reverse-oriented, as in the coil and the coil so it will repel each other and the ring. The ring is warm after a while, because it goes through quite a decent current.

Experiment video+

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Physical interpretation+

The direction of current induced in the ring describes Lenz's law: "The induced electric current in a closed circuit has such a direction that its magnetic field counteracts the change in magnetic flux, which is the cause (or caused by that stream)."


Ensure safety, ring is thrown very much!
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This experiment has been added 14.4.2012 by Jan Krejčí and since then have 19324 visits.
3.6.2014 21:44 © Krejčí Jan