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29 November 2024 03:51
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Welcome to the gyroscope forum. If you have a question about gyroscopes in general,
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Question |
| Asked by: |
Peter |
| Subject: |
Levitation |
| Question: |
Hi,
Whether an object will or will not levitate in a magnetic field B is defined by the balance between the magnetic force F = M B and gravity mg = V g where is the material density, V is the volume and g = 9.8m/s2. The magnetic moment M = ( / µ0)VB so that F = ( /µ0)BV B = ( /2µ0)V B2. Therefore, the vertical field gradient B2 required for levitation has to be larger than 2µ0 g/ . Molecular susceptibilities are typically 10-5 for diamagnetics and 10-3 for paramagnetic materials and, since is most often a few g/cm3, their magnetic levitation requires field gradients ~1000 and 10 T2/m, respectively. Taking l = 10cm as a typical size of high-field magnets and B2 ~ B2/l as an estimate, we find that fields of the order of 1 and 10T are sufficient to cause levitation of para- and diamagnetics. This result should not come as a surprise because, as we know, magnetic fields of less than 0.1T can levitate a superconductor ( = -1) and, from the formulas above, the magnetic force increases as B2.
How to defy the law of gravity by raising of a human body above ground without support and without material help yet the human is able balance off ground?
Peter Wee |
| Date: |
8 June 2006
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