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RE:your observations

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In Reply to: RE: Here's a company that sells piezo-electric crystals... posted by Paul_A on April 05, 2011 at 18:43:15

I have no doubt whatsoever in what you hear. However data on piezo electricity is rather hard to come by in terms of a technical manual. It is usually confined to a footnote in some physics text.

The situation is even worse when investigating the electrical properties of crystals. Most books emphasize the the nature of the crystals , the coloration and other gemological properties, but not the electrical.

That being said the previously quoted text on electromagnetic waves by Johnk clearly states that it is presumed ( because not everything has been measured) that all materials are diamagnetic in nature, including a sheet of copper, germanium, etc. These are materials which are non magnetic at rest ( no electrical or magnetic field applied) but develop weak magnetism when the fields are applied.

This is based on the looser electron bonds in the outer shells of the material being temporarily dislodged and moved over by the applied field. Obviously, the fewer electrons in the outer shell ( using the Bohr's model) the more of this property is revealed. Obviously the movement of the electrons in the outer shell adds a vector to the magnetic field generated, however weak it is (10^-5 in the case of copper).

Stu

Stu

Follow Ups:

RE:your observations - pictureguy 18:54:01 04/08/11 (2)
I experimented (8th grade?) in making a shaded pole motor out of an ALUMINUM pie tin. It spun nicely in a 60hz AC magnetic field.

What is the difference between diamagnetic and paramagnetic?
Too much is never enough
- RE:your observations - Steve Eddy 08:24:59 04/09/11 (1)
  What is the difference between diamagnetic and paramagnetic?
  
  Basically, paramagnetic materials have a very very weak attraction to an applied magnetic field while diamagnetic materials have a very very weak repulsion to an applied magnetic field.
  
  Have you ever seen that superconductor demonstration where they show a magnet floating above a superconductor in a dish of liquid nitrogen?
  
  That's because superconductors are highly diamagnetic.
  
  se
  - RE:your observations - pictureguy 08:50:29 04/09/11 (0)
    I've done a SIMILAR demonstration using Aluminum.
    
    An Aluminum ring is placed around the core of a simple electromagnet. The Electromagnet is plugged into 60hz ac.
    The core, which is a separate piece and is longer than the coil by maybe 3" on each side is pulled to maximum extension on the high side and propped up using a wooden dowel rod. The core could be completely removed.....if you wished.
    Anyway, with the core displaced and with the ring in place, apply power and the Aluminum ring shoots into the air. OR if placed into the field while 'on', will simply float. Pushing the ring down deep into the field and resisting the force pushing UP will result in the ring getting HOT. And I mean too hot to touch. The electrical resistance of the Aluminum coupled with the induced current...and more of it as you force it deeper into the field.
    
    I did this in about '66 or maybe '67 at my 7th or 8th grade science fair. People didn't think aluminum was magnetic! Equally 'wowwing' of the crowd was the shaded pole motor...made from an aluminum pie tin.
    Too much is never enough

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