Magnetic Levitation

The concept of using magnetic fields to suspend objects in the air is not a new concept but one that deserves attention. While this can be achieved by using traditional magnets, higher efficiencies and lower temperatures can be achieved by using a superconductor. Discovered by Dutch physicist Heike Kamerlingh Onnes, superconductivity occurs when certain materials are cooled below critical temperature and it expels magnetic fields. In one example, a single grained itrium barium copper oxide compound is used as the superconductor. At room temperature, the superconductor does not have a magnetic force. When liquid nitrogen is poured over superconductor at 77 degrees kelvin, it boils and becomes gas because of heat received from super conductor. When it stops boiling, it is in thermal equilibrium with a temperature of 91 degrees Kelvin. This process is called zero field cooling meaning that no outside magnetic field influence was used. If a magnet is brought towards the superconductor, the superconductor is repelled and the Meissner effect takes place. As the material compound ejects the magnetic field from its interior, it transforms into its superconducting state. This state is explained by the Flux trapping effect which means that the superconductor is both repelling and attracting the magnet simultaneously causing magnetic levitation at a fixed distance.

Original sources:

http://chrisrieger.com/projects/levlight
http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_15-1-2007-15-54-23

 

levitating-light-bulb1 superconductivity-meissner

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