5G20.73 - Electromagnetic Levitator - Suspended Globe

Code Number:
5G20.73
Demo Title:
Electromagnetic Levitator - Suspended Globe
Condition:
Excellent
Principle:
Eddy Currents
Area of Study:
Electricity & Magnetism
Equipment:
Levitating 8 inch world globe. Homemade Levitation Apparatus with a magnet on a small bolt or battery.
Procedure:

This apparatus is unique in that the magnetic platform can be placed inside the globe, used by itself, or you can place something as heavy as 12 oz. on the platform.  Also, with the stand attachment, you can turn the base on its side and the platform will still remain in place.  If everything is balanced correctly the globe/platform will slowly rotate.

The small globe will float above the curved plate when positioned correctly.  This will not turn like the above globe.

Place the apparatus on the table and turn on the power.  Place the globe between the base and the top yolk of the demo and move gently up and down until you feel the globe is in equilibrium.  Let go and the globe should float in that position.  The base also has a mechanism for rotating the globe.  A gentle spin in the CCW direction is all that it necessary to start the globe in continuous spin mode.

Put a small magnet onto a battery with the pole orientation such that the magnet is attracted to the coil when the unit is on.  You will need to adjust the variable pot very carefully to find the sweet spot where the magnet/battery unit will float under the coil.  Complete directions for this unit are in the box in which the unit is stored.

References:
  • A. Cary, E. Mayfield, J. Mottmann, "A Toy 'Magnetometer'", TPT, Vol. 46, # 7, Oct. 2008, p. 437.
  • Horacio Munguia Aguilar, "Magnetic Levitation and Newton's Third Law", TPT, Vol. 45, # 5, May 2007, p. 278.
  • Harvey E. White and Hans Weltin, "Electromagnetic Levitator", AJP, Vol. 31, #12, Dec. 1963, p. 925.
  • Julien Clinton Sprott, "5.5 Levitated Ball", Physics Demonstrations,  p. 222, ISBN 0-299-21580-6.
  • Ron Hipschman, Recipe # 153 - "Suspense", Exploratorium Cookbook III, p. 153-1.


Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.