page_title: Magnetic levitation
section_title: Direct diamagnetic levitation
hierarchical_section_title: Magnetic levitation / Methods / Diamagnetic levitation / Direct diamagnetic levitation
caption_attribution_description: English: A live frog levitates inside the Ø32mm vertical bore of a Bitter solenoid in a magnetic field of about 16 tesla at the Nijmegen High Field Magnet Laboratory [1].
context_page_description: Magnetic levitation or magnetic suspension is a method by which an object is suspended with no support other than magnetic fields. Magnetic force is used to counteract the effects of the gravitational acceleration and any other accelerations.
  The two primary issues involved in magnetic levitation are lifting forces: providing an upward force sufficient to counteract gravity, and stability: ensuring that the system does not spontaneously slide or flip into a configuration where the lift is neutralized.
  Magnetic levitation is used for maglev trains, contactless melting, magnetic bearings and for product display purposes.
context_section_description: A substance that is diamagnetic repels a magnetic field. All materials have diamagnetic properties, but the effect is very weak, and is usually overcome by the object's paramagnetic or ferromagnetic properties, which act in the opposite manner.  Any material in which the diamagnetic component is stronger will be repelled by a magnet.
  Diamagnetic levitation can be used to levitate very light pieces of pyrolytic graphite or bismuth above a moderately strong permanent magnet.  As water is predominantly diamagnetic, this technique has been used to levitate water droplets and even live animals, such as a grasshopper, frog and a mouse. However, the magnetic fields required for this are very high, typically in the range of 16 teslas, and therefore create significant problems if ferromagnetic materials are nearby. Operation of this electromagnet used in the frog levitation experiment required 4 MW (4000000 watts) of power. 
  The minimum criterion for diamagnetic levitation is , where:
   is the magnetic susceptibility
   is the density of the material
   is the local gravitational acceleration (−9.8 m/s² on Earth)
   is the permeability of free space
   is the magnetic field
   is the rate of change of the magnetic field along the vertical axis.
  Assuming ideal conditions along the z-direction of solenoid magnet:
  Water levitates at 
  Graphite levitates at
caption: A live frog levitates inside a 32 mm diameter vertical bore of a Bitter solenoid in a magnetic field of about 16 teslas
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